NikonGear'23
Gear Talk => Camera Talk => Topic started by: Øivind Tøien on November 17, 2018, 13:43:35
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While I have been looking at the possibility of getting a D5300/D5500 for astrophotography use, a recent try with my D5100 at -16°C made me re-evaluate. The batteries only lasted 35 minutes from a warm and newly charged state before the cold brought voltage so low that it reached the cameras cutoff threshold. (Most of the battery capacity was recovered once rewarmed to room temperature.) Last night at -18°C (no wind) I managed closer to 3 hours /172 one minute frames with my D7100 from a pre-cooled state but with a fresh warm battery.
In normal shooting one can just keep swapping the batteries, but for astrophotography with tracking it is is preferable not to touch the rig too often. The apparent strength of the battery in the cold could apart from capacity issues also be related to different cutoff voltage thresholds by different bodies, so it is not given that for instance D500 will be better. (The initial reviews indicated that it utilizes a smaller portion of the battery capacity.)
Thus I am looking for test of the batteries of the following bodies at temperatures of about -20°C (close to 0°F): D5300, D5500, D7500 and D500.
A good test test protocol would be to first equilibrate the camera in a freezer for a couple of hours in a ziplock bag and connected to an intervalometer, then quickly swap in a fresh warm battery and do 5min dark exposures until the battery empty icon shows and no more frames are exposed. (5 min exposures should provide enough resolution and avoid wearing the shutter too much).
Are anyone in possession of any of these camera bodies willing to test this?
Black Friday is approaching quickly...
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While I realise this isn't an answer to the question you have raised, have you not considered an external PSU, or battery.
I had this issue with my D3 last year, this year I did a 2 months continuous time lapse, initially swapping batteries every couple of days, then I got an AC mains PSU, after that I only had to swap CF cards and reset the intervalometer because it stops after 999 exposures.
I have most of the bits I need to build a robust, warm, insulated power supply for the D3 to use in lowish temperatures, nothing as cold as you of course, but cold enough to cause significant problems with the batteries, say -5 to -9ºC.
I plan to use a plastic picnic box with foam insulation lining, a 12V golf trolly battery, a meter so I can monitor current draw and voltage, a thermometer so I can monitor internal and external temperature and a compartment to place a hot water bottle to keep things nice and warm. I bought a D3, AC Mains PSU and I am going to use the DC lead which has the appropriate plug to fit the D3 DC input socket. I will retain the AC Mains PSU and fit a paired non reversible plug and socket so it can still be used as intended.
I am also looking at racing batteries as an alternative to sealed lead acid batteries. Nominal 12V DC is suitable for the D3, I think the D7xxx bodies use nominal 7 to 8V DC.
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Thanks for the thought, Robert. When working at these low temperatures, I try to keep the setup as simple as possible. For instance no computers to control it, just an intervalometer etc. - limit external cabling to a minimum. There is also the consideration of traveling (air) or I am often on foot or with my bicycle.. Thus I am still looking for data on battery performance...
On further thought an external battery pack could be very useful for something like unattended overnight capture of meteor showers where an internal battery would not do. Like tonight's Leonid Meteor shower...
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I would think it may be easy, cheap and worthwhile to look into 'hand warmer' technology and then adapt/wrap that technology around the battery compartment.
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I would think it may be easy, cheap and worthwhile to look into 'hand warmer' technology and then adapt/wrap that technology around the battery compartment.
Thanks for the comment Gary. While that would be a rational idea in many applications, for astro imaging, one want to keep the sensor as cold as possible to minimize dark current noise (which is temperature dependent). I suspect it would be difficult to heat the battery compartment without affecting sensor temperature.
Besides my comment above, Robert's idea seems like a fun project.
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I got a response From Rudi Pohl to a post at the DPreview Astrophotography forum where I commented on the D5100 battery capacity in the cold:
"I have shot AP in -10 to -20 Celsius weather (not counting the wind chill), and have never had any kind of battery problems. I shoot with a D5500 and my two astro-buddies both use D5300s and we all use the standard Nikon EN-EL14a batteries with one for backup.
As I recall I get around 4 hours on a battery, very satisfied... just stay out of Live View."
I noticed that my D5100 batteries are EN-EL14, not EN-EL14a, the latter has higher capacity, but lower nominal voltage. I understand the cameras that used EN-EL14a had to receive a firmware upgrade to compensate for the lower voltage. Perhaps that has tweaked voltage threshold cutoff in a favorable direction with respect to cold? My D5100 has the firmware upgrade though but may be it does not work well with EN-EL14?
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Another response from another DPR forum member: "I can only get a couple of hours on a D5300 battery. The D7100 is indeed capable of more." No temperature was specified.
Perhaps Rudi's D5500 is somewhat better - at least battery CIPA numbers are higher for that body. Also Rudi now controls the camera from a computer which might help save battery.
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I have previously reported on this forum about my experience with the D500's battery life on longer exposures at elevated ISO's.
I am not sure if you read that or if other Nikons behave similarly, or whether this might have any bearing on your own recent experience.
I do have a D500 and would be willing to run a test for you, but I would need some guidance on how to set it up given that I live in south Africa, where we are currently experiencing a very hot summer with daytime temperatures running over 30 degrees C. Also, i do not have an external intervalometer, so the test will have to be done with 30-second exposures.
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Thanks Peter for reminding me of that thread, found it here:
http://nikongear.net/revival/index.php/topic,7150.15.html (http://nikongear.net/revival/index.php/topic,7150.15.html)
From that, unless there has been a firmware update improving the situation, it does not seem that D500 is a prime candidate for astrophotography use in the cold unless an external battery pack is used. With the limitation of doing 30 sec exposures, I hesitate to ask you to tax your shutter that much with meaningless exposures, however if you insist I would suggest the following (after all it sounds like one would not get that many shutter actuations).
The following assumes that you have a freezer with room for the D500 without any grip:
1. Set shutter speed to 30 seconds, ISO to 1600 (that is what I typically used for deep space imaging with a telephoto lens - going higher might blow out stars, depending on background illumination). If you have an AF lens attached, set AF to manual.
Set Exposure Delay Mode to 3 seconds.
2. Program the D500 to start exposures 2 hours ahead (to allow it to cool down), interval 36 seconds (to allow for writing to the card), number of exposures to 999x1 .
Do not turn on live view.
3. Put the D500 with lens and lens cap on in a ziplock bag and place in the freezer right away in a normal horizontal position so that it rests on the base. (simulating attachment to a tripod).
3b (Ideally you would swap battery shortly before 2 hours are up with a warm fully charged one before it starts exposing, but as the interval timer will then have to be restarted and condensation can form during the swap, you could skip this step and just test worse case scenario with a cold battery.)
4. Let it sit until it is no longer able to make exposures, for instance you could check back after 3 hours, considering your previous experience.
If you have a suitable freezer thermometer, record the temperature when removing the camera.
Let the camera warm up at room temperature in the ziplock bag.
5. Study the frames and count the numbers and time of first and last exposure.
6. (You might have go into the exposure delay menu again with a fresh battery and stop/reset it, as it sometimes want to go on even if the previous battery run out.)
Comment: I did notice in your previous thread that problems appeared at ISO 3200-6400, but I think it makes sense to use ISO 1600 for the test. We need to keep in mind that for astrophotography and particularly deep space imaging, it is not the ISO but the amount of light gathered that determines noise level. ISO adjustments are just used to ensure that the background signal is digitized at a high enough level to allow stretching, typically histogram 1/3 from the left.
By the way, how did you solve your problems on the occasion of the referred thread?
One last thought is that if the battery is charged at very high temperature, the charger might cut off before it reaches its nominal charge as voltage will be higher, so find a cool place with normal room temperature to charge batteries if possible.
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Hi, could this be a solution for you? https://www.tethertools.com/product/case-relay-coupler-bundle/
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A bit pricey and it is not really doing what one want - provide enough battery power. One would have to find a USB battery power source on top of that. Then one would have 3 devices just to supply battery power to the camera -lots of clutter. However there are just battery inserts/power cables for sale - Nikon has them both for the cameras that use EN-EL14a and EN-EL15 variants, for instance Nikon EP-5B, https://www.bhphotovideo.com/c/product/742056-REG/Nikon_27014_EP_5B_Power_Supply_Connector.html (https://www.bhphotovideo.com/c/product/742056-REG/Nikon_27014_EP_5B_Power_Supply_Connector.html) it is about $48 (search for Nikon power adapter). They are meant to be used with a Nikon supplied AC adapter, EH-5c. A comment under Q and A indicated that it is 9V power input: "I use mine with an elderly EH-5 AC power adapter (9V, 4500mA). "
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A bit pricey and it is not really doing what one want - provide enough battery power. One would have to find a USB battery power source on top of that. Then one would have 3 devices just to supply battery power to the camera -lots of clutter. However there are just battery inserts/power cables for sale - Nikon has them both for the cameras that use EN-EL14a and EN-EL15 variants, for instance Nikon EP-5B, https://www.bhphotovideo.com/c/product/742056-REG/Nikon_27014_EP_5B_Power_Supply_Connector.html (https://www.bhphotovideo.com/c/product/742056-REG/Nikon_27014_EP_5B_Power_Supply_Connector.html) it is about $48 (search for Nikon power adapter). They are meant to be used with a Nikon supplied AC adapter, EH-5c. A comment under Q and A indicated that it is 9V power input: "I use mine with an elderly EH-5 AC power adapter (9V, 4500mA).
Strangely, both EH-5b and EH-5c are discontinued, according to the website of Nikon Japan. EH-5c was launched this year. :o :o :o
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I will run the test over the weekend if that is OK?
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I have newer and older versions of the EH-5 power adapter (newest is labelled EH-5b) and all work perfectly with the several EP-5 variants I have around. I use them with D5300, D500, D8xx in studio settings. Just tried with my new Z7, all is well.
The EH-5 models deliver 9V, 4500mA according to the labels.
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I will run the test over the weekend if that is OK?
Thanks Peter, that would be fine.
Anyone with a D7500 who also want to take on the challenge?
Could use the same parameters with 30 sec exposures, or the 5 min exposures to save on the shutter.
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I have newer and older versions of the EH-5 power adapter (newest is labelled EH-5b) and all work perfectly with the several EP-5 variants I have around. I use them with D5300, D500, D8xx in studio settings. Just tried with my new Z7, all is well.
The EH-5 models deliver 9V, 4500mA according to the labels.
Thanks Birna for confirming the Voltage requirements.
What kind of connector is used between the power supply and the EP-5? If a proprietary connector, does it have more than two conductors?
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Four pins, if I recall correctly.
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Four pins, if I recall correctly.
Ouch, that complicates things, although the 4 connectors might still just be used to supply parallel power. Does it look anything like a standard connector? The square shape does not exactly look standard...
A quick search indicates that there are 9V capable power packs with 10Ah rating available for $50-60.
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No idea what constitutes a "standard" here as this is way outside my own fields of insight. All I know is that Nikon has used more or less similar camera-side plugs for their power supplies for the last twenty years or so.
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NG stalwart Jan Anne posted on the old Nikon web site (IIRC - I can't find it just yet) a thread detailing his battery charging arrangements for Nikon DSLRs that he was using whilst on remote canoeing trips where there was no mains electricity.
Once located, this thread has some interesting stuff in it that I think would be most useful to those building external battery packs for cold outdoors DSLR usage.
Does anyone have this link handy?
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Made an attempt, but could not find it. I vaguely recall the thread; I do not think he was set up to continuously power the cameras, just charge devices in the field, but I could be wrong. Besides it is a few years ago, so many new products could have appeared on the market with respect to battery packs.
I found that there are cheaper knockoffs of the Nikon adapter, they even includes the AC adapter at lower price (ca. $32 or less). comes in flavors for ENEL14 and EN-EL15:
https://www.amazon.com/Adapter-Coupler-Gonine-Replacement-Cameras/dp/B01D6B3830/ref=pd_lpo_vtph_421_bs_lp_tr_t_1?_encoding=UTF8&refRID=P53V2FAQBQ2Y2TWK2T40&th=1 (https://www.amazon.com/Adapter-Coupler-Gonine-Replacement-Cameras/dp/B01D6B3830/ref=pd_lpo_vtph_421_bs_lp_tr_t_1?_encoding=UTF8&refRID=P53V2FAQBQ2Y2TWK2T40&th=1)
https://www.amazon.com/Adapter-Coupler-Gonine-Replacement-Cameras/dp/B01D6BRKY8/ref=pd_lpo_vtph_421_bs_lp_tr_t_1?_encoding=UTF8&psc=1&refRID=P53V2FAQBQ2Y2TWK2T40 (https://www.amazon.com/Adapter-Coupler-Gonine-Replacement-Cameras/dp/B01D6BRKY8/ref=pd_lpo_vtph_421_bs_lp_tr_t_1?_encoding=UTF8&psc=1&refRID=P53V2FAQBQ2Y2TWK2T40)
Another one at $29 :
https://www.amazon.com/dp/B019RNU4II/ref=psdc_13535461_t2_B01D6BRKY8 (https://www.amazon.com/dp/B019RNU4II/ref=psdc_13535461_t2_B01D6BRKY8)
That one has a plug that resembles the Nikon version, but at that price one could afford to just cut the cable and solder on whatever connector is suitable.
A consideration is if there is a linear regulator to bring down power from 9 to 7.4/7.2 volts. If so that could possibly cause heating, which one want to avoid as dark current is temperature dependent. There are a couple of reviewers who bricked their cameras, one almost burned it, so I am not sure I would use it on an expensive unit like D500...
Also a rechargeable battery pack would be the major cost, for instance this one (the only one I found with 9V output on a standard power connector):
https://www.amazon.com/XTPower-MP-10000-External-Battery-10000mAh/dp/B00935L44E/ref=pd_rhf_se_p_img_6?_encoding=UTF8&psc=1&refRID=ZN6TGZ7BTA0NDFJ0DT9F (https://www.amazon.com/XTPower-MP-10000-External-Battery-10000mAh/dp/B00935L44E/ref=pd_rhf_se_p_img_6?_encoding=UTF8&psc=1&refRID=ZN6TGZ7BTA0NDFJ0DT9F)
It is only 36 Wh vs. 7.7 Wh for the an EN-EL14.
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Thanks Peter for reminding me of that thread, found it here:
http://nikongear.net/revival/index.php/topic,7150.15.html (http://nikongear.net/revival/index.php/topic,7150.15.html)
From that, unless there has been a firmware update improving the situation, it does not seem that D500 is a prime candidate for astrophotography use in the cold unless an external battery pack is used. With the limitation of doing 30 sec exposures, I hesitate to ask you to tax your shutter that much with meaningless exposures, however if you insist I would suggest the following (after all it sounds like one would not get that many shutter actuations).
The following assumes that you have a freezer with room for the D500 without any grip:
1. Set shutter speed to 30 seconds, ISO to 1600 (that is what I typically used for deep space imaging with a telephoto lens - going higher might blow out stars, depending on background illumination). If you have an AF lens attached, set AF to manual.
Set Exposure Delay Mode to 3 seconds.
2. Program the D500 to start exposures 2 hours ahead (to allow it to cool down), interval 36 seconds (to allow for writing to the card), number of exposures to 999x1 .
Do not turn on live view.
3. Put the D500 with lens and lens cap on in a ziplock bag and place in the freezer right away in a normal horizontal position so that it rests on the base. (simulating attachment to a tripod).
3b (Ideally you would swap battery shortly before 2 hours are up with a warm fully charged one before it starts exposing, but as the interval timer will then have to be restarted and condensation can form during the swap, you could skip this step and just test worse case scenario with a cold battery.)
4. Let it sit until it is no longer able to make exposures, for instance you could check back after 3 hours, considering your previous experience.
If you have a suitable freezer thermometer, record the temperature when removing the camera.
Let the camera warm up at room temperature in the ziplock bag.
5. Study the frames and count the numbers and time of first and last exposure.
6. (You might have go into the exposure delay menu again with a fresh battery and stop/reset it, as it sometimes want to go on even if the previous battery run out.)
Comment: I did notice in your previous thread that problems appeared at ISO 3200-6400, but I think it makes sense to use ISO 1600 for the test. We need to keep in mind that for astrophotography and particularly deep space imaging, it is not the ISO but the amount of light gathered that determines noise level. ISO adjustments are just used to ensure that the background signal is digitized at a high enough level to allow stretching, typically histogram 1/3 from the left.
By the way, how did you solve your problems on the occasion of the referred thread?
One last thought is that if the battery is charged at very high temperature, the charger might cut off before it reaches its nominal charge as voltage will be higher, so find a cool place with normal room temperature to charge batteries if possible.
Ok, result for D500: 274 30-second exposures at ISO1600. This was with an un-chipped 55mm f2.8 AI-S lens attached, so no power use for the lens whatsoever. This was without changing the battery, and the temperature was -16 degrees C. I did open the fridge at the beginning of the test, so the camera was not quite that cold at the beginning, possibly -12?
I must say, this is more than I expected.
With regard to how I overcame the bettery life issue at high-ISO, I shoot most of my astro shots at ISO 400. I can see no negative impact on image quality between shooting at elevated ISO or shooting at 400 and lifting exposure to the same level, and usually I don't, instead I will lift exposure in selected areas, thus the overall image quality may even be slightly better.
The disadvantage is that it is impossible to judge the composition, so the session will always start with a few high-ISO shots.
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Ok, result for D500: 274 30-second exposures at ISO1600. This was with an un-chipped 55mm f2.8 AI-S lens attached, so no power use for the lens whatsoever. This was without changing the battery, and the temperature was -16 degrees C. I did open the fridge at the beginning of the test, so the camera was not quite that cold at the beginning, possibly -12?
I must say, this is more than I expected.
With regard to how I overcame the bettery life issue at high-ISO, I shoot most of my astro shots at ISO 400. I can see no negative impact on image quality between shooting at elevated ISO or shooting at 400 and lifting exposure to the same level, and usually I don't, instead I will lift exposure in selected areas, thus the overall image quality may even be slightly better.
The disadvantage is that it is impossible to judge the composition, so the session will always start with a few high-ISO shots.
Thanks so much Peter for carrying out this test. This was somewhat encouraging and gave me something to think about. I might want to repeat this test now with my D7100 to see how it responds in comparison. I have done astro imaging with 30sec exposures (I am usually at one minute) , but I cannot recall how long it lasted on that occasion.
I actually handled both D500 and D7500 bodies without lens, but with my own battery inserted for correct weight in the local store here in Fairbanks yesterday. (They do not use to stock high end models so this was a bit of surprise). Both very nice bodies in their own way, the D500 not as bulky and heavy as I recall from a previous occasion, and has the edge when handling with thick mittens. Both could be handled well with a pair of fleece gloves. When I asked them about the battery in these cold environments, they indicated that battery in the D7500 lasted longer than D500 (not surprising). For astro use, the flip out screen of the D7500 has a little edge over D500 in that it can be pulled out a bit further from the body, as the hinge is attached closer to the bottom (but could also be more fragile). My right angle finder might obstruct the view of both of them though.
Using lower ISO and stretching certainly should be better to avoid blowing out stars and get better star colors, as long as there is no pattern noise lurking at the bottom messing up things like on my D7100 (which is OK at ISO 1600).
One thing that favors D500 is a better Hot Pixel Supression (HPS) algorithm. According to recent analysis,
https://www.dpreview.com/forums/post/61908926 (https://www.dpreview.com/forums/post/61908926) , D500 uses a 24 nearest neighbors algorithm, and while the principle is similar for D7500 (which is somewhat better than D5300) it is based on nearest 8 or 12 same color neighbors, https://www.cloudynights.com/topic/635441-aa-filter-spatial-filter-and-star-colours/page-3. (https://www.cloudynights.com/topic/635441-aa-filter-spatial-filter-and-star-colours/page-3.). Thus D500 will not suffer from the "star eater" syndrome, while D7500 might be slightly affected in that colors of the smallest stars might be off if a high resolution lens is used, typically turning them green. That said, D5300, which is even worse, is the most popular Nikon model for astrophotography.
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I tested the battery with D7100 in freezer as I outlined above at ISO 1600. No battery change, thus both camera and battery was conditioned before test starts (as I was short of time and camera already had been outside, conditioning time was 1 1/2 hour.) The test is not as stringent as I hoped as a thermocouple recorded wide temperature fluctuations, mostly between -12°C and -21°C (likely due to cycling of the freezer. Retrospectively I should have taped the thermocouple to the camera instead of hanging free outside the plastic bag).
Result: 378 30-second frames, total time including exposure delay and time to write to card = 3.78 hours. In other words the Li-20 battery of the D7100 lasted about 38% longer than the one in the D500 test. After rewarming at room temperature the battery still showed empty when inserted back into the camera. It recharged back to full capacity and status shows 0 battery age.
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Øivind, its taken me a while to find them on the old site, but these are Jan Anne's links that I was thinking of:
https://www.fotozones.com/live/index.php?/forums/topic/49463-d800e-running-on-a-60wh-batterypack/&tab=comments#comment-397368
The external pack shown could be kept warm without heating the sensor in the camera.
(EDIT: The links refer to Ebay listings, which are now outdated, but thankfully newer alternatives are shown by Ebay.)
and
https://www.fotozones.com/live/index.php?/forums/topic/49171-nikon-powered-iphone-5/
Made an attempt, but could not find it. I vaguely recall the thread; I do not think he was set up to continuously power the cameras, just charge devices in the field, but I could be wrong. Besides it is a few years ago, so many new products could have appeared on the market with respect to battery packs.
.............................................
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It seems you need an account on Fotozones in order to access this information.
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FWIW, here's one that I have, somewhere.
https://www.amazon.com/gp/product/B019RHJRM8/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1
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It seems you need an account on Fotozones in order to access this information.
Maybe. The first link opened for me, no problem. Safari could not load the second link, but it did open in Cnrome. I had an account, back when it was the old site, but can no longer log in, for some reason. You might try different browsers, or maybe you've been blocked.
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The latter option wouldn't surprise me ...
Tried both links, same result.
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The latter option wouldn't surprise me ...
Tried both links, same result.
It wouldn't surprise me either. which is why I mentioned it. It's much nicer here anyway.
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Both links work OK for me, agreed, much nicer here, by far. 8)
I did notice a post in the thread from NFOTO, a life member with quite a few posts, some may remember him... ;D
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Both links work OK for me, agreed, much nicer here, by far. 8)
I did notice a post in the thread from NFOTO, a life member with quite a few posts, some may remember him... ;D
Ayuh, I too was a life member, which probably means I'm dead and don't know it. ;)
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Dallas recently had a cull, which I narrowly avoided. Else I would have been dead too. But then maybe I am? Is this the afterlife??? ;D Whoops, OT.
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Thanks folks for the access feedback. Yes, Seapy is right - Dallas did have a cull earlier this year of old unused logins which I had forgotten about. I login occasionally, which is probably why I am OK.
I will PM Øivind and see if he can open the two links to Jan Anne's original threads.
The first link shows how Jan Anne used a high capacity lithium battery which was connected by a cable to a "fake" EN-EL15 battery adapter for his D800E. This means that the real battery is outside of the camera body and can be kept warm, without adding any heat to the camera body and in particular to the sensor. The gist of it all is in the Ebay links that portray the componentry - modern day Ebay alternatives to these are still alive:
EN-EL15 adapter: http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=111037377156&ssPageName=ADME:L:OU:NL:3160
Voltaic V60 Batterypack: http://www.voltaicsystems.com/16wattkit.php
Voltaic MacBook adapter (scroll to Optional Computer Adapters): http://www.voltaicsystems.com/adapters.shtml#laptop
********************************
The second link shows how he could use one of his EN-EL15 camera batteries to power his smart phone.
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Thanks Hugh. I have kept my Fotozone login to be able to access my old posts there, so I could access both of the links. Still looking though the information, right now drowning in open tabs from links in the posts. ;D
Birna, I have emailed you some .pdf archives.
I tested opening the links in an incognito window in Chrome and I had access even there.
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Thanks, Øivind.
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After looking through links I found that selections are limited for battery devices with 9V output that most of the battery adapters require.
One of these is a series of devices referred to by Jan Anne, QIDIAN 1A/1.5A/2A/4A 6*18650 Mobile Power Bank Battery Charger Kit. The nice thing is that it is user replaceable 18650 batteries. I only found one that currently was in stock, the model almost at the bottom with 2600 mAh Sanyo batteries at $47.23. All other models out of stock or discontinued. This would give 57.7 Wh capacity, but the device is fairly big, 183x92x24.8mm, Weight 163g presumably without batteries. So it might not be ideal for travel.
https://www.fasttech.com/products/1424/10004461/1341206 (https://www.fasttech.com/products/1424/10004461/1341206)
One could perhaps wait for a smaller model to be available, the 4 cell version with 3.4 Ah Panasonic batteries at $44.11 without power brick is out of stock and would likely be more ideal at 50.3 Wh capacity and 119.5 x 83.1 x 23.7 mm and 102 g for the case only.
https://www.fasttech.com/products/1424/10004461/1341407 (https://www.fasttech.com/products/1424/10004461/1341407)
The other device is one I referred to earlier with 37Wh capacity at $59.90. There are a couple of positive user reviews from someone who used it with Canon bodies for astro imaging. It is considerabley smaller, 125mm X 76mm X 23mm, 290g. https://www.amazon.com/XTPower-MP-10000-External-Battery-10000mAh/dp/B00935L44E (https://www.amazon.com/XTPower-MP-10000-External-Battery-10000mAh/dp/B00935L44E)
There are in addition a somewhat wider selection of devices that output 12-24V, especially among the solar power related ones, including the products from the Voltaic company Jan Anne referred to. However these tend to be expensive (for instance this one, https://www.amazon.com/gp/product/B00ISH4WEW?th=1 (https://www.amazon.com/gp/product/B00ISH4WEW?th=1) ) and would require a DC to DC converter cable, adding some clutter/complexity - I found this one at $12: https://www.amazon.com/12V-24V-Step-Down-EN-EL14-EN-EL15-EN-EL21/dp/B07GQK52YP (https://www.amazon.com/12V-24V-Step-Down-EN-EL14-EN-EL15-EN-EL21/dp/B07GQK52YP)
Another, perhaps better alternative than the last one, provided that a Nikon body does not draw more than 1A of current is a USB 5V to 9V converter (I found a reference to a Canon T3i where live view was drawing 0.5A : https://www.cloudynights.com/topic/540385-dslr-power-requirements/ (https://www.cloudynights.com/topic/540385-dslr-power-requirements/) ) Efficiency of the converters below are listed as 95%. This would greatly widen the choice of battery banks. However it would require the battery bank to be able provide at least 2A, possibly more to be on the safe side. I found two products, both about $8, they are basically just cable with a small lump for the converter, not much clutter as a cable will be needed anyway:
https://www.amazon.com/HeavenLights-DC-Converter-Step-Voltage/dp/B0796R99MN (https://www.amazon.com/HeavenLights-DC-Converter-Step-Voltage/dp/B0796R99MN)
https://www.amazon.com/KUNCAN-Converter-Step-Voltage-2-1mm/dp/B01ID90E3C (https://www.amazon.com/KUNCAN-Converter-Step-Voltage-2-1mm/dp/B01ID90E3C) (The 5.5mm plug looks a little short on this one.)
With the plethora of 5V battery banks available at various form factors and at lower prices, one could even afford to try out minimal solutions, and scale up if capacity needs appear to be higher, as long as the 2A current rating is present (which seems to be common).
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I spent a lot of time selecting a 5V USB battery bank, just to find that when I had made my selection of a popular 16 Ah bank, neither Amazon nor B&H would ship to Alaska, regardless of the capacity of the bank (Even UPS ground has to go by air here). Ended up ordering a charging case for four 18650 batteries (without batteries), equivalent to the Qidian case Jan Anne used and some of the items above + a little more, allowing multiple strategies. Now I likely have to go and see if I can find the 18650 batteries on the local market...
Considering the difficulty of shipping lithium batteries these days to the US, I would not consider any of the Qidian cases with batteries in the links above. If interest, I can provide details of what specific items I ordered once items have arrived and checked if they work. Hopefully I can get it all operative before the Geminid meteor shower Dec. 14.
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Geminid meteor shower Dec. 14.
Will this be another opportunity for me to capture another Iridium Flare... LOL ;D ;D ;D
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If you are handy with a soldering iron you could put 2 5V packs in series and then a 9V voltage regulator in-line. That would reduce the current draw on the batteries.
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If you are handy with a soldering iron you could put 2 5V packs in series and then a 9V voltage regulator in-line. That would reduce the current draw on the batteries.
While I no problems with soldering together stuff or even designing and building circuitry using electronic CAD (it usually gets more expensive than buying ready made stuff), serially connecting Li-Ion batteries without special controlling circuitry can be a risky affair - issues with balancing the discharge of the cells (although it might not lead to a disaster if adequate protection circuitry is present in the battery banks). It would be better to buy a bank with more batteries. Using DC- to DC converters is a safer way to provide the proper voltage.
However I suspect the Tomo battery bank/charger that that has arrived to be adequate based on some preliminary current measurements. The bank takes 4 18650 cells - I got in the Panasonic 3.4 Ah cells from an ebay supplier yesterday (13.6 Ah total), and just charged them overnight+. I am currently testing their capacity with a USB LED lamp that only draws a pretty constant 270 mA, so I will know after 33 hours or so if the cells keep their nominal capacity or is a counterfeit with much less capacity... (A thermocouple logger that I previously designed records temperature of the lamp at 1 min intervals so that I know when it will cut out - a good sign so far is that it initially took more than 12h to charge the banks with a 1A power supply.) That would give me about 49 Wh of energy at room temperature, or with losses in the internal DC converter of the bank + the external 5V-9V DC converter (likely 2 x 5 % loss) about 46.5 Wh to the camera.
At my current location I also have the option of running extension cables for an overnight event - I have bought parts to allow running both my D7100 and my D5100 at the same time with AC power. Weather forecast is not good though, so I might miss the whole Geminid meteor shower...
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The mornings of 13th and 14th December are forecast cloudy with rain or snow at my various vantage points in Northern England and Scotland. >:(
Agree re. adapting or coupling power banks, better to use correct, designed for the job power sources.
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A little update on the progress here. Below is a list of the item I bought. They were intended to be able to power one body from the battery bank and as a plan B two bodies (D7100 and D5100) from AC power. In addition comes the 4 Panasonic 3.4 Ah 18650 cells that an ebay supplier was able to ship. They tested OK with respect to capacity so are likely not counterfeits :
(https://otoien.zenfolio.com/img/s/v-3/p3235905937.jpg)
The Tomo battery bank (13.6 Ah) that also can act as an 18650 battery charger was able to power each of D7100 and D5100 even in live view. The bank has a 2A output limit, but one can go somewhat above that before the short circuit protection kicks in and it shuts down. The current display fluctuates a bit and showed a little higher values than a dedicated USB power meter. The current draw is not unsurprisingly higher on the D7100 than the D5100. For asto images I would not use live view except during aiming and focusing. Keep in mind that the actual current will be something near half of this after conversion to 9V with better than 95% efficiency.
(https://otoien.zenfolio.com/img/s/v-3/p3235905938.jpg)
(https://otoien.zenfolio.com/img/s/v-3/p3235905940.jpg)
The first test test with the D5100 indicated no problems with powering it with 5 min exposures for >20 hours. But wait - when I downloaded the card there were 45 folders with image files on the card. What was going on? This is a characteristic of the D5100. If power is interrupted (for instance battery swap without turning power off first), it will forget all changes to the settings, including the number of the last image captured. So when power goes on again the image number will be a duplicate of an existing one, so a new folder is created. So not so good.
Further outside testing with the D7100 although not subject to the same problems with not saving settings changes, revealed similar problems, with shutter getting hung up now and then and not completing the cycle. Only on next release will the shutter recover and then funtion normally on the release after that. Here is a capture that revealed the problem: During shutter actuation or termination, the power peaks, here at 2.5 A well above the 2A rating. In this particular case, there was not a power cut, but obviously it is near the limit:
(https://otoien.zenfolio.com/img/s/v-3/p3235905939.jpg)
(Captured though a window, it was -13°C outside).
Last night I set up to directly measure the current draw of the two bodies by passing the 9V power supply though a 0.1 Ohm resistor and recording voltage drop with my DIY oscilloscope. The red line is the same with a 3300uF capacitor across the power leads to smooth the peaks. Exposure time 0.5 seconds. First peaks is when mirror goes up, second when mirror goes down.
D7100:
(https://otoien.zenfolio.com/img/s/v-3/p3235881792.jpg)
Idle current is about 0.3A, the mirror up peaks near 2A, then while shutter is open about 0.37A, new 2A peak when mirror is returned, and then fluctuating around 0.48A while image is written to SD card. Most important the high current draw during the mirror movement lasts 45-50 ms each. The capacitor helped to dampen the peaks but was not enough to keep current below the 1A output spec. of the DC-DC converter.
D5100:
(https://otoien.zenfolio.com/img/s/v-3/p3235881791.jpg)
A similar pattern with 2A peaks during mirror movements. However the high current periods last longer, about 95 ms and each consists of two peaks, which is even more problematic. The idle current draw is lower though, about 0.14A and when shutter is open about 0.37A.
Here is a detail of what happens when the power draw gets too high and there is consequently a power cut to the D7100:
(https://otoien.zenfolio.com/img/s/v-3/p3235881793.jpg)
The night of the Geminid meteor shower it magically cleared up after snowing before midnight. After my first experiences I had already decided to go for plan B, powering both cameras with AC power from a long extension cord which was available at the location. The two cameras were going though the night and collected 60GB of image data. However the D5100 which was released with the internal timer tended to stop recording after less than 250 frames and had to be restarted in spite of the max number of frames set to 999. This did not appear to be a power problem though as there was no accumulation of image folders.
For powering the cameras from the battery bank I am looking into adding a 1 F 9V super capacitor across the power leads. I will just have to figure out how to dampen the inrush current on first power up. So it looks like I will get use for my soldering skills after all.
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Very interesting Ølvind, will have to read again and again for it all to sink in but very interesting procedures and recording. Thank you for posting such detail.
It seems I may have to modify my proposed creation because I don't think I will be using the D3 for star photography into the future, rather a D800 or D810 which is on the horizon. The battery voltage differs between the D3 and the D8XX. Your experiences will more directly relate to my project now, I think! ::)
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For powering the cameras from the battery bank I am looking into adding a 1 F 9V super capacitor across the power leads. I will just have to figure out how to dampen the inrush current on first power up. So it looks like I will get use for my soldering skills after all.
I'm monitoring your posts with much interest, Øivind!
That said, I would concern about the 1F super capacitor: wouldn't the initial current pouriing into the empty cap damage the battery?
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I'm monitoring your posts with much interest, Øivind!
That said, I would concern about the super capacitor: wouldn't the initial current pouriing into the empty cap damage the battery?
Yes, you identified the problem Akira - that is what I meant with "I will just have to figure out how to dampen the inrush current on first power up." A solution is to charge the super capacitor though a current limiting resistor and then discharge it though a diode connected in parallel with the resistor. However the charge rate will then be relatively low when the capacitor is recovering from the current draw between mirror movements. I might just order the super capacitor, power resistor and diodes to see if it works. Other solutions will requite more circuitry and require me to design a print, so a slower process.
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Yes, you identified the problem Akira - that is what I meant with "I will just have to figure out how to dampen the inrush current on first power up." A solution is to charge the super capacitor though a current limiting resistor and then discharge it though a diode connected in parallel with the resistor. However the charge rate will then be relatively low when the capacitor is recovering from the current draw between mirror movements. I might just order the super capacitor, power resistor and diodes to see if it works. Other solutions will requite more circuitry and require me to design a print, so a slower process.
Oh, yes, I failed to find the English term "inrush current". Sorry for my redundant post.
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No problem Akira, good to have it explained several ways. :)
I have now posted some results from the Geminid meteor shower here:
http://nikongear.net/revival/index.php/topic,8225.msg133663.html#msg133663 (http://nikongear.net/revival/index.php/topic,8225.msg133663.html#msg133663)
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The super capacitor arrived and so far it seems to be a success in capping the current draw with a peak only slightly beyond 1A. As there is a conversion from 5V to only 9V with >95% efficiency this should be OK. The 1F super capacitor (SCMR22L105SRBB0) is rated to 9V which is a bit marginal, so if it is to be used in very hot environments perhaps a capacitor with higher voltage rating should be selected. The attached graph shows current draw with D7100 at the end of an exposure, followed by the beginning of another exposure (I believe I used continuous shooting mode on this one).
The bench test indicated no problems powering any of the bodies from the battery banks as long as the exposures are not to frequent. As this is written it has been sitting outside for about 8h at -25°C powering the D7100 to record the Quadrantid Meteor Shower. We will see if there are any problems once I stop acquiring images and get them downloaded. The connections are shown below.
A limitation of this construction is that recharging the capacitor is relatively slow, so for instance 1/2 second exposures in continuous mode eventually failed, while 10sec exposures in continuous mode or 1/2 sec exposures with 10 sec pause between seemed OK.
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No images show, Øivind ...
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No images show, Øivind ...
They show both in an incognito window in Chrome and an old IE version here, none of them should have special permission to my zenfolio account (and IE would not share cache with Chrome). Perhaps a temporary problem with connections?
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Using Firefox 64 bit here and no images show. However, if I copy the URL inside your IMG tags into another browser tab, the pictures show? strange. Perhaps your image hosting company doesn't like hot linking?
You can attach the images directly to your post instead.
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Using Firefox 64 bit here and no images show. However, if I copy the URL inside your IMG tags into another browser tab, the pictures show? strange. Perhaps your image hosting company doesn't like hot linking?
You can attach the images directly to your post instead.
Are you talking about the schematics in the reply #48?
My 64bit Firefox can display them with no problem.
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I have edited the post now and attached the two images. Except for one or two specific very strange hiccups in the past on a DPreview post I have never had problems with hotlinking from Zenfolio.
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I just rigged down and downloaded the images. The D7100 lasted for 8 hours and 37 minutes (846 exposures, each 30s) at -25°C before image data collection stopped due low power.
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That is a nice achievement, in terms of power supply to any digital camera.
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I just rigged down and downloaded the images. The D7100 lasted for 8 hours and 37 minutes (846 exposures, each 30s) at -25°C before image data collection stopped due low power.
Nice! Do you activate the dark frame subtraction (long exposure noise reduction)? Or, is it not necessary for 30 sec. exposure in such a cold environment?
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I agree. This is good work - I have no doubt that there will be others here that will benefit from what you have achieved.
That is a nice achievement, in terms of power supply to any digital camera.
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Yes indeed, I for one am watching and learning.
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Thanks for the enthusiastic comments all of you. Retrospectively it would have been easier and simpler, if slightly more expensive to choose the battery bank that is capable of outputting 2A at 9V, linked to earlier in this thread if it had been possible to have it shipped to me. However this was a possible solution and much more fun figuring out. Besides I like the fact that the bank also doubles as a charger for my Convoy S2+ UV nichia 365 nm LED light that I recently acquired and is currently running on on old salvaged laptop cells. The Panasonic cells I use for the bank itself are supposed to be the same running in Tesla S models, so it not surprising they perform well. After warm up to room temperature the unloaded voltage of each cell was 3.63V so it will likely last quite a bit longer at room temperature.
Akira, I turn long exposure noise reduction off when doing tracked night sky imaging for stacking, so there is no overhead while acquiring the image data. I do a separate series of dark exposures at the same ISO and exposure time (I am actually acquiring those data while writing this). As long as temperature is the same (still -25°C here) and no light is allowed to enter the sensor, it does not matter to wait until the next day. In addition I do a number of bias exposures at very high shutter speed at the same ISO.
The super capacitor was for this test just connected up on a screw terminal protected in an antistatic ziplog bag. Now on to find the best way to place and solder components on at perf board and get it all potted (hot glue is usually my friend for this, but I need to check if it will be too warm for the super capacitor first).
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Another update: During the above test and tracking attempt a few nights later where temperature dropped to -30°C, while the battery bank and camera worked without a hitch, my SkyTracker stopped working abruptly. First night this happened about half way, and the remote release cable appeared to be snagged between the rotating platform and the tracker, but the next colder night it only lasted for about 40 minutes before it stopped. I recalled some previous problems when it got that cold.
I then got the idea to also power the tracker from the same 9V outlet via the super-capacitor, and a quick test revealed that power consumption of the tracker is very low, only 70mA drawn from the battery bank. Last night the cold weather at -34°C appeared to open up enough with stars visible for a tracking test test closer to midnight. Of course right after everything was set up and aligned clouds started drifting in and with that it warmed up towards -30°C during the test. Clouds were still transparent enough to see some stars to check if tracking worked. Except that the camera hit the polar scope at some point (ouch, luckily I caught it after only two non-tracked frames so no damage done), the SkyTracker and the D7100 worked OK though the 4hour test. So as long as the tracker has power it might still work at these low temperatures. I will now incorporate the extra power outlet for the tracker in the final design. It is anyway very awkward to change the AA batteries on the tracker (needs pliers/leatherman tool to get the battery holder out), so using the 9-12V power inlet might be a good solution in spite of the extra cable clutter.
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Very interesting Øivind, I am following this with great interest.
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In a further modification to the super-capacitor circuit I included an extra schottky diode at the input to prevent charge in the super capacitor to go back to the source. This also brings the voltage very slightly down, which is safer with the 9V rating of the super capacitor:
(https://otoien.zenfolio.com/img/s/v-3/p3288592153.jpg)
To avoid extra cable clutter I got the idea to build the super capacitor circuit into the SkyTracker. At first sight of the internals, the space looks tight, showing the large worm drive to the right, the DC motor with its clock drive and an optical encoder that provides feedback on speed to the upper left, and the control board to the lower left.
(https://otoien.zenfolio.com/img/s/v-3/p3288592094.jpg)
But underneath the control board I found some unused space (image rotated 90° clockwise compared to last one).
(https://otoien.zenfolio.com/img/s/v-3/p3288592095.jpg)
My hard-wired circuit board looks a little odd, as the components had to clear the transistors etc. underneath the control board.
(https://otoien.zenfolio.com/img/s/v-3/p3288592097-5.jpg) (https://otoien.zenfolio.com/img/s/v-3/p3288592098-5.jpg)
It was finally insulated on the bottom and simply hot-glued glued in place, so it looks a little ugly. I can still have batteries installed in the tracker as a backup solution for the tracker.
(https://otoien.zenfolio.com/img/s/v-3/p3288592096-5.jpg)
A difficult part of the modification was drilling the hole for the power outlet to the camera in the tracker at the right location. Generous amount of plastic bags and masking tape was used to prevent metal filings getting to the sensitive clockwork mechanism.
(https://otoien.zenfolio.com/img/s/v-3/p3288592134-4.jpg)
I also changed the cable to the DC converter with a flexible silicone insulated one I had in stock, as the original one cracked after only a couple of uses. A similar cable runs to the connector for the fake EN-EL15 battery (hotglue is your friend). The DC converter fits on the side of the Tomo battery bank contained in a modified ThinTank pouch that I got as a freebie at some point.
(https://otoien.zenfolio.com/img/s/v-3/p3288592131.jpg)
The complete setup (except intervalometer not connected to the camera yet). The ThinkTank pouch with the battery bank is conveniently attached with its Velcro attachment to the tripod leg.
(https://otoien.zenfolio.com/img/s/v-3/p3303839029.jpg)
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Very nice DIY job!
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This is neat, Øivind!
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Oivind, I showed your handiwork to my friend that does astrophotography, because I knew that it would interest him. His comment below:
"I’d like to see some results…
My experience is that unguided trackers have way too much wobble, unless you spend the $$$ to get precision ground worm and ring gears."
Examples of images using the modified rig, along with your comments, would be very nice. :)
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Thaks for the enthusiastic comments, Erik and Akira.
Carl, If fixed the wobble in the Skytracker already at the start by removing a washer in the rotating base. Both Armando and me have shown plenty of results with 300mm focal length on the SkyTracker Classic (ver. 2) in the Night Sky shots thread, most of mine based on stacking 60 second exposures, for instance this page, :
http://nikongear.net/revival/index.php/topic,1992.msg130037.html#msg130037 (http://nikongear.net/revival/index.php/topic,1992.msg130037.html#msg130037)
The last image of the North America Nebula is at 2500 pixels horizontal resolution if you open it in a new tab.
Here is an image recorded using the battery bank to power the D5100 with 300mm and the tracker with super-capacitor at -40°C, also at 2500 pixels horizontal resolution if you open it in a new tab. The super capacitor circuit was still on the prototype stage, so not built into the tracker yet, just contained in a Ziploc bag. The battery bank lasted for 2.5 to 3 hours before the Li-Ion batteries got too cold and the battery bank shut down. It was taken inside to warm up for 15-30 minutes and then lasted until the end for another 2.5 hours, including recording about 90 darks at the end when the target got out of range. Light pollution was a little too strong to get a good view of the Jellyfish nebula to the center left, but I like how the Shoe Buckle Cluster at the right edge came out.
(https://otoien.zenfolio.com/img/s/v-3/p3306795092.jpg)
Nikon D5100 with 300mm f/4 PF @ f/4.5 front aperture, ca. 66 minute total integration time at ISO 400. Jellyfish Nebula (IC 443) left, and Shoe Buckle Cluster (M35) right edge.
A lot of advanced trackers that allow guided exposures stop working at much higher temperature. The mounts owned by our university's Physics department did not even work at -10°C during a recent star party.
I was tracking last night with the D500, but have not gotten to process them yet. Lately I only need to throw away about 10% of the frames due to mis-tracking with careful polar alignment, depending a little how far away from the pole I image. The periodic error curve has a flat portion and then a bump when it reaches the end of the worm drive at 9-10 min intervals where a frame or two sometimes need to be discarded. Lots of those using guided tracking track for much longer times, sometimes 5-10 min with similar magnification or even more, but due to light pollution I would blow out the stars with that long exposure.
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Thaks for the enthusiastic comments, Erik and Akira.
Carl, If fixed the wobble in the Skytracker already at the start by removing a washer in the rotating base. Both Armando and me have shown plenty of results with 300mm focal length on the SkyTracker Classic (ver. 2) in the Night Sky shots thread, most of mine based on stacking 60 second exposures, for instance this page, :
http://nikongear.net/revival/index.php/topic,1992.msg130037.html#msg130037 (http://nikongear.net/revival/index.php/topic,1992.msg130037.html#msg130037)
I was tracking last night with the D500, but have not gotten to process them yet. Lately I only need to throw away about 10% of the frames due to mis-tracking with careful polar alignment, depending a little how far away from the pole I image. The periodic error curve has a flat portion and then a bump when it reaches the end of the worm drive at 9-10 min intervals where a frame or two sometimes need to be discarded. Lots of those using guided tracking track for much longer times, sometimes 5-10 min with similar magnification or even more, but due to light pollution I would blow out the stars with that long exposure.
Thanks, Oivind, I will pass that on to my friend. :)
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Carl, I edited in parallel, please see the last part of my post. :)
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Carl, I edited in parallel, please see the last part of my post. :)
No problem, Oivind. More to come....... :)
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An analysis of the D500 power consumption:
The peak current draw of the D500 is even higher than the D7100, exceeding 3A. However the final version of the super capacitor circuit nicely caps the current draw from the DC-DC converter at ca. 1A. This curve is with the Nikon 12-24mm mounted, so a worst case scenario (see below) rather than minimum current draw without lens:
(https://otoien.zenfolio.com/img/s/v-3/p3288592157.jpg)
Blue line current draw by D500, red line current draw from DC-DC converter, teal line voltage supply to D500.
The 8.5 V supply in idle mode of the D500 registers at 98-100% battery power. The voltage dip is partly due to that I am passing the supply though the 0.1 Ohm resistor I use to measure the current draw, and does not affect the battery state display. Another reason is voltage drop over the diodes, about 0.25V per diode and increasing somewhat with the current draw. This voltage drop is partly by design, as it will help draw current from the super capacitor rather than the power bank.
Here is a chart comparing static types of current draw by D5100, D7100 and D500. Each state was measured over several seconds with a highly accurate voltage meter.
(https://otoien.zenfolio.com/img/s/v-3/p3310729627.jpg)
While the D5100 generally use draws little more than 2/3 of that of D7100, what is striking is the minimal % increase in current draw of D500 over D7100, generally in the 2-8% range. The exceptions are Live view exposure where the screen back light stays on with D500 opposed to D7100. The latter draws about the same current during live view exposure as one in viewfinder mode. Also video recording use a little more on D500, however I had digital image stabilization turned on in D500. Image review with paging though frames as fast as possible also is higher, which could be due to D500 being able to page though images faster, perhaps in combination with higher display resolution.
Using high ISO has no effect on current draw during a 30 second exposure. I also tried longer exposures and turned High ISO noise reduction on and off, but there was no difference. so Peter, your shorter battery life at long exposures and high ISO mentioned on page 1 seems to have other causes.
If AFS lenses are attached, current draw even when idle might increase 30-40%, however active VR is only a 10% increase in the 300PF, about the same as continuous AF operation. The 12-24mm has higher idle current draw but uses little extra during continuous AF operation. My custom chipped 55mm f/3.5 micro did not draw any measurable power compared to my second non-chipped copy. (It likely just powers up to communicate when mounted).
There is a tiny bit of identical current draw in standby mode and with the power switch off. It is a respectable 167 uA (mikro Ampere) in D500, considering that both the top display and the viewfinder mask both receive power. In the D5100 the standby/off state draws almost 1mA, which could drain the battery in 47 days.
If we integrate the curve of the shutter actuation (one with the 55 micro used as base) it is possible to calculate how much extra power a short exposure need in Ampere-seconds, and set up a budget of current drawn based on the above table.
(https://otoien.zenfolio.com/img/s/v-3/p3310729628.jpg)
In this particular calculation I have assumed that the camera stays on for 15 sec at each use. D500 cuts power when battery reports 25% in D7100 (see below), so this must be taken into account with respect to which capacity is available. It is clear that what costs power is not the shutter actuations, which is only a minor fraction, but how long the camera stays on on each use. Also when the D500 is new, and one sit down learning and setting up the menus, one could run the battery down in about 5 hours (How time flies...). So what has been said about mirror-less cameras is also true for DSLRs. (Increase on-time per use to 60 seconds, and the frames per charge will go down dramatically.) Nikon must be taking some liberties when calculating CIPA standard exposures (which is a fairly loose standard). The camera is supposed to stay on for 30 sec for each exposure with screen on, while my calculations will result in the specified 1240 exposures if I set on time per exposure to 21.5 sec and no live view.
A comparison of the battery reporting in D7100 and D500 (inserting the same battery at different charge levels in both) reveals an almost linear relationship between the two, and independent of battery temperature. D500 seems to be more picky on cutoff voltage and will report empty when D7100 reports around 25% charge left. Note that this graph is just a battery meter test and does not imply that D500 use more average power. But the chosen voltage cutoff level might be a consequence of the need to sustain peak current draw. Keep in mind that the single digit series with the same frame rate use a battery with higher voltage. Previous bodies needed a battery grip to achieve this high frame rate while D500 can do without it.
(https://otoien.zenfolio.com/img/s/v-3/p3310729630.jpg)
I also let batteries at two different charge levels cool down for several hours outside before quickly inserting them into D500 and D7100 to check reported battery level:
(https://otoien.zenfolio.com/img/s/v-3/p3310729629.jpg)
The reported charge levels by the battery meters show a nice slow decline down to about -20°C, but then the capacity start to drop off more abruptly. The conclusion is that one should go out with battery fully charged at these temperatures, and not expect to have more than 50% capacity available. It remains to be seen how the D500 will perform below -30°C. The situation might be better than this chart indicates, as the camera usually stays in an insulated bag and takes time to cool down. And in very active use the camera will heat itself too, and might not reach ambient temperature.
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I see that as a beyond worse case scenario for folks like me that live in milder temperature zones. So, those in this area should expect useable battery capacities somewhere north of 50% in cold weather.
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Thank you very much for this very interesting post Øivind.
I would love to understand what is causing my low battery life, as I am not changing any other settings except the ISO?
It could be different batteries, but they are both equally new, and since I always cycle them, they should have done nearly the same number of cycles.
But at some point I will re-run my much less scientific tests using both batteries for both high and low ISO tests.
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Thank you very much for this very interesting post Øivind.
I would love to understand what is causing my low battery life, as I am not changing any other settings except the ISO?
It could be different batteries, but they are both equally new, and since I always cycle them, they should have done nearly the same number of cycles.
But at some point I will re-run my much less scientific tests using both batteries for both high and low ISO tests.
Glad if it can be useful, Peter. I must admit I am a little at loss with respect to your battery life problems at high ISO only. One could think of power consumed by the attached lens, however then the problems would not be fixed by imaging at ISO 400, if the same lens was still in use. An approach would be to do some measurements of the current draw similar to what I did above. You only would need to do static measurements, as the mirror movements is a negligible portion of the energy used during long exposures. A USB power meter could be used for the current draw measurements, but would require the DC-DC converter to get from 5V to 9V, and then there is the problem with buffering the power peaks.
The freezer test would reflect both the current consumption and the battery thresholds. You could possibly check if the threshold is affected by the ISO setting, but it does not seem very likely, and I think I checked that.
I must say that the D500 is a lot more pleasant to work with for astro photography beyond the flip screen. The live view appears more sensitive so that I can use live view directly when focusing with the Bahtinov mask on prominent stars - with D7100 I rarely could see the spikes and had to do test exposures. This also makes it easier to navigate to the target, as more stars to navigate by can be seen. I can in addition see more stars in the viewfinder if I choose to use that.
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I am not an electronics expert at all, but since the lens and camera are set manual focus and VR is switched off the lens would consume very little or no power?
Although to be honest I don't even know if this lens has an electronic aperture (it is the Tamron 15-30mm f2.8 ).
Unfortunately I do not have the tools to measure current draw to these levels, nor do I have the power adapter to provide external power, and since I very much doubt I would use it ever again (almost all my shooting happens away from external power sources), I hesitate to buy one just for a test.
I will test again using both batteries, but to be honest it's not that much of a deal since I have found a method that works sufficiently for my needs.
Thanks again for your assistance!
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If you look at my data above, with AF inactive (I use back button activation) the lens use 80 mA vs 309 mA for the body only during 30s exposure with my 12-24mm. That is about 26% increase in power consumption. I do not think e-aperture matters much - my 300PF actually has lower power consumption. It is hard to say how a third party lens matches up without any empirical data though. But likely the electronics in an advanced lens has to stay on as long as the camera, not only during AF operation. It all adds up, but it is not a factor of two.
It could be interesting to see what it comes out to if you repeat your previous test with the same AIS lens, battery and settings at the problematic high ISO.
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Thanks again
I will report back in due coarse.
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For the record of this thread here are practical shooting results for the D500 that I reported in the Z-system thread (quote slightly edited):
For the Yukon Quest finish I captured 657 frames and the D500 reported 50% battery charge left while still cold (-7°C), 60% after rewarming, most captures short bursts at 10 frames per sec. So at room temperature I would have expected to get 1657 frames if the battery was run to 0%.
Tonight I captured 422 frames at the Ice Alaska (ice carving) festival and the D500 reported 7% battery charge left while still cold (perhaps -10°C at the start, -16°C at the end), 17% after rewarming. Most exposures were on tripod at ISO 100, several seconds long, reviewed almost every frame and I used live view for perhaps 1/4 to 1/3 of the frames - sometimes forgot to turn off live view when moving between sites, actively shooting for a total of > 4 hours. Standby timer mostly on 6 sec. or 30 sec. Flight mode was on and no wifi etc active.
In other words, this is just as expected from our above experiences.