Author Topic: [Theme] Night sky shots  (Read 18049 times)

Řivind Třien

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Re: [Theme] Night sky shots
« Reply #195 on: March 16, 2018, 01:35:09 »
I'm trying to solve the reduced amount of time the tracker is able to handle my front heavy 70-300+D800
At the moment the camera is mounted on the original tripod mount (via an Lbracket)

The objective will be to mount the camera with the center of gravity on the turning axle and therefore reducing the load on the tracker motor, which I would think will improve the precision  and allow longer exposures

I borrowed an image from Řivind and added arrows to show the movement I would need to be able to do with my camera

I found a nodal rail that seems to meet my needs but I'll probably reach to a local fabricator ,  instead of buying it from b&h , and importing it



A quick comment to my own setup: While I find it OK to use the tripod collar of the lens at low altitude angles (the larger than standard clamp on my BH-40 then helps a little with adjusting balance), most of the time, aiming high I have found it better to attach the clamp directly to the camera plate with no collar on the lens. The issue is that the balance of the rig changes depending on the altitude angle.

Another note is that it is important to have the worm drive of the tracker work in "uphill" mode the whole time. This I try to effect by how the ball head is tilted. (That can sometimes be tricky while not also blocking the polar scope). If it is right around the balance point between uphill and downhill mode, slight sloppiness/tolerances in the gears can cause problems. I also pay attention to the cable of my remote and how it drags. (Lately I have attached the remote with Velcro to a tripod leg). I have never really seen evidence that the Skytracker is loaded too much, but then tracking success varies from time to time, so who knows.

When I see images of those counterbalanced rigs (more common in use with some other trackers than the Skytracker), I always wonder about sensitivity to wind and vibrations - it seems like a nice way of creating an oscillating system.
Řivind Třien

armando_m

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Re: [Theme] Night sky shots
« Reply #196 on: March 19, 2018, 04:50:42 »
with my modification to the mounting I was able to do 2' exposures at 300mm

here is the rosette nebula
10 images of 117 secs each (3 seconds used to delay the shutter)

not as spectacular as Orion but it was an interesting challenge

This monitor is a POS ,  I'm looking at the image on my mobile to see if it looks overcooked

Armando Morales
D800, Nikon 1 V1

Ann

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Re: [Theme] Night sky shots
« Reply #197 on: March 19, 2018, 06:29:58 »
Armando:
I am in total awe of your capabilities and the stunning images of the night sky which you have created.

armando_m

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Re: [Theme] Night sky shots
« Reply #198 on: March 20, 2018, 15:04:34 »
Armando:
I am in total awe of your capabilities and the stunning images of the night sky which you have created.
Ann,

Thanks so much for your kind comment

Another target I had that night was the witch head nebula, but I was unsuccessful trying to capture it

For the second half of the night I waited for the milky way to show up, I set the camera with the 20mm lens and left it capturing the sky every 5 mins, here is a time lapse from 3:15 to 5:30
https://youtu.be/C5iHv7DnY0Q
Armando Morales
D800, Nikon 1 V1

Řivind Třien

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Re: [Theme] Night sky shots
« Reply #199 on: March 25, 2018, 07:17:00 »
Great Rosette nebula, Amando and well done tracking for almost 2 minutes!

I was randomly clicking into a 2016 folder after copying to and checking out a new drive when this image showed up. I was fascinated by how the auroral corona and its associated veil covers the southern sky completely, while the northern sky with the big dipper is crystal clear. It was one of those event where one just grabs the camera, runs outside and sets up blindly to get any shots. I was able to fire off three 10 sec exposures, and then it was all gone.


Nikon D7100, 12-24mm @ 12mm and f/4, 10s, ISO 3200
Řivind Třien

Peter Connan

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Re: [Theme] Night sky shots
« Reply #200 on: March 25, 2018, 16:01:21 »
Beautiful!

armando_m

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Re: [Theme] Night sky shots
« Reply #201 on: March 25, 2018, 17:17:03 »
Armando Morales
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Jacques Pochoy

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Re: [Theme] Night sky shots
« Reply #202 on: March 25, 2018, 17:45:06 »
Fantastic...  :)
“A photograph is a moral decision taken in one eighth of a second. ” ― Salman Rushdie, The Ground Beneath Her Feet.

John Geerts

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Re: [Theme] Night sky shots
« Reply #203 on: March 25, 2018, 20:17:28 »
Impressive !

Akira

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Re: [Theme] Night sky shots
« Reply #204 on: March 25, 2018, 22:50:37 »
Awesome!
"The eye is blind if the mind is absent." - Confucius

golunvolo

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Re: [Theme] Night sky shots
« Reply #205 on: March 25, 2018, 23:04:36 »
Impressive, science fiction-like.

Řivind Třien

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Re: [Theme] Night sky shots
« Reply #206 on: March 26, 2018, 11:29:49 »

Thanks all of you for the enthusiastic comments. We actually had some pretty intense aurora last night, but the best was gone before I could get my rig up.

Impressive, science fiction-like.
Some observed some stuff that really sounds like science fiction like over Anchorage yesterday and was reported at Spaceweather.com.  It is a recently discovered phenomenon called STEVE, 'Strong Thermal Emission Velocity Enhancement' and occurs particularly in conjunction with aurora but more at the 60° latitude, so not where it is most intense. It is like a strong light beam across the sky. Here is a citation on the site:
 ' "As the satellite flew straight though 'Steve,' the temperature jumped by 3000°C and the data revealed a 25 km-wide ribbon of gas flowing westwards at about 6 km/s (13,000 mph)," reports Eric Donovan from the University of Calgary.' (emphasis by me) Sounds pretty crazy, I wonder why the satellite did not melt.
Řivind Třien

armando_m

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Re: [Theme] Night sky shots
« Reply #207 on: April 06, 2018, 22:11:45 »
Impressive gigapan of the milky way obtained by the astrophysics institute of the canary islands, the article mentions the pano was created using sony dslrs and canon lenses.

Link to the article http://www.iac.es/divulgacion.php?op1=16&id=1371&lang=en

Link to the gigapan http://gigapan.com/gigapans/207272

I had posted a screen capture of the orion region but the quality is ugly, it is better to click on the gigapan link


Armando Morales
D800, Nikon 1 V1

armando_m

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Re: [Theme] Night sky shots
« Reply #208 on: April 16, 2018, 19:55:30 »
20x1min exposures to capture the great Orion nebula
I'm delighted I was able to capture this after driving only 1 hr away from home, 70+ kms, at an altitude of 2200m.

For capturing the image I use the iOptron sky tracker, this is an equatorial mount that counter acts the earth rotation and therefore long exposure can be taken avoiding star trailing, care should be taken to have the tripod level and then aligning the mount towards the north star.

It has been discussed here before but to obtain this kind of images i use a program called deepskystacker, freeware for windows, besides the light frames ( that is the actual photos of the object being captured) a number of other photos are used to reduce noise:
- dark frames, taken with the same exposure as the light frames, but with the lens cap on, it is important to shoot this right after the light frames, so the sensor is at the same temperature as the light frames, these are used to detect noise levels, and hot pixels
- offset frames. again with the lens cap on same ISO as light frames, shot at the highest shutter speed , 1/8000 for the D800
- flat frames, used to correct vignette, shot of a clear surface at the correct exposure, the sky works well if it is clear
deep sky will produce an image that often needs adjustments to get anything visible, I save this to a 32 bit TIF.
I'll continue post processing in PS, using ACR to convert the TIF to 16 bits, it works like an HDR image, with lots of flexibility, truly amazing

Since our eyes do not see the colors captured by the camera, post processing color is completely up to you.

This is my third time shooting Orion, last year in January, this year in February, both times in a very dark location,  and just recently on Apr 14 in a location just 70kms from a large city with lots of light pollution, not ideal, but it worked well even with a fairly short exposure of 20 minutes

Also worth noting, and this is a heavy crop from the 36mp image I'm only using 910 x 910 pixels
Armando Morales
D800, Nikon 1 V1

Peter Connan

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Re: [Theme] Night sky shots
« Reply #209 on: April 16, 2018, 20:17:56 »
Stunning shot Armando!