NikonGear'23
Gear Talk => Lens Talk => Topic started by: CS on July 10, 2017, 20:19:16
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But others are encouraged to respond too.
Not long ago, I remarked about a friend of mine going to Oregon next moth to capture the upcoming eclipse of the Sun. He's using 4 camera setups, but this is about one of them, his D7200/80-400 (first model) mounted on a tracking device arm. He's having vibration issues, says that the tracker is vibration free, so it looks like they are all from the shutter, through that lousy tripod collar.
I referred him to your Tripod Collar Blues article from 2002. Then I though I'd ask you if you had any specific advice for that setup with the 80-400 hung out there in outer space? I'm including an image of his setup in case it helps.
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Wow, the collar is the weakest link in the true sense of the word in the setup...
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I forgot to add that he will be hanging about 10 lbs of weight on the tripod to aid stability which he says is rock solid to begin with.
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Wow, the collar is the weakest link in the true sense of the word in the setup...
Absolutely! OTOH, he is doing what he can to make the best of the situation. I measured the diameter of an asthma inhaler, 13/16ths, in case that dimension works (wrapped with foam, of course) for his 80--400. ;)
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Not even hanging 100 kg of stone under the tripod would help in the slightest. The weak point is glaringly obvious: the tripod collar of the lens. The added lateral leverage just makes the situation worse.
An additional support for the camera or lens is urgently required. A simple approach would be to drop the flimsy tripod collar entirely and use gaffa tape (or straps?) to fasten the lens directly to the tracker. First put a longer plate on the tracker head to provide a better mounting surface.
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Not even hanging 100 kg of stone under the tripod would help in the slightest. The weak point is glaringly obvious: the tripod collar of the lens. The added lateral leverage just makes the situation worse.
An additional support for the camera or lens is urgently required. A simple approach would be to drop the flimsy tripod collar entirely and use gaffa tape (or straps?) to fasten the lens directly to the tracker. First put a longer plate on the tracker head to provide a better mounting surface.
Thanks. Bjørn, I'll pass your info on to my friend. He's doing a lot of testing now in order to be ready for the event, and I'm sure that he will be glad for the help. 8)
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A screw on industrial clamp should do for the moment. Put some insulation between the lens tube and the clamp
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A screw on industrial clamp should do for the moment. Put some insulation between the lens tube and the clamp
Thanks, Frank, sounds like a good suggestion.
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I would make a lens cradle to hold both the lens and camera together on one plate of tempered aluminum as one unit. The fit needs to be perfect so the lens and camera are not under stress when it's all tightened down. I'd secure this to the bottom of the lens cradle with two screws and maybe JB Weld Wimberley P30 Quick Release Plate (https://www.bhphotovideo.com/c/product/205335-REG/Wimberley_P_30_P30_Quick_Release_Plate.html). The lens collar would probably be made of a couple of pieces of bar stock. I'd screw and JB Weld them together. You'll want as few surfaces a possible where there is any play, even minute.
I'd use a Wimberley C-30 Quick Release Clamp (https://www.bhphotovideo.com/c/product/205331-REG/Wimberley_C_30_C_30_Quick_Release_Clamp.html) on the plate added to the tracker. I'd secure the C-30 with two screws. It's more money but I'd use a RRS or Kirk L-Plate on the camera. The L-plate cradles the body so there isn't only a small rubber cushioned contact area. I would probably secure the camera L-plate and lens tripod collar directly to the lens cradle. I'd use a plate on the tracker head with two screws into the C-30 clamp. I'd use a safety stops and a safety cable.
Does anyone make a replacement lens collar for the lens. The lens collar looks terribly weak. I'd rather start with a better collar if possible.
I've thrown this down rather quickly as Ideas I'd start with. I have to run.
Dave Hartman
Below is an example of a lens cradle. The aluminum blocks are held together with four screws and JB Weld to be double sure of the integrity of the unit. To assure a good bond I cleaned the parts with acetone before assembling. If the unit with the PN-11 were to fail with a 105/4.0 AI, PN-11 and dSLR all would hit the ground. It would be nice to have a machine shop and skills to mill the unit out of one block of aluminum.
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When I point my 300mm PF high in the sky on my tracker, I do not use the tripod collar at all (even if it is pretty decent), I just use the plate on the camera. That gives better balance. I am not sure if angle of the sun is high enough for the eclipse though. The suggestion with dual attachment point to the camera plate and the collar sounds like a good one. For high alt. angles, one would want to bring the attachment point towards the body away from the lens collar.
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In Oregon, the angle of the sun above the horizon at the time of totality will vary from 40 degrees at the coast to 45 degrees at the Idaho border. This will continue to increase eastward, up to about 61 degrees when the umbra reaches the Atlantic Ocean.
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A possible alternative solution is to replace the SLR with a mirrorless camera. But...I have not used the lens in question. If the tripod
mount collar of that lens is really bad, mirrorless may not help.
Example: If I use my 300/4 AF-s(fitted with Kirk aftermarket tripod mount collar) and a D800 + small Gitzo CF tripod w/RRS BH-55 head, I dependably get ruined images via camera shake at the "danger zone" shutter speeds. If I swap out the D800, and instead use the same lens and setup with the lowly Fujifilm XE-1(on Novoflex FUX-NIK adapter), the camera-induced shake is gone.
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I would buy a long Arca compatible rail, 300 or 400mm, fix it on camera and carve 1 or 2 pieces of wood to support the lens, screw them to the rail and apply large amount of gaffa tape everywhere possible. These rails do have many holes for screwing and additional rigidity can easily be gained by screwing 2 rails together or by screwing additional metal plates to the rail.
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I see CS, your call gets the creative juices flowing.
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I would buy a long Arca compatible rail, 300 or 400mm, fix it on camera and carve 1 or 2 pieces of wood to support the lens, screw them to the rail and apply large amount of gaffa tape everywhere possible. These rails do have many holes for screwing and additional rigidity can easily be gained by screwing 2 rails together or by screwing additional metal plates to the rail.
This is a promising idea that isn't highly expensive.
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I would buy a long Arca compatible rail, 300 or 400mm, fix it on camera and carve 1 or 2 pieces of wood to support the lens, screw them to the rail and apply large amount of gaffa tape everywhere possible. These rails do have many holes for screwing and additional rigidity can easily be gained by screwing 2 rails together or by screwing additional metal plates to the rail.
What am I missing here? Arca compatible brackets for cameras and lenses run perpendicular to one and another, so how would one rail work for both camera body and lens?
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The idea, as I understand it, is that the camera and lens would be directly screwed to the rail, rather than placed in Arca type clamps.
However, the camera and lens will inevitably mount at different heights from each other. I propose just securely mounting the lens...via one or two sculpted wood blocks... only to the plate. A additional clamping piece, either metal hose clamp(s) or a matching sculpted wood block would need to used to secure the lens downward to the bottom wood block and the rail below. A crude concept sketch:
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I don't have any collared lens experience, but wouldn't the wooden blocks block zoom and focus control rings?
I thought that Bjorn's remedy was to clamp down from the tripod collar area of the lens leving the controls accesible.
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The lens cradle shown above is for a PN-11 and additional extension tubes. What I suggest above would join a dSLR L-Plate and lens collar in a similar way.
Dave
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The idea, as I understand it, is that the camera and lens would be directly screwed to the rail, rather than placed in Arca type clamps.
Exactly, and indeed a block under the camera to keep the lens from sliding axially. The gaffa tape helps also in that respect. Thanks for clarifying, Keith.
I don't have any collared lens experience, but wouldn't the wooden blocks block zoom and focus control rings?
There is space between the 2 rings and I would remove the collar anyway. You don't need the block to be large to stop vibrations. A L shape would provide enough space for screwing on the rail and a thinner support between the rings or on the collar space.
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I passed on the info to my friend and here's where he is on this:
"I’m thinking of designing my own front and rear support system. I’d have to get the three pieces machined.
It would mean giving up horizontal alignment, which was an original constraint, but I can do Polar alignment instead.
The real issue is figuring out all the measurements - I need to see if the tripod mount-to-sensor centerline is published anywhere. If not, I’ll need to measure, machine everything a bit small, and use shims."
I dunno if anyone can tell me the "tripod mount-to-sensor centerline" measurement, but perhaps Bjørn or Roland might have it.
Thanks to everyone that has responded, it all helps.
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Thinking out loud so to speak, on Bruno Schneider's idea, if the long Arca plate has 1/4 inch threaded holes in it especially, one might be able to get screws and threaded collars. There exist collars, that are essentially a tube an inch or two tall, threaded internally,used to join two pieces of threaded rod together. One of these and a couple of screws can make a sort of inverse turnbuckle, in which the lower end is screwed directly to the pad, and the upper end screwed out to provide pressure. Put a rubber cap or the like on the head of the upper screw, and raise it until it presses on the lens barrel. Do that at a couple of different places, and it should keep the lens from rocking on the mount.
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Posting error.
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What am I missing here? Arca compatible brackets for cameras and lenses run perpendicular to one and another, so how would one rail work for both camera body and lens?
The plates generally have a 1/4-20 fitting or two so they can be attached to a long Arca-Swiss lens plate using those features. Spacers would most likely be needed to line the lens collar and camera or camera L-pate. Care is needed to see that there is no stress on the bayonets. I'd use 6061-T6 bar stock though if wood working equipment is available hard maple should work well.
Dave
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He has come up with his own design, and sent me a couple of PDFs, but they don't copy and paste here well.
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Seems like rubber and gaff tape should be avoided if possible, since they are not rigid.
Carl, if your friend doesn't mind showing it here, copy the PDF as a small (sub-megabyte range) JPEG and it'll post right up.
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Seems like rubber and gaff tape should be avoided if possible, since they are not rigid.
Carl, if your friend doesn't mind showing it here, copy the PDF as a small (sub-megabyte range) JPEG and it'll post right up.
Send me you email address and I'll email it to you. Can't seem to get it posted.
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Lets try this again. Here's the pdfs of his design that he sent to me yesterday.
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Finally! Converting pdf to jpg was the culprit. Thanks for the suggestion, Keith, that did the trick.
My friend has a friend with a CNC machine, so he is going to ask for a quote to get the pieces fashioned, then he will drill and tap them at home.
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I have a cheat, though probably not as good:
Insert a suitably trimmed wine bottle cork between the lens and the foot.
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I have a cheat, though probably not as good:
Insert a suitably trimmed wine bottle cork between the lens and the foot.
I like that one, Peter. It's very close to Bjørn's asthma inhaler, but easier to trim to fit, if necessary. Not that I have anything against more permanent solutions, such as an actually effective tripod collar. Necessity being the mother of invention, it's always interesting to see what others come up with.
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Really Right Stuff,......It's the "Bomb."
I bought one via auction. (The seller didn't know what it was & I practically stole it.) The detachable foot also works with the 70-200VR, version 1.
The 80-400VR works well with my rigs. I cannot justify ponying up for the Af-S version..... (& yes....I lost my shirt on value of the relic.
It's all good,
Steve
:) :) :) :) :) :) :) :) :) :)
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Feisol has a lens plate that is Arca Swiss compatible and can be fixed to the camera bottom:
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Just be very cautious about putting too much lateral pressure on the camera mount. The cradle principle can add significant leverage to any force applied.
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HejnarPhoto makes adjustable lens supports in different sizes: http://www.hejnarphotostore.com/category-s/103.htm (http://www.hejnarphotostore.com/category-s/103.htm)
If necessary it should be possible to add some sort of strap to keep the lens in contact with the wheels even when turned vertical.
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He likes the looks of the Kirk AF-D replacement collar, but he's is also considering the homemade design that I posted. An issue with many solutions is that they restrict focus and zoom control in their effort to clamp down on lens movement.
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He likes the looks of the Kirk AF-D replacement collar, but he's is also considering the homemade design that I posted. An issue with many solutions is that they restrict focus and zoom control in their effort to clamp down on lens movement.
He should probably get the Kirk replacement collar for all use of the lens. I'd just get it and then see if more stabilization is needed for this special application.
Dave
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I would doubt the effect of the Kirk-style collar when the lens is set almost perpendicular to the ground.
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I would doubt the effect of the Kirk-style collar when the lens is set almost perpendicular to the ground.
I tend to agree with that. Collars are designed to be vertical with lens and camera rotating when portrait is needed. The barycentre is then on the plate axis with the plate flexion in its longest dimension. When mounted as shown on the first picture, the flexion arm is lateral with the barycentre far away from the plate, inducing torsion on the plate on the smallest dimension. This is the worst case scenario.
To reduce vibration, the barycentre should be as close as possible to the plate, which is why I would get rid of the collar and build a custom mount with at least supports in 2 places. Using a long rail also allow to position the barycentre closest to the plate by sliding it on the head. If the barycentre is correctly placed with the lens zoomed and focused, no need for that of course but you can only check with the real camera and lens properly focused and zoomed on hand.
Last point, long rails are different in design, I would favour one with many bolt holes, to get more flexibility in positioning the custom blocks, like the one below
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My friend has modified design that I posted the other day, and that is what he's going with.
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The tripod collar re-design for the 80-400 has been completed, and testing is underway. The testing has been hampered by our annual monsoon weather here creates clouds that blocks views of the heavenly bodies, but he finally got some clear sky and I'll post images tomorrow, along with his plan of action. Too late to get into that today.
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Here's the new tripod collar design for the upcoming eclipse.
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Below is the text of an email from my friend that explains much of what he is planning. The new collar has removed the vibration issue:
"I am using a very sophisticated piece of OS X shareware called “Solar Eclipse Maestro” to control the cameras:
http://xjubier.free.fr/en/site_pages/solar_eclipses/Solar_Eclipse_Maestro_Photography_Software.html
This software, which Xavier Jubier has been working on since the OS 9 days, is pretty much the defacto tool for eclipse photography, especially with Nikon cameras.
The software supports direct camera control via scripts, and the scripts are referenced to notable eclipse times (like “C2”, when the moon first fully eclipses the sun). Since these events are strongly influenced by your location, the software gets accurate time and location information from Bluetooth or USB GPSs. This way, you can write scripts to do the imaging without having to worry too much about where you will be viewing the eclipse from.
In my case, I will be scripting 3 cameras:
1) The D5100, which will be used as a time-lapse movie camera. I need the script to ramp both the exposure and the FPS rate as totality approaches.
2) The D7200, which will be my primary camera for taking solar close-ups. The script will take exposures every few minutes before totality, to capture the partial phases, and then take big bursts of images at a huge range of exposures from right before totality to right after, and then go back to taking partial phase iamges
3) The D800E, which will be used as a landscape camera, taking images every few minutes and then multiple images at totality at different exposures.
I also have another D800E, which will have a 35mm lens on it, and I am going to shoot that manually, for backup and panoramas.
Since we finally had a clear night, I tested the new camera mount tonight. I think it is working about as well as I could expect.
Here is a 1/8 second at f/8 moon shot:
I don’t think there is any vibration-induced blur at all. Any residual unsharpness is unavoidable atmospheric distortion, lens unsharpness, and diffraction.
The camera and lens are supported in 3 places. I had to shim the front lens mount and the camera mount to get everything in line.
Note the chunk of steel glued to the front for balance."
In a later post he says:
"Yes, SEM is quite an impressive program. There are lots of features I won’t be using, which are used by professional astronomers.
I worked on the tracker a bit more today. I thought of a way to take some of the error out of the alignment, and I am testing it now. So far, I’ve been able to keep the sun in the frame for around 2 hours, which is good enough for me. I’m also testing the focus drift with temperature. Seems OK, but I need to do it again in the morning, so I can get more heating.
USB camera control is pretty much an afterthought on most DSLRs. The D5100 is particularly bad - the interface won’t accept another command until the first one is processed, including being written to SD.
You can do long bursts, because that is considered one command, but there is a limit to how many frames (100). If the burst was unlimited, I would use it. But, I don’t want to take 100-shot bursts, and then have to wait and take another 100-shot burst. That gap would be annoying. "
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I'm surprised at the lack comments on the final design of the camera/lens mount solution for shooting the eclipse.
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Sorry for that, Carl, holiday time and smartphone reading/writing .... Thanks for the info, the software link and the pictures. It is very interesting to see the final set up, I did not expect it to be like that. I did not realise the camera would be that far back relative to the head. Any reason for that?
Your friend's set up is impressive. I'm eagerly waiting to see the pictures.
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Maybe the rest of the front part of the plate work as counter weight to cancel the weight of the camera? But isn't there any possible flare caused by the reflection of the sunlight from the plate? I wonder if the reflection is ignorable enough because of the extremely dense ND filter to shoot the sun?
So long as there is no mechanical stress between the inner barrel and the outer barrel of the zoom, the fixture looks fine.
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Sorry for that, Carl, holiday time and smartphone reading/writing .... Thanks for the info, the software link and the pictures. It is very interesting to see the final set up, I did not expect it to be like that. I did not realise the camera would be that far back relative to the head. Any reason for that?
Your friend's set up is impressive. I'm eagerly waiting to see the pictures.
I don't know the exact reasoning behind the camera position, Bruno, but I will ask.
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Interesting solution. I agree about the potential for creating glare into the front element, but a long sun shade on the lens and/or felt flocking of the outer metal part should alleviate such issues.
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Maybe the rest of the front part of the plate work as counter weight to cancel the weight of the camera? But isn't there any possible flare caused by the reflection of the sunlight from the plate? I wonder if the reflection is ignorable enough because of the extremely dense ND filter to shoot the sun?
So long as there is no mechanical stress between the inner barrel and the outer barrel of the zoom, the fixture looks fine.
There is a steel bar for counter weight on the front of the mounting plate.
I will ask, Akira. I do know that in the moon shot that I posted yesterday, the moon was so bright that it necessitated a 6 stop ND filter on the lens.
He used shims to set the alignment. If he loosens the screws that clamp front collar together, then he can set the focus. Once locked down no telescoping is allowed between the inner and outer barrels, even pointed at 90˚.
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Maybe the rest of the front part of the plate work as counter weight to cancel the weight of the camera? But isn't there any possible flare caused by the reflection of the sunlight from the plate? I wonder if the reflection is ignorable enough because of the extremely dense ND filter to shoot the sun?
Here's his response your questions, Bruno and Akira:
"This is correct - I left the extra length at the front for 2 reasons -
1) With no extra length, the C.O.G. is pretty much right under the existing tripod mount on the 80-400mm lens. I need to move the C.O.G. forward to have a place to drill the holes for the tracker mount.
2) I wanted the entire assembly to be as massive as practical, to give the whole system extra damping.
In practice, I will be using the lens hood on the 80-400mm lens, and the front of the mount is out of it’s field of view, so I’m not too worried about reflections (I did move the chunk of iron counterweight to the back, in an over-abundance of caution). But, one can’t be too careful, so I’ll hit it with some matte black spray paint later today…"
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I will ask, Akira. I do know that in the moon shot that I posted yesterday, the moon was so bright that it necessitated a 6 stop ND filter on the lens.
He used shims to set the alignment. If he loosens the screws that clamp front collar together, then he can set the focus. Once locked down no telescoping is allowed between the inner and outer barrels, even pointed at 90˚.
Thanks, Carl, for forwarding my questions to the owner.
I think the brightness of the moon and the sun is totally incomparable. A 6-stop ND filter reduces the light to 1/64 whereas the ND filter for shooting the "normal" sun does that to 1/100000 (which was what I used to Transit of Venus a few years ago). To shoot the moment of the total eclipse wouldn't need a 1/100000 ND,
To eliminate the reflection from the plate, putting a rippled plate like a wash-tab might work better than the black paint or a sheet of felt.
As for the clamp, I was concerned about the bending force between the inner barrel and outer barrel when the inner barrel zoomed out is locked. In order to minimize this bending power, the center of the outer barrel and that of the inner barrel should be perfectly aligned when the clamp is tightened. Otherwise, the lens can be damaged, or at least the image quality would suffer. That said, the owner should already know about these potential problems of the rig.
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I don't like the look of all that aluminum sticking out in front. It can do any good for flare. An ND filter makes no difference. The ND will reduce both image forming light and non- image forming light. The ratio will be constant. The mass surely is enough to make a difference. If more mass is needed it can be add easily another way.
To black the bracket VHT Case Paint adheres well to clean aluminum. I've used it on negative carriers and it stands up well to heavy use over many years. A groved surface would be better than a flat one. Cutting it off would be better unless so use other than mass is for seen.
Dave
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Thanks, Carl, for forwarding my questions to the owner.
I think the brightness of the moon and the sun is totally incomparable. A 6-stop ND filter reduces the light to 1/64 whereas the ND filter for shooting the "normal" sun does that to 1/100000 (which was what I used to Transit of Venus a few years ago). To shoot the moment of the total eclipse wouldn't need a 1/100000 ND,
To eliminate the reflection from the plate, putting a rippled plate like a wash-tab might work better than the black paint or a sheet of felt.
As for the clamp, I was concerned about the bending force between the inner barrel and outer barrel when the inner barrel zoomed out is locked. In order to minimize this bending power, the center of the outer barrel and that of the inner barrel should be perfectly aligned when the clamp is tightened. Otherwise, the lens can be damaged, or at least the image quality would suffer. That said, the owner should already know about these potential problems of the rig.
I wasn't comparing shooting the moon with shooting the sun. I mentioned the 6 stop ND filter as an aside to the main topic, the eclipse, because it isn't obvious when viewing the moon images.
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The angle to the sun will all but eliminate flare from the top face of the plate because the sun will not be looking at the top surface of the plate, but the front edge instead. But, he has added the felt to the face anyway.