Bellows on Wemacro Rail

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robwat
Posts: 20
Joined: Fri May 04, 2018 12:49 pm
Location: Peebles UK

Bellows on Wemacro Rail

Post by robwat »

Just wondered if anyone was using bellows with microscope objective on a wemacro rail. I have set this up but it is quite high and looks ungainly. I have not tried it yet but think it will increase vibration risk. Grateful for any comment.
Thanks
Bob

ray_parkhurst
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Location: Santa Clara, CA, USA
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Re: Bellows on Wemacro Rail

Post by ray_parkhurst »

robwat wrote:
Fri Jan 27, 2023 7:02 am
Just wondered if anyone was using bellows with microscope objective on a wemacro rail. I have set this up but it is quite high and looks ungainly. I have not tried it yet but think it will increase vibration risk. Grateful for any comment.
Thanks
Bob
I built a system for a coin photography forum member that utilized a bellows mounted to an arca plate. Later he bought a StackShot rail and tried adding it to the system with very little success due to the increase in vibration amplitude and longer settling time. I had earlier built an "idler" system based on the WeMacro stand and it was very successful, so I worked with him to fix the problem by implementing similar concepts, and it worked well. I'll give some info on the projects below.

The main driver of improvement is the "idler" rail concept, which adds a passive "idler" rail to stabilize the automated rail against "pitch" torque/moment due to the weight of the moving elements. The result is a dramatic reduction in vibration amplitude and settling time, with a secondary benefit of providing a large and stable moving platform for mounting the bellows, lighting, etc.

Here is the original WeMacro system with added idler:
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WeMacro Rail v2_1.JPG
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Note the bellows is not shown, but would mount onto the moving arca rail/plate.

What bellows are you using? Some bellows have large moments on their own, and can be improved.

Here is a drawing of the conversion of a StackShot to add the idler. This is the drawing I sent to the coin forum member, and he built it pretty much as I drew it. I think I have a pic of his finished system somewhere if anyone is interested.

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System9wStackShotv3_1.JPG
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Note the drawing shows the system as horizontal, but the final system was vertical. The idler concept works well in any orientation. As an example I built a horizontal system for a PM forum member that was based on a THK KR20 with added THK Idler rail. Below are the original drawing I made, and the final product.

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Horizontal Setup v1_1.JPG
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DSC_3995_2_1.JPG

robwat
Posts: 20
Joined: Fri May 04, 2018 12:49 pm
Location: Peebles UK

Re: Bellows on Wemacro Rail

Post by robwat »

Hi Ray,
Many thanks for the info that looks fantastic. I have attached photos of my current setup for info. I have mounted the arca rail on a timber board whci is great if I am just using the bellows. I do also have the wemacro stand which I tend to keep as a vertical. Am I correct in thinking that the parts required to build your rig are generally available.
Thanks
Bob
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20230128_092441.jpg
20230128_092419.jpg

lothman
Posts: 959
Joined: Sat Feb 14, 2009 7:00 am
Location: Stuttgart/Germany

Re: Bellows on Wemacro Rail

Post by lothman »

ray_parkhurst wrote:
Fri Jan 27, 2023 8:27 am

The main driver of improvement is the "idler" rail concept, which adds a passive "idler" rail to stabilize the automated rail against "pitch" torque/moment due to the weight of the moving elements. The result is a dramatic reduction in vibration amplitude and settling time, with a secondary benefit of providing a large and stable moving platform for mounting the bellows, lighting, etc.
I agree with the idler setup, I use it myself. I don't use a wemacro rail but it should be fairly easy to get two linear ball bearings, design an idler block which can be mounted into the wemacro rail and run it as a complete unit. Of course you would loose some stroke length but I think most of us rarely need more than a 20mm deep stack.

@robwat
when you bolt the wemacro rail direct to the base plate and then your bellows direct to the wemacro rail, you would reduce several chances of wobbling interfaces (IMO those 2 Arca rails are without benefit) and on the other hand reduce the distance/lever of your camera to the bearings of the rail. This will decrease deflections and wobbling.

robwat
Posts: 20
Joined: Fri May 04, 2018 12:49 pm
Location: Peebles UK

Re: Bellows on Wemacro Rail

Post by robwat »

Thanks Lothman I will give that a try

ray_parkhurst
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Re: Bellows on Wemacro Rail

Post by ray_parkhurst »

robwat wrote:
Sat Jan 28, 2023 2:37 am
Hi Ray,
Many thanks for the info that looks fantastic. I have attached photos of my current setup for info. I have mounted the arca rail on a timber board whci is great if I am just using the bellows. I do also have the wemacro stand which I tend to keep as a vertical. Am I correct in thinking that the parts required to build your rig are generally available.
Given the complexity of your system, I'm not at all surprised you're having issues. @lothman has given a good suggestion to eliminate the unnecessary adjustment rails and clamps. It may be that what you end up with is acceptable, though IMO it still has major potential for problems based on the results from my earlier WeMacro and StackShot modifications. In both cases the moving rail carriage was the culprit in the vibrations, in combination with the weight and distance (moment) of the camera versus the rail carriage.

The linear rails I show in the diagrams and pictures are readily available, as are the spacers, but some work is required to put it all together. Better to try @lothman's suggestion first, especially since that path would be part of the solution with the idler anyway.

Edited to add: in my own setups, after stabilization with idler rails, the next biggest factor in vibration has been the bellows focus rail.

robwat
Posts: 20
Joined: Fri May 04, 2018 12:49 pm
Location: Peebles UK

Re: Bellows on Wemacro Rail

Post by robwat »

Would it be simpler not to use bellows on the Wemacro rail and use tubes instead this would take one level away

ray_parkhurst
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Location: Santa Clara, CA, USA
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Re: Bellows on Wemacro Rail

Post by ray_parkhurst »

robwat wrote:
Sun Jan 29, 2023 6:03 am
Would it be simpler not to use bellows on the Wemacro rail and use tubes instead this would take one level away
It depends on how you implement the camera mounting. Mounting the camera by its tripod mount is notoriously unstable. If you can use a secondary tripod mount on the extension nearest the objective, or perhaps use tripod mounts either end of the extension stack, that would be better. An example would be the WeMacro tube lens. With something like that system, the moment arm is greatly reduced.

robwat
Posts: 20
Joined: Fri May 04, 2018 12:49 pm
Location: Peebles UK

Re: Bellows on Wemacro Rail

Post by robwat »

Thanks Ray I have just ordered the wemacro tube lens assy

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