1. What if there isn't a combination of (extension) tubes that equals the optical tube length (in my case, 132.3 mm)? Is that when I would need to add a helicoid to the rig?
2. Does a helicoid feature a lock to fix its length? Otherwise, I’m concerned the microscope objective might shift position when using a macro rig with a helicoid.
Thanks for your advice!
Walter
Helocoid
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- blekenbleu
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Re: Helocoid
A couple of mm tube length error is insignificant with 4x 0.10 objective.
https://www.photomacrography.net/forum/ ... 45#p258045
https://www.photomacrography.net/forum/ ... 45#p258045
Metaphot, Optiphot 1, 66; AO 10, 120, and EPIStar 2571
https://blekenbleu.github.io/microscope
https://blekenbleu.github.io/microscope
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Re: Helocoid
There are non-helicoid adjustable length adapters (they just have long threads) which might suit better for your use.
Re: Helocoid
Normal helicoids for photography don't have locks to fix their length. There are some industrial helicoids that do, from Schneider and Rodenstock iirc. Like scarodactyl said, there are non helicoidal tubes that can be screwed together that allow for very precisely fixed lengths. I have one from RafCamera in 58mm.
But for most use cases a few mm more or less are not a problem.
But for most use cases a few mm more or less are not a problem.