5x with a budget rail and tripod?

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joshmacro
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Re: 5x with a budget rail and tripod?

Post by joshmacro »

Chris C wrote:
Wed Oct 05, 2022 4:34 am
Thanks for linking to this!! If I understand correctly, using the rear bellows would enable 25x larger step size at 5x magnification.
I expect that for my particular case though, it then makes no net difference. My rail gives a 1mm step per rotation and the bellows a 25mm step according to the linked post, which is again a 25x ratio. This exactly cancels the advantage of the bellows, so with my rail I would be similarly capable of doing the necessary small steps in focus.
Your math may be off a bit, but I understand your point. The reason why bellows was brought up is that it's a flexible way of attaching finite objectives to your camera. You can move the bellows to adjust magnification (within limits of the objective). This flexibility combined with the ability to use rear stepping makes the bellows at this magnification range very easy to use.

Chris C
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Re: 5x with a budget rail and tripod?

Post by Chris C »

joshmacro wrote:
Wed Oct 05, 2022 4:30 pm
Your math may be off a bit, but I understand your point. The reason why bellows was brought up is that it's a flexible way of attaching finite objectives to your camera. You can move the bellows to adjust magnification (within limits of the objective). This flexibility combined with the ability to use rear stepping makes the bellows at this magnification range very easy to use.
.

That's a very good point. If I'd get a finite objective, I'd need some more empty tube anyway to use it. That tube may well be a convenient bellows system which would give some more flexibility.

Does anyone have a suggestion for an affordable objective of approximately 5x, 0.14 NA, that may be shipped to The Netherlands.

blekenbleu
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Re: 5x with a budget rail and tripod?

Post by blekenbleu »

Chris C wrote:
Thu Oct 06, 2022 7:14 am
Does anyone have a suggestion for an affordable objective of approximately 5x, 0.14 NA, that may be shipped to The Netherlands.
Nikon made a Plan 4/0.13 that is generally available, e.g. https://www.ebay.nl/itm/385111211651
.. but see also https://www.photomacrography.net/forum/ ... 96#p277496
"On APS-C, the sharpest "5X" in my kit is an infinity 10X pushed down on 100 mm tube lens, and the sharpest "10X" is a 20X infinity pushed down in the same way."
Metaphot, Optiphot 1, 66; AO 10, 120, and EPIStar 2571
https://blekenbleu.github.io/microscope

Chris S.
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Re: 5x with a budget rail and tripod?

Post by Chris S. »

I would also be looking at that Nikon 4x/0.13 for this application. (I have an Nikon apo 4x/0.20 that I quite like, but it costs much more.)

Regarding the use of a 10x infinite objective pushed down to 5x with a shorter converging lens, I'd mention that a typical 10x numerical aperture of, say, 0.30 will bring with it some of the added difficulty of a 10x objective, even if it is used at 5x. That is, the step size will need to be smaller--perhaps 5 microns instead of 20 microns. And the additional resolution of an NA 0.30 objective will make vibration apparent that might not be seen at NA 0.14. So if Chris C is concerned about using his rig at 10x, pushing a 10x objective down to 5x may still be problematic.

--Chris S.

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