The best infinity-corrected lenses - 1x, 2x, 3x, 4x 5x magnification

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pu5z3k
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The best infinity-corrected lenses - 1x, 2x, 3x, 4x 5x magnification

Post by pu5z3k »

Hello,
I would like to complete the set of infinitely corrected lenses. I currently have a mitutoyo 5x which I am very happy with.
However, I would like something else in the 2-3x magnification scale.

Can You recommend some good lens - with good price ofc :)

Thanks in advance!

Scarodactyl
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Re: The best infinity-corrected lenses - 1x, 2x, 3x, 4x 5x magnification

Post by Scarodactyl »

Microscope objectives below 4x tend to perform poorly, especially compared to other solutions. This is because it's hard to make a low magnification lens parfocal with a high magnification lens--they really want a different form factor.

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Adalbert
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Re: The best infinity-corrected lenses - 1x, 2x, 3x, 4x 5x magnification

Post by Adalbert »

Hi Radek,

Since you already have the Mitu-5x,
I would suggest using a lens with a smaller focal length as TL
to get smaller magnifications.

I very often use the Mitu-5x with a Macro 100mm to get 2.5 magnification.

BTW, but this works perfectly with crop cameras

Best, ADi

ray_parkhurst
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Re: The best infinity-corrected lenses - 1x, 2x, 3x, 4x 5x magnification

Post by ray_parkhurst »

When considering converting my system to infinity type, I've thought about this very topic, but I don't have a definitive answer, just some observations and suggestions to try.

For the Mitty objectives, a 200mm tube lens is appropriate, and it would be nice to stick wtih that tube lens when going to lower mags. For my own purposes, parfocality is unnecessary, and assuming it's the same for @pu5z3k, thus objectives with scaled focal lengths may serve this purpose. So for 1x, 2x, 3x, and 4x, you'd need the following:

~200mm objective
~100mm objective
~67mm objective
~50mm objective

It seems feasible that the 50mm, 67mm, and 100mm could be handled by reversed enlarging lenses. Certainly the Schneider lenses, which seem to match well to tube lenses, would be a good starting point. For the 67mm I'd suggest a 68mm Tominon E36C as it is superb and apo-corrected. Alternatively the 67mm Rodenstock Scitex may do well, though it would be more of a gamble that the tube lens would help to correct that objective's CA issues. The 200mm is more problematic, and I don't have a good suggestion for it. I also don't know how well any lenses will work with whatever 200mm lens you are using, but this seems the easiest solution.

Edited to change OP name. I'm surprised that it's possible to change your username.
Last edited by ray_parkhurst on Fri Jun 24, 2022 8:13 pm, edited 1 time in total.

blekenbleu
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Re: The best infinity-corrected lenses - 1x, 2x, 3x, 4x 5x magnification

Post by blekenbleu »

pu5z3k wrote:
Sat Jun 18, 2022 8:10 am
complete the set of infinitely corrected lenses. I currently have a mitutoyo 5x
Can You recommend some good lens - with good price ofc :)
As has been noted elsewhere, a good infinity lens of some power
can work well at half that power with a suitably shorter "tube lens" focal length.
Specifically, a good 100mm true macro camera lens could provide
both 1:1 with no objective and 2.5x with your Mitutoyo 5x.
Metaphot, Optiphot 1, 66; AO 10, 120, and EPIStar 2571
https://blekenbleu.github.io/microscope

Scarodactyl
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Re: The best infinity-corrected lenses - 1x, 2x, 3x, 4x 5x magnification

Post by Scarodactyl »

blekenbleu wrote:
Tue Jun 21, 2022 7:17 am
As has been noted elsewhere, a good infinity lens of some power can work well at half that power with a suitably shorter "tube lens" focal length.
We've been spoiled by Mitutoyo's generous coverage on this. Most objectives aren't designed to produce a good image that far out, so unless it's known to work well pushed down you can't rely on the extreme edges not being aberrated mush.

Edit: now that I've tested it the Thorlabs 2x super apochromat is probably the best option available at 2x--actually recommendable even.

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