Best 40 -60 x lens (infinity corrected) on fullframe

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Kurt24
Posts: 4
Joined: Thu Feb 25, 2016 4:20 am
Location: Germany

Best 40 -60 x lens (infinity corrected) on fullframe

Post by Kurt24 »

Dear all,
I'm currently using Mitutoyo lenses ( M Plan Apo 5 x HR, 10 x, 20 x) and the Mitutoyo M Plan Apo 50x. All are used with a 200 mm tube lens, which covers fullframe quite well. Although the M Plan Apo 50 x is a good lens, I'm searching for an alternative for it, because its numerical aperture is quite low. It "just" results in a t stop of approx. 45. Consequently, on a full frame camera a lot of diffraction is limiting the image quality.

Which alternative lens is worth looking into? I'd be happy to see your findings (i.e. with 100 % crops from middle and the corners). Or just your thoughts. I don't want to invest into something, which turns out to be not really suitable.
I found the Mitutoyo M Plan APO 50x HR, which has an aperture of 0.75 and accordingly a t stop of 33. I can imaging, that this is fine. The free working distance is low (5-6 mm) but that should be doable with my lighting setup. But I couldn't find images or a test.

Just for clarification: I have no need to stick to Mitutoyo!

Cheers,

Kurt
Last edited by Kurt24 on Mon May 17, 2021 12:13 pm, edited 1 time in total.
Best regars,

Kurt

Scarodactyl
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Re: Best 40 -60 x lens (infinity)

Post by Scarodactyl »

What kind of working distance do you need? It's easy to get good 50x objectives if you don't mind ~1mm of working distance.

Kurt24
Posts: 4
Joined: Thu Feb 25, 2016 4:20 am
Location: Germany

Re: Best 40 -60 x lens (infinity)

Post by Kurt24 »

Hi,
I think something around 5 mm ist fine. I imagine much less becomes problematic for what I want to do. I'd like to photograph (stack) scales of butterfly wings.

Cheers,

Björn
Best regars,

Kurt

Adalbert
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Joined: Mon Nov 30, 2015 1:09 pm

Re: Best 40 -60 x lens (infinity)

Post by Adalbert »

Hi Kurt,
For the scales the WD=1mm is OK. So Olympus 50x / 0.80 can be used:
E.g. viewtopic.php?f=27&t=42944
Best, ADi

Kurt24
Posts: 4
Joined: Thu Feb 25, 2016 4:20 am
Location: Germany

Re: Best 40 -60 x lens (infinity)

Post by Kurt24 »

Hi,
ok. Can you give some advice / hints how you did the lightning with just 1 mm working distance.

Do you now whether this lens is able to produce a image circle big enough for fullframe. I've seen that you're using a Canon M6 mII, which has a smaller sensor.

BTW: Which exact lens is it?

Cheers,

Björn
Best regars,

Kurt

Adalbert
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Re: Best 40 -60 x lens (infinity corrected) on fullframe

Post by Adalbert »

Hi Kurt or /and Björn,

Please take a look at that;
viewtopic.php?f=25&t=42924&hilit=50x+%2F+0.80
The name of the oly is: UMPlanFl 50x / 0.80 ∞ / 0
It is Ok for for the crop but you get some vignetting at FF :-(

Illumination like that:
https://www.facebook.com/photo?fbid=120 ... 0269581589

Best, ADi

Macro_Cosmos
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Re: Best 40 -60 x lens (infinity corrected) on fullframe

Post by Macro_Cosmos »

UMPlanFl objectives are as the name indicates semiapochromats/fluorites, you will see CA especially with high contrast colours, white for example. Not hard to fix though. MPlan objectives are better, slightly. UIS objectives have a field number of 22, so you will see vignetting with FF. UIS2 ones (Fn=26.5), not so much vignetting but the corners aren't great either way, you will want to crop them out. Apochromatic 50x and 100x UIS/UIS2 metallurgical objectives' WD=<1mm, usable though. I've taken some decent scale shots with my 100x.

My opinion would be to just stick with Mitutoyo. You might want high NA but you probably also want controllable light and that's preferable in my opinion. With these tiny WD objectives, you're either blasting the subject with light or using coaxial epi-illumination. Very flat light, sometimes uninteresting -- as in all the photos look the same and inevitably lacks character; additionally, highly subject dependent. (Feel free to disagree, I'm only referring to my own experience and my own work.)

Scarodactyl
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Joined: Sat Apr 14, 2018 10:26 am

Re: Best 40 -60 x lens (infinity corrected) on fullframe

Post by Scarodactyl »

Coaxial illumination is great for some subjects but I'd say they're the exception rather than the rule. Still, 1mm isn't too bad if your lights are sufficiently bright, you don't mind fiddling with them longer than usual, and you just need those extra fine details. Not what I'd call a daily driver objective, but a solid 'nice to have' addition to thr toolkit, and if you watch long enough a decent short wd objective of one sort or other can often be found surprisingly cheaply.

Chris S.
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Re: Best 40 -60 x lens (infinity corrected) on fullframe

Post by Chris S. »

Kurt24 wrote:
Sun May 16, 2021 7:55 am
I found the Mitutoyo M Plan APO 50x HR, which has an aperture of 0.75 and accordingly a t stop of 33. I can imaging, that this is fine. The free working distance is low (5-6 mm) but that should be doable with my lighting setup. But I couldn't find images or a test.
Kurt,

I once tested a Mitutoyo M Plan Apo HR 50/0.75 and considered it excellent. I'm just now uploading the test files to my dropbox, and will PM you a download link so that you can form your own opinion. You will get a zip file containing three TIFFs:

1 Mitutoyo 50/0.75
2 Mitutoyo 50/0.55
3 Mitutoyo 100/0.70

The test target was, fittingly enough, a wing scale from a sunset moth--not one of the curved, shiny scales for which this moth is famous, but a flat, black one with features around the resolution limits for these objectives.

The camera body was not full frame (a Nikon D7100 with an APS-C sensor), so I can't speak to this objective's coverage on 24x36mm. This said, my guess would be that it would work quite well.

The other two objectives that I compared the HR lens with are my own, and I've tested each of these against multiple other objectives of the same type. So I'm confident that they provide dependable comparisons against which to judge the HR.

Since I was impressed with the 50/0.75 HR, and had some time before sending on to its owner, I tried using it to photograph the pits of a brown marmorated stink bug. Here, the lens was disappointing. Given the large, flat front of the lens, and the somewhat shallow working distance, incident light was restricted to shallow, glancing angles. This did two things: accentuate the surface texture of the bug and leave the bottoms of the bug's pits in deep shadow. The accentuated surface texture is neither good nor bad, depending on what one wants; but seeing this did make be realized that with this objective, I would not have the freedom to light such a bug otherwise if I wanted a different effect. Having the pits in deep shadow, however, was a problem, as it was features at the bottom of these pits that I wanted to document.

For butterfly wings, I think the 50x HR will mostly be fine. Exceptions might be found if you encounter shiny scales with pits, and desire a particular look that requires higher angle lighting.

--Chris S.

Kurt24
Posts: 4
Joined: Thu Feb 25, 2016 4:20 am
Location: Germany

Re: Best 40 -60 x lens (infinity corrected) on fullframe

Post by Kurt24 »

Dear all,
thanks very much for the feedback!
The resolution of the Mitu 50 x HR looks much better than the usual M Plan 50x!

If anybody has this lens and is using it on fullframe a comment is highly welcome!!!
I'll try to check with Mitutoyo Europe, whether they have a 50x HR for testing purposes available. If I can get my hands on one, I'll post example images.

ADi,
both names are fine :) I just encountered that one of my first names is hard to pronounce outside northern Europe.

Cheers,
Kurt
Best regars,

Kurt

Beatsy
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Re: Best 40 -60 x lens (infinity corrected) on fullframe

Post by Beatsy »

Kurt24 wrote:
Tue May 18, 2021 1:24 am
...I'll try to check with Mitutoyo Europe, whether they have a 50x HR for testing purposes available. If I can get my hands on one, I'll post example images.
Ooh, I hope they lend you one, I'm very interested in the outcome. Fingers crossed.

The 50x can be well into empty mag at N.A. 0.55 (compared to the lower power Mitties) depending on the tube lens FL and sensor pitch, of course. But it certainly is if you're covering a hi-res, full-frame sensor. That got me thinking about that HR version too - for the same reasons. Painful price - but if it were blessed by someone with similar uses to mine... Well. I might have to give up a future camera upgrade, or two, and buy one myself.

I know I'd be happy with the resolution (0.3 micron at NA 0.75), but working distance is a big worry. Practically a show-stopper for me. I put a bit of cardboard around my normal Mitty 50x, extending the outer barrel to simulate the working distance of the HR version. That big fat front end makes 5.2mm working distance feel like 2.5mm - or less!! You can squeeze light in there, but options for "nice lighting" are very restricted. I didn't think I'd like it in practice and stopped thinking about the lens. Until now. Curses... :roll: :D

Scarodactyl
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Re: Best 40 -60 x lens (infinity corrected) on fullframe

Post by Scarodactyl »

There are a couple weird Chinese no name NIR plan apo 50xes that have intriguing specs, either 50x/0.65 with 9.6mm working distance or 50x/0.8 with 4mm (plus, unfortunately, correction for 0.7mm of cover glass) and a 50x/0.7 NUV apparently from the same maker with 3.5mm wd. But of course they're still very expensive, there's no way they have good coverage and even center performance is going to be suspect, but if I ever found one cheap I'd definitely give it a try.

patta
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Re: Best 40 -60 x lens (infinity corrected) on fullframe

Post by patta »

There is/was a stream of used surplus Nikon planapo 20x 0.75, very convenient price, may fit for some use.
Yes it is only 20x, but that means very large available field, if you use a shorter tube lens. NA is the substantial 0.75. Massive "etendue" !

Working distance is nil, 1mm, but the nose is as narrow as possible and some illumination is doable. It is designed for use on microscope, with glass coverslip. Without, it has some aberration/haze; it gets ok when stopped down at NA 0.50 with a stop in the back, or at the tube lens.

Anyway, NA 0.75, can't leave much space for lateral illumination, the lens needs to be large and near.
If you're willing to go water/oil immersion, then yes, there are many, expensive objectives made for inverted microscope, with long working distance. They will still need some creativity to get the right illumination inside the liquid.

My two cents, this 20x is the best /only good lens I have. May you enjoy the Mitutoyos...
Last edited by patta on Mon May 24, 2021 4:00 am, edited 2 times in total.

Scarodactyl
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Joined: Sat Apr 14, 2018 10:26 am

Re: Best 40 -60 x lens (infinity corrected) on fullframe

Post by Scarodactyl »

The nikon 20x planapo is definitely a spectacular objective, insane for the price, and there has been some success attaching a cover slip to the front so you can use it as a metallurgical objective. I've found lighting with it surprisingly workable, though I've only used it for imaging inclusions within transparent minerals and that lets me cheat on lighting angles a bit.
I don't know if the 100 dollar guy has more or not. He puts them up irregularly, though they get bought up a lot faster now, presumably by other dealers.

adamski
Posts: 39
Joined: Fri Oct 21, 2016 11:36 am

Re: Best 40 -60 x lens (infinity corrected) on fullframe

Post by adamski »

Hi!
I have mity 50x HR which I am planning to sale, I would be happy to send it for testing if you are happy to cover the postage both ways? Please let me know, thanks.

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