Image sharpness problem - Mitutoyo 10x and 20x

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pu5z3k
Posts: 62
Joined: Sat Apr 23, 2011 5:48 am
Location: poland

Image sharpness problem - Mitutoyo 10x and 20x

Post by pu5z3k »

Hello all,
I have been struggling with the problem of low image quality for a very long time - basically the lack of sharpness when using 10x and 20x (mitutoyo) lenses

As a Tube Lens I use 40-150 2.8 PRO + two intermediate rings to reduce vinification.

with mitutoyo 5x it works great - which is confirmed by the photo below:
Imagemitutoyo 5x by Radoslaw, on Flickr

however, the matter changes dramatically, after connecting, for example, mitutoyo 10x or 20x, there is no question of any micrometer where the area is sharp.
It looks as if the image area is not completely in focus ...

I figured the tube lens might be the problem, so I bought a 70-300 lens to have the required 200mm focal length - unfortunately the problem is the same.

here are photos from 10x mitutoyo:
Imagemitutoyo 10x by Radoslaw, on Flickr

and 20x mitutoyo
ImageMitutoyo 20x by Radoslaw, on Flickr


My setup looks like that:
Image20220701_230830 by Radoslaw, on Flickr

Image20220608_061110 by Radoslaw, on Flickr


The exact specification of the set is:
Olympus OM-1 + 2 adapter rings (approx. 20mm) + 40-150 2.8 PRO

The lenses are attached with an adapter (which has been flocked out)

I wonder if, for example, the reason for the lack of focus is the need to keep some distance between the front element of the objective (tube lens) and the microscope objective.

My second theory, is there too much F-stop number due to the use of such a lens and in a set with e.g. mitutoyo 10x


I am begging you for help, I am already powerless in this matter.

Kind regards,

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Adalbert
Posts: 2426
Joined: Mon Nov 30, 2015 1:09 pm

Re: Image sharpness problem - Mitutoyo 10x and 20x

Post by Adalbert »

Hi Radek,
Well, the photo taken with the Mitu-10 looks great.
Could you please give the full name and parameters of your Mitu-20x (it looks like NIR)?
Best, ADi
Last edited by Adalbert on Wed Jul 06, 2022 8:46 am, edited 1 time in total.

Scarodactyl
Posts: 1617
Joined: Sat Apr 14, 2018 10:26 am

Re: Image sharpness problem - Mitutoyo 10x and 20x

Post by Scarodactyl »

First, that is an NIR LCD Plan Apo 20x, not an M Plan Apo 20x. Where did you even get that. The LCD specification means it expects some cover glass between it and its subject (of 0.7mm in this case). If you want to swap for a normal mitutoyo m plan apo 20x I have one in surplus and have wanted to try the LCD variation. That said I am not sure what the relative value is on the used market--new they cost more than a normal m plan apo but there is less demand for used copies. Point being you might also have some luck selling it and buying a normal 20x. Without the cover glass you'll get spherical aberrations which will affect contrast.

pu5z3k
Posts: 62
Joined: Sat Apr 23, 2011 5:48 am
Location: poland

Re: Image sharpness problem - Mitutoyo 10x and 20x

Post by pu5z3k »

that i didint know - i was thought that the NIR working same like normal lens

well i pay almost 1k Euro for that - if u want we can trade if You are in Europe

Scarodactyl
Posts: 1617
Joined: Sat Apr 14, 2018 10:26 am

Re: Image sharpness problem - Mitutoyo 10x and 20x

Post by Scarodactyl »

I'm in the US which would be less ideal unfortunately. I'd still be game if you want to try but it might be easier for you to just resell it. The NIR part isn't necessarily a problem (though it might not be as well corrected in the visible range, not much testing done on these), but the cover glass correction will definitely cause trouble. My interest is because most of my subjects are inside gems so the correction can help me.

pu5z3k
Posts: 62
Joined: Sat Apr 23, 2011 5:48 am
Location: poland

Re: Image sharpness problem - Mitutoyo 10x and 20x

Post by pu5z3k »

so here is another testing of mitutoyo 10x
i was using two lenses
olympus 70-300
olympus 40-150 2.8 Pro

here are result:
1. 70-300 @ 200mm - full size
in my opinion sharpness is very poor
Image70-300-@200mm-mitu by Radoslaw, on Flickr

2.
same lens, same picture just 50% cropped
Image70-300-@200mm-50%-crop--mitu by Radoslaw, on Flickr

3.
here is 40-150 pro - full size
slightly better but still in my opinion not as good i was observe picture from other people
Image40-150-pro-mitu-fs by Radoslaw, on Flickr

4.
same picture but cropped
Image40-150-pro-70%-croap by Radoslaw, on Flickr



Any idea what i should check ?

rjlittlefield
Site Admin
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Location: Richland, Washington State, USA
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Re: Image sharpness problem - Mitutoyo 10x and 20x

Post by rjlittlefield »

A difference in sharpness between 5X and 10X will not be due to the tube lens. Both objectives make the same demands on the tube lens, and will run at the same effective aperture.

The 10X objective will be twice as sensitive to any vibration in the system, but your images do not look to me like they are softened by motion blurring.

That leaves a difference between the objectives.

One painful possibility is that the 10X objective has been slightly damaged, so that its lens elements are no longer perfectly aligned. This is quite common with used Mitutoyo objectives. See for example my story at https://www.photomacrography.net/forum/ ... hp?t=20594 .

As a practical matter, Mitutoyo M Plan Apo objectives cannot be repaired; the tolerances are very tight and even Mitutoyo cannot be paid enough to fix them.

If the objective is damaged in this way, then the practical choice is between living with the softness or replacing the objective. For the sample images that you have posted, significant improvement can be made by digital sharpening.

--Rik

Scarodactyl
Posts: 1617
Joined: Sat Apr 14, 2018 10:26 am

Re: Image sharpness problem - Mitutoyo 10x and 20x

Post by Scarodactyl »

There's one factor that the 5x wouldn't mind but the 10x might, which is whether your tube lens is focused at infinity. Did you say you had two intermediate rings?

pu5z3k
Posts: 62
Joined: Sat Apr 23, 2011 5:48 am
Location: poland

Re: Image sharpness problem - Mitutoyo 10x and 20x

Post by pu5z3k »

yes i was adding two extension tubes between body and lens, to reduce vignetting

JKT
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Re: Image sharpness problem - Mitutoyo 10x and 20x

Post by JKT »

pu5z3k wrote:
Thu Jul 07, 2022 11:21 pm
yes i was adding two extension tubes between body and lens, to reduce vignetting
You could try 10x without the extensions for testing purposes. If the center is then sharp, you know the problem. And if that is the problem, the 20x will be hit even worse regardless of the version.

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