Leica z 4x/0.234 HR macroscope objective vs mitutoyo 5x apo

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

Leica z 4x/0.234 HR macroscope objective vs mitutoyo 5x apo

Post by Scarodactyl »

I've been wanting to test this for a while--mounting a 2x objective from a Leica Z6 zoom macroscope onto a compound microscope and seeing how it does when used as an HR 4x objective. As with the Nikon AZ100 objectives these have apparently high NAs for their nominal magnification, but would be significantly stopped down at lower magnifications by their zoom body and are nominally specced for small field numbers. But while the AZ100 objectives have gotten mixed results, I saw the Leica objective as having two promising qualities: one, its generally better specs and ability to cover aps-C (well enough anyway) when mounted on the Z6, and two, the fact that I already own one. All I needed was an adapter, which came in today.
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Where the 2x should be mounted (currently using the 0.5x to look at weird fuzz on an opal, more on that later).
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Where it is mounted currently. The 2x is almost parfocal with 95mm objectives, sitting maybe 1mm too high with the adapter. It's technically within shimming range. The Z6 with the 2x objective is supposed to top out at an NA of 0.234 when fully zoomed in which should be a lower bound when the objective is mounted directly on a tube lens. The reference FL of the Z6 system is 100mm so it gives 4x when mounted on a Nikon 200mm tube lens. Its working distance is even longer than a normal Mitutoyo 5x, making up for thr dumb flange on the end of thr objective.
To the eye it gives a very crisp image but it is not very planar, similar to the Thorlabs 2x or Optem 2.5x. It does take a fair bit of extra stacking on flat subjects like a wafer.
Anyway here are the 100% crops. As usual these are shot on my Nikon frankenscope using a Nikon optiphot head's tube lens (itl200 or equivalent) and my Canon T7 24mp aps-c camera, lit with coaxial illumination. The mitutoyo 5x shot is downsized to match the 4x magnification of the Leica objective.
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I started with a center detail shot of some busy area of the wafer. They're both good as expected, and the Leica is definitely sharper and has better contrast. I would probably need a higher resolution sensor to really see the difference here.
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I shot some letters in the corner of each lens's image and suss out CA. There isn't much visible on either but the subject is probably not great for this.
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I also put some of this detailed area in the corner of each sensor. The Leica seems to give better detail, and even though it needs more stacking in the corner the final result is very good.
Overall I think this would need better testing to establish how good it really is and how it would hold up to serious HR objective options like the Mitutoyo 5x HR or even the Mag.x--almost certainly not as good, but who knows? The Leica 2x is something like half as much as a Mitutoyo HR when bought new.
It would be less convenient than the mitutoyo for my usage because of the lack of planarity and poor performance with my DIC prism, but mechanically it is surprisingly problem free and has good working distance too. It's definitely giving a better final image, but I'm not sure it looks as much brighter than the mitutoyo 5x than I'd expect.
Last edited by Scarodactyl on Sun Mar 26, 2023 8:12 pm, edited 5 times in total.

RobertOToole
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Re: Leica z 4x/0.234 HR macroscope objective vs mitutoyo 5x apo

Post by RobertOToole »

I've been waiting for someone to do something like this with a Z6 lens for awhile. Results are better than I expected, thanks for posting this. I always wondered about these since I see them for sale from time to time. Specs look great especially the NA of the lenses. I had a AZ100 4x and gave up after a few tries (in 2017 maybe?). #-o

Best,

Robert

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

Re: Leica z 4x/0.234 HR macroscope objective vs mitutoyo 5x apo

Post by Scarodactyl »

It certainly makes the Leica 5x/0.5 more appealing if one were ever to appear for sale at a decent price.
I'll probably do some more tests on different subjects. Need to figure out how to coax out CA better, I can see a hint but it isn't that obvious. I probably need to get some better wafers.

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