What type of lens might stand in for stereo (CMO) objective?

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Scarodactyl
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What type of lens might stand in for stereo (CMO) objective?

Post by Scarodactyl »

I recently got my hands on a relatively inexpensive Leica Z16 macroscope zoom body, which I am hoping to put on my Wild M420 macroscope to replace the makrozoom lens (both for the impressive zoom range and because the makrozoom produces occasionally distracting axial ca). I got the coupler to connect the z16 and m420 head directly from leica for a decent price--it has no optics, just a mechanical coupling, suggesting they really are closely related systems.

Here's the rub: the z16 I bought didn't come with an objective, and as far as I can tell it won't focus without one. I found it would make an image when I held a b&l sz 2x aux lens in front of it (distorted but in focus) Though it is not itself a stereo setup, the Z16 uses the same objectives as their later MZ series stereo scopes.

Simply put, Leica apo stereo objectives are expensive, typically costing more than I paid for the zoom body. If I have to I'll go there, but I have been wondering if I might be able to use something else. Leica does provide couplers to put on other optics like optem or mitutoyo objectives which seem to adapt directly, not over another objective, so I kind of wonder if I could slap on a different 1xish apo lens and get a good (and much cheaper) result. My m420 head is already attached to an olympus base and focus mount with a wooden adapter so I'm certainly happy to further the frankenscope aesthetic if it is workable. If so, what kind of lens is most likely to work? I have already ordered a 1x CMO off an ao cycloptic because it is cheap, allegedly apo and it would be hilarious if it worked. I am wondering if one of the nice film scanner lenses would also be a good target, or if there is something else I am overlooking.

The next challenge will be figuring out how to control, replace or remove the motors, because guess who bought the motorized version of the z16 without the controller (it's me). This may end up being a nightmare project overall but at least it will keep me occupied.

enricosavazzi
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Re: What type of lens might stand in for stereo (CMO) object

Post by enricosavazzi »

Scarodactyl wrote:[...]
The next challenge will be figuring out how to control, replace or remove the motors, because guess who bought the motorized version of the z16 without the controller (it's me). This may end up being a nightmare project overall but at least it will keep me occupied.
For manual operation, removing the motors is probably the only (and simplest) solution. I have no specific information, but in these cases the zoom body is typically internally the same or very similar in the manual and motorized versions. Most of the required modifications in these cases are to expose the adjustment rings by cutting off portions of the external cover of the body.

If the motorized zoom ring has no markings, adding them will be necessary.

Reverse-engineering a dedicated motor controller interface is not a trivial task. The objective probably has optical or magnetic sensors to tell the controller where in the magnification range the objective is currently set. I don't know if there is also a variable aperture, but if so, it probably also has position sensors. An off-the-shelf simple motor controller knows nothing of these things, so it needs to be supervised by a microcomputer board like an Arduino or RasPi. Then you need to write the software. It can be done, but the final result will do nothing more than a manually operated zoom already does, so it may not be worth it. Finding a working dedicated Z16 controller is not easy either.
--ES

Scarodactyl
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Post by Scarodactyl »

Thanks for the tips! It's really good to hear there is basically a manual one hiding under that white shell. I had hoped that would be the case, and it seemed pretty likely, but I don't know enough about how these things are made to be sure (and it's more intimidating to unscrew anything on a system like this than a stereozoom or something like that.)
And yeah, getting a real co troller is nontrivial. It doesn't even seem to have its own part number so getting it from Leica is not easy.

Lou Jost
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Post by Lou Jost »

I have the opposite problem as you....I have Cycloptic 2x and Leica Apo 2x stereo objectives, and I am trying to figure out what other correction lenses or tube lens I need to make them work for macrophotography. If I can't figure it out, I can sell you one or both of those objectives....the stated resolution of this Leica lens is 900 lp/mm, which seems incredible for a 2x lens. So it seems worthwhile to figure it out.

Ichthyophthirius
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Post by Ichthyophthirius »

Hi,

I have also tried to find something that works as a replacement for CMO objectives. At the lowest zoom setting, simple converging lenses like the Raynox diopters give an image, but as soon as I zoom in, the image quality goes down and it becomes unusable.

During my search I found this seller https://www.oem-optical.com/CMO_replace ... Z_SPZ.html If you are in the US, this might be an option? I haven't tried it myself but if you do a test, please let us know :D

Regards, Ichty

Scarodactyl
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Post by Scarodactyl »

Lou Jost wrote:I have the opposite problem as you....I have Cycloptic 2x and Leica Apo 2x stereo objectives, and I am trying to figure out what other correction lenses or tube lens I need to make them work for macrophotography. If I can't figure it out, I can sell you one or both of those objectives....the stated resolution of this Leica lens is 900 lp/mm, which seems incredible for a 2x lens. So it seems worthwhile to figure it out.
Cool, maybe this will end up being a fun project with some interesting results, but if not I'll definitely be calling about that 2x.
@Ichthyophthirius Hmm, that's good to know anyway even if it's not great news. I guess a kitchen sink approach is probably called for. The linked seller seems interesting but their objectives are all planachro (aside from the 0.32x), and I think I could get a used planachro wild/leica one for a comparable price, or failing that a nikon or olympus or something. But we'll see. I guess I'll start with the cheapest possible options first and move up from there.


Edit: So, here's my list of things to try out so far:
1) primefilm scanner lens, to see if scanner lenses are an avenue to explore (on its way)
2) kenko closeup lens (I recently picked one up because of its very low cost and decent score on the tube lens test)(currently on my table)
3) whatever stereo auxiliary lenses I have, aside from the B&L sz 1-5 lens which works but sucks--I think I have a 2x from a B&L zoom 240 which won't likely be better and an AO 2x which likely won't be better.
4) a couple Zeiss 2x aux lenses I got for super cheap on eBay (on their way)
5) AO cycloptic 1x CMO (on its way)
6) anything else I have lying around I guess
7+: ordering more things.

Less exploratory but also viable options I'll also keep an eye out for are a Wild/Leica 1x achro if I can find one cheaply, or any other brand planapo stereo objective.

The current delay is that the z16 is in China, because an attempted return ran up against the mighty Chinese tariffs so we worked out another deal, and it's eventually going to be sent back back (I hope!). Fortunately the seller was very cool and helpful about the whole thing and didn't take any opportunity to screw me over even when he could have.

Scarodactyl
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Post by Scarodactyl »

Sorry for the double post, just a quick update. I've been doing rough preliminary testing while I wait for the z16 to come back by holding lenses in front of my makrozoom objective and seeing how they do. This is a bad test because a) I can't take pictures while holding a lens under the m420 with my shaky hands so my opinions are really subjective and b) I tried each lens at varying subject:sensor distance ratios depending on what was easiest logistically

Of the ones I've tried so far:
A rodenstock omegaron 1:3,5 which I got from a film enlarger at a junk store. It seems to act as a slight enlarger. Vignettes at low zoom, soft at high zoom and it only seems to want to focus when held at some length from the makrozoom a few mm above the focus plane.
A vivitar 2x teleconverter, which seems to reduce mag a bit. It is reasonably sharp at high zoom but introduces noticeable lateral ca and vignettes at low zoom.
The cycloptic 1x CMO acts as an enlarger. It doesn't vignette at any mag, but does get soft at higher zoom, and has what looks to be slight axial CA.
The B&L 0.5x from the zoom 240 works surprisingly well at all zoom settings with no vignetting, but does introduce some lateral CA.
The primefilm scanner lens I just pulled out of a scanner has great performance at lower mag but of course vignettes, and suddenly loses contrast just before the 1.6x mark on the makrozoom. I'm not sure why that is.

Whether any of this will translate to the z16 where the front objective is a mandatory component rather than an add-on I am not sure.

Lou Jost
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Post by Lou Jost »

Well, I tried the Leica 2x PlanApo with various tube lenses. There is absolutely zero CA. But while the centers are nice, the edges have huge amounts of astigmatism and are soft. I am about to give up.....

Scarodactyl
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Post by Scarodactyl »

I just got another candidate in which has auditioned fairly well in front of my makrozoom lens: a 1x lens from a Wild camera adapter (I think a 'snoot lens' in techncial terms?):
Image
Image
It's a nicely-sized lens with a very obvious coating. Held with the square side against the end of the makrozoom lens it provides a slight magnfication with no vignetting at any zoom setting, and better doesn't seem to lose contrast or degrade the image or add noticeable CA at any mag. That said, the Makrozoom isn't that great to start with, and my hands still weren't totally stable holding it in place so subtler issues wouldn't be as visible, but this seems very promising.

That's odd about the Leica objective. It seems to me like stereo microscope objectives are in a weird position, somewhere between compound objectives and auxiliary lenses. I wonder if those issues wouldn't be visible on the appropriate scope, or if they're just considered acceptable on this kind of system?

I also picked up a normal planachro 1x stereo objective--I could have gotten a Nikon one for about 200-250, but I came across this entire Scienscope CMO stereo head with a plan 1x for 300: https://www.ebay.com/itm/SCIENSCOPE-E-S ... 663.l10137
Normally I wouldn't bother with a scienscope, but this one is about 4.5k new, and with a 1:10 zoom ratio and some weird ergonomic accessory that allegedly fits SMZ scopes as well I figured I had to give it a whirl, and it wouldn't be too hard to resell after testing it out and/or using the objective until I get an apo one. I'll probably make another thread for this one once it comes in and I get to try it out.

Lou Jost
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Post by Lou Jost »

I suspect there is an interaction between the objective and the zooming optics, which perhaps levels out the field curvature. Several people on this forum have noted similar problems with the Nikon AZ series stereo objectives. These are clearly incredible lenses and deliver stunning results when used as directed, they just aren't made for stand-alone photography. Looking through one of these with my eyes is an incredible experience. Wish I could capture what I see.

Scarodactyl
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Post by Scarodactyl »

OK! I finally got my Leica Z16 back in hand.
(I tried to return it, to China, and that didn't go well as you might guess. Live and learn!)
Anyway, I can finally test these collected lenses on it, and as an added bonus I got a damaged Leica planapo 1.6x lens (one of the many, many m series objectives) to test them against! It isn't one of the specifically speced for the z16 but it seems to work very well. Even holding it by hand against the end of the objective I can tell it's producing an image significantly better than the Makrozoom objective.
Note I can't really change the zoom setting right now, as I don't have the controller for the motors. That's the next project, either controlling the motors directly or adding knobs. So these results are at whatever zoom it is set to, which is relatively high.

So, quick results. For the sake of this post, "forward" means "the writing is right-side-up when held against the end of the lens", which might not be right but there you have it.
Leica 1.6x planapo (104726501)
Excellent view, extremely crisp and bright, no visible chromatic abberations. Very heavy lens. Working distance is relatively short, maybe 2.5cm, but should be fine for most purposes. Probably not using it in its intended configuration for WD but the results are very nice.

Bausch and Lomb Stereozoom 1-6 2x auxiliary lens: incredibly soft image, as you get it towards focus the colors get more vivid and you think something good will happen, but when you finally hit the focus plane it's a hazy mess. Surprising no one.

AO Cyclopic 1x apo CMO: surprisingly not that bad?? It drops off very quickly outside the focal plane, but inside it the field seems pretty flat and the colors look good. Pretty surprised at this, and I wonder how it might perform across different zoom ranges. Worth trying to properly adapt.

SMC Pentax 1:2 50mm lens by Asahi optical co: terrible results. Not
surprising.

Rodenstock Omegaron 1:3,5 f=50mm: produces a half decent image when reversed, but dim and kind of soft.

Canon 35-135mm ultrasonic: produces very soft image

Wild 1.0x MPS: showed promising results in tests as an auxiliary lens (ie, holding it in front of my makrozoom objective). It does produce an image when used here as a standalone that isn't actually that bad when forward (awful reversed), but the working distance is a foot and a half. I have no idea why that would be when it definitely did not do that to the makrozoom. Optical shenanigans I guess.

32mm tominion scanner lens: terrible performance forwards, functional backwards but the working distance is too short.

55mm tominon/noritsu scanner lens: better, longer working distance and slightly better performance. Seems to work better when held a little distance from the z16 zoom body. still, working distance is short for this setup.

80mm tominon/noritsu scanner lens: this one impresses me a bit. Good working distance, works best when held a little distance from the end of the zoom body, about the same forward and reversed. It produces what looks like a fairly crisp image, but it is maybe half as bright as the image produced by the leica planapo lens, which is interesting while producing a less magnified image. This one is worth figuring out a better mount for.

Topcon fm 4/32mm. Very short working distance, but works decently when reversed (terrible forward). Image is kind of dim.

damaged mitty 5x: works, fills entire frame at this magnification whatever that is. This one has etching on the glass so I can't tell how sharp the image is but it looks like it would be excellent otherwise. Leica actually sells an adapter to mount them on the z16 so that tracks.

Kenko closeup lens no. 5 (f=200): this one impressed me. Image looks fairly bright and good, maybe not quite as bright as the Leica but nice, at a working distance of just over 1 foot. If I need an ultra-long working distance option this would definitely be my pick over the Wild MPS. Best forward at a slight distance from the end of the z16.


Anyway, this test is incredibly preliminary but it helps me narrow down which ones to figure out how to mount so I can actually take photos for comparison, and whether they'll be good additions to the Leica lens.

Lou Jost
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Post by Lou Jost »

Interesting. I'm excited that the Leica 1.6x Planapo works for you. That means you have also solved the reverse problem-- how to use Leica stereo objective for photography; the optics in the rest of your system is what I need in order to be able to use my 2x Leica Planapo, which is a beautiful lens.....So what optics do you have in your set-up behind the Planapo? Can you show some results taken with your Planapo?

Congratulations and thanks in advance!!!

Scarodactyl
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Post by Scarodactyl »

No pictures yet unfortunately, I'll need to figure out how to adapt this objective to the zoom body. Just holding it by hand is too shaky, especially with such a heavy objective. As to the optics, I put it on a Leica zoom microscope, so basically into its intended usecase (though not 100% since the models are mismatched). No idea how it will do at other zoom factors. Controlling the zoom and fine focus motors are my next project.

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Post by Lou Jost »

Do you know what optics are in that zoom scope?

Scarodactyl
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Post by Scarodactyl »

Since I'll have to take the cover off again to work on the motors, I will take some pictures of what's inside and send them to you. Something heavily engineered anyway.

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