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Info On LMPLFL10X Objective
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apt403



Joined: 06 May 2019
Posts: 37
Location: Yelm, WA

PostPosted: Tue May 14, 2019 6:17 pm    Post subject: Info On LMPLFL10X Objective Reply with quote

Another info request post - I swear, this is all building to a (hopefully) interesting imaging setup that will be worth looking at!

I was browsing eBay and came across this listing (if eBay links are off-limits, please remove. My apologies!):

Olympus LMPLFL10X

I shot Olympus an email and will post whatever response I get here. But in the mean time, does anyone have any ideas?

Regardless, I'll stick it on the end of a 200mm tube lens and update this thread w/ test images after I receive it.

I can't find any information using the numbers listed on the box, nor can I find any Olympus objective that looks similar. At best, the outer barrel w/ identifying markings has been removed (somehow, for some reason). At worst, it's a different objective in an Olympus box (not accusing the seller of knowing misrepresentation). I figure the risk was worth the potential reward though.

The front lens appears to be more or less on par, size wise, with other known LWD objectives, but I can't get a very good look at how many lens elements there are in the body. Total length appears to be different than the LMPLFLN objectives listed on the Olympus website.
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Chris S.
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PostPosted: Tue May 14, 2019 8:27 pm    Post subject: Re: Info On LMPLFL10X Objective Reply with quote

apt403 wrote:
. . . if eBay links are off-limits, please remove.

There is no problem with eBay links posted for informational purposes, such as you've done here. Blatant promotion would be a different matter, but we rarely have that issue here.

Interesting lens. It certainly does look as if the barrel has been removed. Sometimes this is done to get a bit more working distance, but for this lens, the WD is already so large that this seems unlikely. Another possibility is that someone has worked on the lens (not good). Or perhaps Olympus sells lenses like this for special-purpose integrations under some other entity's branding? Only the latter would qualify as "new," in my view.

From the seller's other offerings, it would appear that he or she knows the equipment pretty well. This said, if your testing indicates that this lens isn't as described, I'd send it back.

As you're likely aware, some Olympus objectives require compensating eyepieces for CA, while other Olympus objectives do not. I don't know which are which, but we have a few members who likely do know.

--Chris S.
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ray_parkhurst



Joined: 20 Nov 2010
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Location: Santa Clara, CA, USA

PostPosted: Tue May 14, 2019 9:40 pm    Post subject: Reply with quote

I'm anxious to see the images from this lens. I've been looking for one for a long time, guess my searches are broken. I believe it will be a real gem!
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apt403



Joined: 06 May 2019
Posts: 37
Location: Yelm, WA

PostPosted: Tue May 14, 2019 11:10 pm    Post subject: Reply with quote

Chris S. wrote:
apt403 wrote:
. . . if eBay links are off-limits, please remove.

There is no problem with eBay links posted for informational purposes, such as you've done here. Blatant promotion would be a different matter, but we rarely have that issue here.

... Sometimes this is done to get a bit more working distance, but for this lens, the WD is already so large that this seems unlikely.

Another possibility is that someone has worked on the lens (not good).

Or perhaps Olympus sells lenses like this for special-purpose integrations under some other entity's branding? Only the latter would qualify as "new," in my view.

From the seller's other offerings, it would appear that he or she knows the equipment pretty well. This said, if your testing indicates that this lens isn't as described, I'd send it back.

As you're likely aware, some Olympus objectives require compensating eyepieces for CA, while other Olympus objectives do not. I don't know which are which, but we have a few members who likely do know.

--Chris S.


Gotcha, thanks for the clarification!

Another thought I had - Definitely wouldn't be a good situation. I was reading about the alignment process for the long working distance Mit. objectives - micron level positioning axially AND radially? No thanks.

I like that possibility!

That is a good point - It was clearly marketed as a 'new, open box' item, a pretty stringent criteria to hit.

Ah, that's a point I was aware of, but didn't consider! Hmm.. Well, we'll see. I could probably track down a compensating eyepiece and add it to the optical train, somehow, if need be.

ray_parkhurst wrote:
I'm anxious to see the images from this lens. I've been looking for one for a long time, guess my searches are broken. I believe it will be a real gem!


Thanks for the positive thinking! It'll come to you! I doubt your searching is broken, it was just plain luck on my part. I had more or less the cost of this objective earmarked for a new 100x finite, was cruising eBay and decided to search for long distance working objectives on a whim. Saw it, Googled around for a few minutes, and hit buy.

For some of the subjects I'd like to stack and stitch, the required focus depth is so large I just don't think it's physically possible to accomplish with anything but a long working distance objective. If this works out, I'll have to get busy working on a camera mount for my CNC router - Going to try the rotation around the entrance pupil method w/ a lightweight rotary table to begin with.

It's unfortunate companies like Lens Rentals don't do microscopy gear - I'd be much more inclined to rent the objectives I want than... Oh, I dunno. Sell a kidney? For something like a Mitutoyo 100x NA .7 LWD Plan APO. Laughing
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apt403



Joined: 06 May 2019
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Location: Yelm, WA

PostPosted: Wed May 15, 2019 4:47 pm    Post subject: Reply with quote

Okay, just got off the phone w/ an Olympus rep - The LMPLFL10X is for all intents and purposes the same as their current LMPLFLN10X; A few years ago they iterated the part number without changing the product. He didn't know the specifics, but said there's a high likelihood that they changed one of the lens elements to lead free glass for ROHS compliance, necessitating a part number revision.

Also asked him about the lack of a lens barrel - His official stance as an Olympus rep is that you definitely shouldn't attempt it, but in some circumstances they've shipped them without barrels to OEMs w/ specific use cases that necessitated removal. So, the jury is still out on whether or not its been tampered w/ but it is at least possible that the lens is in good condition.

Should have it be the end of the week, early next week - Test shots incoming!
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Chris S.
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PostPosted: Wed May 15, 2019 10:25 pm    Post subject: Reply with quote

So very possibly, your lens was intended for an OEM application--the best possible reason for a missing barrel. In that case, sounds as if you scored a very nice bargain. Very Happy

Did you ask the rep if a compensating eyepiece is required? To my mind, adding one to the optical train would be inconvenient. (Though we used say this about adding a tube lens to permit use of infinite objectives in macro rigs--and now it's routine.)

apt403 wrote:
It's unfortunate companies like Lens Rentals don't do microscopy gear - I'd be much more inclined to rent the objectives I want than... Oh, I dunno. Sell a kidney? For something like a Mitutoyo 100x NA .7 LWD Plan APO. Laughing

This observation got me thinking. I happen to have a Mitutoyo 100/0.70 objective, and my first thought was that letting other photographers rent it when I'm not using it might be a good thing. But then I got to thinking about how sensitive Mitutoyo objectives are to being "dropped or bumped," as Mitutoyo puts it. I've never had an objective go bad in my hands, but have tested plenty of bad specimens that looked cosmetically perfect. Just how much of a drop or bump did it take to turn them bad? I have no idea.

But if one wished to rent out such an objective, it would be sensible to optically test it before and after the rental, and insist on replacement if quality deteriorated. I'm sure we can all imagine the mess that such a policy would entail. Perhaps this is part of why these objectives are not generally available for rent?

--Chris S.
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Pau
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PostPosted: Thu May 16, 2019 12:01 am    Post subject: Reply with quote

Chris S. wrote:
Did you ask the rep if a compensating eyepiece is required?

According to Olympus literature (STM6 microscopes brochure) the LMPLFL10X belongs to the UIS series and so it is an infinite corrected objective and doesn't need compensating eyepieces (or compensating tube lens)
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Pau


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Chris S.
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PostPosted: Thu May 16, 2019 12:14 am    Post subject: Reply with quote

Thanks for this information, Pau! So it appears even more strongly that apt403 has found a quality lens at a bargain price. Very Happy

--Chris S.
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dmillard



Joined: 24 Oct 2006
Posts: 567
Location: Austin, Texas

PostPosted: Thu May 16, 2019 5:08 am    Post subject: Re: Info On LMPLFL10X Objective Reply with quote

apt403 wrote:

Regardless, I'll stick it on the end of a 200mm tube lens and update this thread w/ test images after I receive it.
.


It's designed to be used with a 180mm tube lens (such as Olympus's UTLU), but will work fine with 200mm, albeit at 10/9 its nominal magnification, producing an 11.1x magnification.

I have one that I'm pleased with.
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apt403



Joined: 06 May 2019
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Location: Yelm, WA

PostPosted: Thu May 16, 2019 11:58 am    Post subject: Re: Info On LMPLFL10X Objective Reply with quote

Chris S. wrote:

... This observation got me thinking. I happen to have a Mitutoyo 100/0.70 objective, and my first thought was that letting other photographers rent it when I'm not using it might be a good thing. But then I got to thinking about how sensitive Mitutoyo objectives are to being "dropped or bumped," as Mitutoyo puts it. I've never had an objective go bad in my hands, but have tested plenty of bad specimens that looked cosmetically perfect. Just how much of a drop or bump did it take to turn them bad? I have no idea.

But if one wished to rent out such an objective, it would be sensible to optically test it before and after the rental, and insist on replacement if quality deteriorated. I'm sure we can all imagine the mess that such a policy would entail. Perhaps this is part of why these objectives are not generally available for rent?

--Chris S.


First of all: I'm envious Laughing Do you have any images w/ that objective posted here?

Just casually mulling it over in my head, it doesn't seem like too bad an enterprise for a well-heeled individual to undertake. The relative fragility of these pieces of glass compared to something like a Nikon 800mm f/5.6 prime is a big problem. Finding an insurance company willing to write a policy for such a business would be the obvious thing to do, but from what I remember of Lens Rental's terms, users are responsible for any repairs resulting from damages incurred. They've been around for a while now, so I imagine if they could have, they would have secured such an agreement.

I imagine to be profitable, one would also have to also focus on other specialized imaging gear that would be enticing to universities or small private firms - I know a few professors working for small colleges that would fight tooth and nail to convince the actuarial side of their institutions that renting one of the sub-$100k desktop SEMs for a few semesters would be a great idea.

Alternatively, a subscription or 'club' based profit model could work out well, from a financial standpoint - A small fee for access to a pool of objectives and other associated gear - Then the cost of potential damages could be defrayed by the contribution of all members.

Pau wrote:
Chris S. wrote:
Did you ask the rep if a compensating eyepiece is required?

According to Olympus literature (STM6 microscopes brochure) the LMPLFL10X belongs to the UIS series and so it is an infinite corrected objective and doesn't need compensating eyepieces (or compensating tube lens)


Thanks for that info! I hadn't come up with an answer myself, and did forget to ask the rep about eyepieces.

dmillard wrote:

It's designed to be used with a 180mm tube lens (such as Olympus's UTLU), but will work fine with 200mm, albeit at 10/9 its nominal magnification, producing an 11.1x magnification.


180mm? Okay, good to know. Contingent on good operation, I'll have to start researching an appropriate tube lens to use in conjunction w/ this objective - I've got some time set aside today to attempt to document the optical performance of the tube lens I'm planning on using, so I've got some baseline to refer to during testing of the objective.


Having some trouble finding an appropriate adapter for this objective - I took it for granted that I'd be able to find an RMS -> M55 (or similar) on short notice - In retrospect, it is a little bit of an esoteric item; Amazon Prime's got me spoiled for choice these days. Best solution I've come up with so far is to order a set of stepdown rings, and machine an adapter out of whatever plastic stock I've got kicking around the shop. The thought of grinding a single point threading tooth for the Whitworth threadform doesn't exactly fill me with joy, but I believe I'll have to bite the bullet and get 'er done.
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apt403



Joined: 06 May 2019
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Location: Yelm, WA

PostPosted: Wed May 22, 2019 2:37 pm    Post subject: Reply with quote

Quick update - received the objective, been playing with it over the past couple days. I can say with certainty that it's a long working distance, 10x objective. I don't have any other plan apos to compare it to, but the image quality is far beyond the best I could manage with the achromats I've got on hand.

Testing w/ the 100mm Tokina both with and without the 2x teleconverter as a tube lens (giving ~5.5x and ~11x mag) show good corner to corner coverage and sharpness. I had ideas about using a 70-300mm kit lens, but wide open at f/6.3 there's heavy vignetting, as should have been expected.

Ran a stack last night with the scale adjustment turned off in Zerene, and it actually turned out pretty well! Hopefully it's near enough to telecentric I can stack and stitch with linear translations. I've been pounding my head against the wall trying to figure out how to build a reliable setup for rotation around the entrance pupil - a non-trivial engineering exercise @ 10x mag, to be sure!
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rjlittlefield
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PostPosted: Wed May 22, 2019 3:22 pm    Post subject: Reply with quote

apt403 wrote:
Ran a stack last night with the scale adjustment turned off in Zerene, and it actually turned out pretty well! Hopefully it's near enough to telecentric I can stack and stitch with linear translations.

That's what I would expect with any 10X objective. The DOF is so shallow that there is no significant change in scale within the DOF slab for any objective that I've seen. If yours is different, please let us know!

BTW, I'm the fellow who wrote Zerene Stacker. My standard advice for setting alignment parameters at 10X and above is to turn off scale correction because it's more likely to cause harm than good. The difficulty is that the computational alignment process that does scale "correction" can easily be led astray by how features change appearance as they go into and out of focus, even if the optics themselves are perfectly telecentric. The result can be craziness like a supposed 30% change in scale from one end to the other, caused actually by migration of OOF blurs as focus changes.

--Rik
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apt403



Joined: 06 May 2019
Posts: 37
Location: Yelm, WA

PostPosted: Wed May 22, 2019 5:36 pm    Post subject: Reply with quote

rjlittlefield wrote:

That's what I would expect with any 10X objective. The DOF is so shallow that there is no significant change in scale within the DOF slab for any objective that I've seen. If yours is different, please let us know!

BTW, I'm the fellow who wrote Zerene Stacker. My standard advice for setting alignment parameters at 10X and above is to turn off scale correction because it's more likely to cause harm than good. The difficulty is that the computational alignment process that does scale "correction" can easily be led astray by how features change appearance as they go into and out of focus, even if the optics themselves are perfectly telecentric. The result can be craziness like a supposed 30% change in scale from one end to the other, caused actually by migration of OOF blurs as focus changes.

--Rik


Ah ha! I remember you mentioning something similar in a post you wrote about technique options for stack and stitch, which prompted me to try it this morning. I wasn't aware that it was a general rule to follow for high magnifications though. I'll certainly update this thread w/ whatever info seems useful for others - I've noticed in your previous posts you mention quantified scale changes in objectives - such as a "scale change of about 1 part in 15,000 with a step size of 10 microns" in reference to a Mit. 10x Plan APO (thread here). How do you go about getting those measurements?

And I thank you for the work you've put in, both with Zerene and the world of photomacrography in general! Your writing has cut about... I dunno, being conservative, 5 or 6 thousand hours off my learning curve? Very Happy I'm sure by the time I accomplish my long term goal ( stack and stitch images for very large, high DPI prints), that number will increase by a few factors.
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rjlittlefield
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PostPosted: Wed May 22, 2019 11:46 pm    Post subject: Reply with quote

Thanks for the feedback -- I'm always happy to hear that my musings have saved somebody some time.

Measurements like "scale change of about 1 part in 15,000 with a step size of 10 microns" are straightforward in concept. You just set up an appropriate target, take two pictures at 5 microns behind and in front of perfect focus (so 10 microns apart), align those in Zerene Stacker, and look at the reported Scale factor. If it's 1.000067 = 1+1/15000, there's the "1 part in 15,000".

There are a couple of points that make the process work better.

Most important, you want a nearly planar subject with crisp fine detail all over the frame, that does not appear to "wiggle around" as you change focus. For that I use a piece of paper from a black-and-white Xerox-type copy of a "gray" background pattern printed by an ink jet printer, glued to a glass slide to keep it flat, illuminated by well diffused light with a wide range of angles. The larger spots and tiny specks of fused black toner provide a great fine-scale pattern for the image matcher to work with.

Then, if your lens has curvature of field, pick a focus point that makes the periphery sharp and let the center go soft. Edges and corners are the parts that are most sensitive to scale change anyway.

It's best to run the test stopped down to the aperture that you'll be using for the real shoot. With some optics the entrance pupil changes position as you stop down, especially from wide open to stopped at all.

And finally, you might want to run a series of comparisons with different step sizes, say nominal focus plus versus minus 5 microns, plus versus minus 10 microns, and so on. Usually there'll be some variation in the measurements. Some of that will be just random noise, which will be particularly important when both the step size and change of scale are very small. When the step size becomes very large, so that the images become very blurred, then the accuracy will also suffer because it's hard to determine the alignment of very blurred images. Someplace in the middle, with a difference in focus that ranges from say half DOF to a few DOF, the numbers will be pretty consistent and those are the ones that best represent the optics.

--Rik
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mjkzz



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PostPosted: Thu May 23, 2019 6:14 pm    Post subject: Reply with quote

rjlittlefield wrote:
Thanks for the feedback -- I'm always happy to hear that my musings have saved somebody some time.

Measurements like "scale change of about 1 part in 15,000 with a step size of 10 microns" are straightforward in concept. You just set up an appropriate target, take two pictures at 5 microns behind and in front of perfect focus (so 10 microns apart), align those in Zerene Stacker, and look at the reported Scale factor. If it's 1.000067 = 1+1/15000, there's the "1 part in 15,000".

There are a couple of points that make the process work better.

Most important, you want a nearly planar subject with crisp fine detail all over the frame, that does not appear to "wiggle around" as you change focus. For that I use a piece of paper from a black-and-white Xerox-type copy of a "gray" background pattern printed by an ink jet printer, glued to a glass slide to keep it flat, illuminated by well diffused light with a wide range of angles. The larger spots and tiny specks of fused black toner provide a great fine-scale pattern for the image matcher to work with.

Then, if your lens has curvature of field, pick a focus point that makes the periphery sharp and let the center go soft. Edges and corners are the parts that are most sensitive to scale change anyway.

It's best to run the test stopped down to the aperture that you'll be using for the real shoot. With some optics the entrance pupil changes position as you stop down, especially from wide open to stopped at all.

And finally, you might want to run a series of comparisons with different step sizes, say nominal focus plus versus minus 5 microns, plus versus minus 10 microns, and so on. Usually there'll be some variation in the measurements. Some of that will be just random noise, which will be particularly important when both the step size and change of scale are very small. When the step size becomes very large, so that the images become very blurred, then the accuracy will also suffer because it's hard to determine the alignment of very blurred images. Someplace in the middle, with a difference in focus that ranges from say half DOF to a few DOF, the numbers will be pretty consistent and those are the ones that best represent the optics.

--Rik


I guess shooting 100s of images of some random subject and then take the average (by taking 1/(n-1)th power) would not be a good measure for telecentricity?
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