Telling a bad second-hand Mitutoyo from a good one

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Barrelcactusaddict
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Telling a bad second-hand Mitutoyo from a good one

Post by Barrelcactusaddict »

Administrator's note: This topic has been split off from How good are alternatives (clones) to Mitutoyo lenses--AdminCS
mjkzz wrote:
Sat Oct 16, 2021 4:43 pm
ah, I wrote this blog post in April 2017, that was at least a year later as some people was asking about it, so I wrote a general post on how to check CA. That means, I got the copy back in midlle of 2016, quite long time ago.

Note, in the blog, I used a 135mm lens for the QV and the "clone", 200mm for the 4X generic cheap objective.

https://pylin.com/2017/04/27/checking-m ... berration/
That's an excellent blog post, very informative! There aren't too many objective comparison-type posts out there, which is unfortunate.

If I end up getting a used Mitutoyo 5x objective, do you think I'd be safe in assuming it's been previously disassembled if it has noticeable CA when used with my 100mm and 200mm Pentax telephoto lenses? As a hobbyist, my budget is absolutely abysmal, so I can't possibly afford a new Mitutoyo, much less an additional used objective to compare it to; hopefully I'll find an honest seller.

mjkzz
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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by mjkzz »

Barrelcactusaddict wrote:
Sat Oct 16, 2021 6:05 pm
mjkzz wrote:
Sat Oct 16, 2021 4:43 pm
ah, I wrote this blog post in April 2017, that was at least a year later as some people was asking about it, so I wrote a general post on how to check CA. That means, I got the copy back in midlle of 2016, quite long time ago.

Note, in the blog, I used a 135mm lens for the QV and the "clone", 200mm for the 4X generic cheap objective.

https://pylin.com/2017/04/27/checking-m ... berration/
That's an excellent blog post, very informative! There aren't too many objective comparison-type posts out there, which is unfortunate.

If I end up getting a used Mitutoyo 5x objective, do you think I'd be safe in assuming it's been previously disassembled if it has noticeable CA when used with my 100mm and 200mm Pentax telephoto lenses? As a hobbyist, my budget is absolutely abysmal, so I can't possibly afford a new Mitutoyo, much less an additional used objective to compare it to; hopefully I'll find an honest seller.
Oh, I really do not know and I am really not very experienced in dealing with a lot of objectives.

Barrelcactusaddict
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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by Barrelcactusaddict »

mjkzz wrote:
Sat Oct 16, 2021 6:21 pm
Oh, I really do not know and I am really not very experienced in dealing with a lot of objectives.
That's okay, thank you though, no worries. You've certainly got far more experience than I have in dealing with microscope objectives; I do appreciate your having answered my previous questions, it was very helpful. :D

Barrelcactusaddict
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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by Barrelcactusaddict »

mjkzz wrote:
Sat Oct 16, 2021 6:24 pm
yes, there are a lot of scratches on the real mitty, some are severe to be classified as ding that looks like it ran into some sharp object. I got that one from a factory automation auction and you know how it is in a factory, and it has been dropped a few time by me, yet it still performs well in my opinion
Hm, that is actually very reassuring to me to hear that a genuine Mitutoyo holds up so well! I probably shouldn't worry so much, when it comes to looking for a used Mitutoyo. :)

I think I place too much stress on worrying about blemishes to the lens of objectives, and regular camera lenses as well; perhaps it may be a bit of a bad habit of mine.

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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by Chris S. »

Barrelcactusaddict wrote:
Sat Oct 16, 2021 6:05 pm
If I end up getting a used Mitutoyo 5x objective, do you think I'd be safe in assuming it's been previously disassembled if it has noticeable CA when used with my 100mm and 200mm Pentax telephoto lenses? As a hobbyist, my budget is absolutely abysmal, so I can't possibly afford a new Mitutoyo, much less an additional used objective to compare it to; hopefully I'll find an honest seller.
It's very chancy to buy a used Mitutoyo objective unless you have a return period and the ability to test the objective within that period. A huge fraction of second-hand Mitutoyo objectives are bad, even if they have never been disassembled; perhaps they have only been bumped, which can ruin them forever. Further, CA is not the most common problem--more likely issues are more subtle and difficult to recognize without a strict comparison with a known-good specimen.

Also, one can't rely on an "honest" seller, as many apparently well-intentioned sellers don't seem to know when they have a bad specimen. Testing an objective takes time, equipment, and experience that sellers of inexpensive objectives rarely have. In fact, if a seller could provide such testing, his or her offerings would probably sell for higher prices. So what you need to find is some idiot who is willing and able to test a prospective lens for you. As you are in the US, that idiot is probably me. I have a set of known-good Mitutoyo objectives, and have tested them against many other specimens for forum members.

So when you find a used objective you are interested in buying, PM me to see if I have time to test it for you within the return window. (I may not have time just then, as I sometimes travel or may be busy just then.) If it works for both of us, consider having the objective shipped straight to me from the seller, which preserves more of the return window.

A few rules of thumb: My sense is that 5x objectives are less likely to be bad than higher-magnification objectives--though I'm not sure I have enough data points to assert this with confidence. As you are in the US, you should prefer objectives from US sellers; with sellers in China, South Korea and other nations in the Far East, the percentage of bad objectives has seemed higher, and shipping costs--to you, and especially from you if you need to return a bad lens--can be prohibitively high. (Yes, I do see that most of the 5x Mitties on eBay at present are from sellers in just such nations.) Don't worry much about the cosmetic quality of the objective--perfect looking objectives can produce optical crap, and ugly objectives can be optically stellar; this said, be aware that cosmetic issues should lower the price.

Also, if you can stretch your budget to purchase a "new" 5x Mitutoyo objective from Lightglass Optics (currently $420 USD), we have several reports from forum members that these specimens do indeed perform as new. In this singular case, you might not need to have the optic tested. In my experience, Lightglass Optics is a perfectly honest dealer. If they say an objective is new, it likely is. On the other hand, I've tested used objectives sold by them, and returned one or two. I think Lightglass sold them in good faith, not finding the issues on their own that I found; they definitely accepted the returns and provided refunds with zero issues.

--Chris S.

RobertOToole
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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by RobertOToole »

Chris S. wrote:
Sat Oct 16, 2021 9:14 pm
........5x Mitutoyo objective from Lightglass Optics (currently $420 USD), we have several reports from forum members that these specimens do indeed perform as new. ......
--Chris S.
Just sent BarrelCactus the same info Chris, you beat me too it.

LG is A-okay in my experience, I've sent at least 5 people and the purchase went through without any issues. At one point LG had something like 250 of the 5x M Plans all new in the box.

Best,

Robert

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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by Barrelcactusaddict »

Chris S. wrote:
Sat Oct 16, 2021 9:14 pm
Barrelcactusaddict wrote:
Sat Oct 16, 2021 6:05 pm
If I end up getting a used Mitutoyo 5x objective, do you think I'd be safe in assuming it's been previously disassembled if it has noticeable CA when used with my 100mm and 200mm Pentax telephoto lenses? As a hobbyist, my budget is absolutely abysmal, so I can't possibly afford a new Mitutoyo, much less an additional used objective to compare it to; hopefully I'll find an honest seller.
It's very chancy to buy a used Mitutoyo objective unless you have a return period and the ability to test the objective within that period. A huge fraction of second-hand Mitutoyo objectives are bad, even if they have never been disassembled; perhaps they have only been bumped, which can ruin them forever. Further, CA is not the most common problem--more likely issues are more subtle and difficult to recognize without a strict comparison with a known-good specimen.

Also, one can't rely on an "honest" seller, as many apparently well-intentioned sellers don't seem to know when they have a bad specimen. Testing an objective takes time, equipment, and experience that sellers of inexpensive objectives rarely have. In fact, if a seller could provide such testing, his or her offerings would probably sell for higher prices. So what you need to find is some idiot who is willing and able to test a prospective lens for you. As you are in the US, that idiot is probably me. I have a set of known-good Mitutoyo objectives, and have tested them against many other specimens for forum members.

So when you find a used objective you are interested in buying, PM me to see if I have time to test it for you within the return window. (I may not have time just then, as I sometimes travel or may be busy just then.) If it works for both of us, consider having the objective shipped straight to me from the seller, which preserves more of the return window.

A few rules of thumb: My sense is that 5x objectives are less likely to be bad than higher-magnification objectives--though I'm not sure I have enough data points to assert this with confidence. As you are in the US, you should prefer objectives from US sellers; with sellers in China, South Korea and other nations in the Far East, the percentage of bad objectives has seemed higher, and shipping costs--to you, and especially from you if you need to return a bad lens--can be prohibitively high. (Yes, I do see that most of the 5x Mitties on eBay at present are from sellers in just such nations.) Don't worry much about the cosmetic quality of the objective--perfect looking objectives can produce optical crap, and ugly objectives can be optically stellar; this said, be aware that cosmetic issues should lower the price.

Also, if you can stretch your budget to purchase a "new" 5x Mitutoyo objective from Lightglass Optics (currently $420 USD), we have several reports from forum members that these specimens do indeed perform as new. In this singular case, you might not need to have the optic tested. In my experience, Lightglass Optics is a perfectly honest dealer. If they say an objective is new, it likely is. On the other hand, I've tested used objectives sold by them, and returned one or two. I think Lightglass sold them in good faith, not finding the issues on their own that I found; they definitely accepted the returns and provided refunds with zero issues.

--Chris S.
Hi! Thank you so much for the offer, Chris! Yeah, unfortunately there are only a handful of used Mitutoyo objectives on eBay right now that are in the US; not too many sellers offer returns, either. I'm beginning to think eBay isn't the way to go; I always feel uneasy when perusing the various listings, for some reason, in addition to remembering what others have shared (on other sites) about purchasing used objectives via eBay.

Actually, I messaged Edmund Optics the other day asking if they might have a used objective of some kind at a discounted price, but I'm not holding out too much hope for that. Also, I've wondered about Lightglass Optics, as I looked at their site in past months when I began my search, but I couldn't find any BBB reviews, and I thought it disconcerting that they mentioned their Customer Service availability is somewhat limited; since you and Robert recommend them, I'll definitely consider purchasing from them! I'd assume that as a major distributor, Edmund Optics' objectives are new, but at $720 for the 5x Mitutoyo, I wonder if they're used.

I really appreciate your offer to inspect a used objective I'll purchase; I don't think I'll go with eBay on this purchase, so it'll likely be from either LGO or EO. :) I intend to purchase an objective as the last portion of my setup, so it may be a little while down the road (I have yet to obtain a SMC Pentax-M 100mm f/2.8 lens, SWEBO LS-001 focus rail, Manfrotto Super Clamp, and LED lighting). I've already assembled a makeshift copy stand from a 3/4"x20"x27" wood board, rubber feet, 1/2" floor flange, and a 30"x1/2" steel pipe.
Last edited by Barrelcactusaddict on Sun Oct 17, 2021 6:39 pm, edited 1 time in total.

Barrelcactusaddict
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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by Barrelcactusaddict »

RobertOToole wrote:
Sun Oct 17, 2021 2:52 pm
Chris S. wrote:
Sat Oct 16, 2021 9:14 pm
........5x Mitutoyo objective from Lightglass Optics (currently $420 USD), we have several reports from forum members that these specimens do indeed perform as new. ......
--Chris S.
Just sent BarrelCactus the same info Chris, you beat me too it.

LG is A-okay in my experience, I've sent at least 5 people and the purchase went through without any issues. At one point LG had something like 250 of the 5x M Plans all new in the box.

Best,

Robert
Excellent, thank you so much for your recommendation, Robert! It's very reassuring to know that there are several others who have had good experiences in purchasing from them. :)

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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by mjkzz »

When an objective looks so bad cosmetically, and if it has dings on the front element, NOBODY wants it, and most seller do not even put it up on sale. I got that beat-up 5x for such low price, I can afford to just forget about it, just like the "clone". The reason I went for the mitty 5x is that I read a post here (I think Chris S. wrote it) about a 50x mitty and it performed so well even though it had a large ding on the front element.

Being so happy with experience, I even paid almost 800USD to get a 20x Mitty that is so good cosmetically, but it turned out to be a lemon, performed badly so I returned it. But even so, I only hunt for Mitutoyo objectives, not any other brand, this might sound narrow-minded, but to me it is safer.

Barrelcactusaddict
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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by Barrelcactusaddict »

mjkzz wrote:
Sun Oct 17, 2021 6:45 pm
When an objective looks so bad cosmetically, and if it has dings on the front element, NOBODY wants it, and most seller do not even put it up on sale. I got that beat-up 5x for such low price, I can afford to just forget about it, just like the "clone". The reason I went for the mitty 5x is that I read a post here (I think Chris S. wrote it) about a 50x mitty and it performed so well even though it had a large ding on the front element.

Being so happy with experience, I even paid almost 800USD to get a 20x Mitty that is so good cosmetically, but it turned out to be a lemon, performed badly so I returned it. But even so, I only hunt for Mitutoyo objectives, not any other brand, this might sound narrow-minded, but to me it is safer.
That's true, I suppose a major distributor like Edmund Optics probably wouldn't carry superficially-damaged objectives. I'm guessing that all of their products are unused and direct from the manufacturer. I don't think it's a bad idea at all to keep an open mind, though when it comes to major purchases, sticking with a renowned brand (or one with which one has had excellent experiences) is arguably the best course.

I'm a little curious, was that 20x Mitutoyo you purchased from a distributor?

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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by mjkzz »

No, the 20x was not from distributor, it was from a seller on Taobao (China domestic version of AliExpress), it looks great, but pretty bad in performance.

Yes, stick with distributors, too, but I doubt these distributors sell "used" ones

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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by Barrelcactusaddict »

mjkzz wrote:
Sun Oct 17, 2021 7:23 pm
No, the 20x was not from distributor, it was from a seller on Taobao (China domestic version of AliExpress), it looks great, but pretty bad in performance.

Yes, stick with distributors, too, but I doubt these distributors sell "used" ones
Ah, okay, well I'm glad you were able to return it!

By "performance" you mean chromatic aberration? I'm curious to know if that's the main thing to look for when spotting optical issues with microscope objectives (or at least, the most important).

Yeah, I think I'm going to have to go with a distributor; I don't see too many promising listings on eBay, and I've never felt comfortable when considering those listings. :lol:

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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by Scarodactyl »

I've had decent luck on eBay, though I've returned a few lemons.

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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by Barrelcactusaddict »

Scarodactyl wrote:
Sun Oct 17, 2021 7:46 pm
I've had decent luck on eBay, though I've returned a few lemons.
Were those mostly issues with chromatic aberration? I'd love to know what issues would be of most significance to look out for when inspecting the performance of an objective.

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Re: How good are alternatives (clones) to Mitutoyo lenses

Post by rjlittlefield »

Barrelcactusaddict wrote:
Sun Oct 17, 2021 7:52 pm
Were those mostly issues with chromatic aberration? I'd love to know what issues would be of most significance to look out for when inspecting the performance of an objective.
The usual complaints that I see reported for used objectives are not CA, but lack of sharpness and related aberrations, often due to decentering.

See viewtopic.php?t=20594 for my one personal experience.

--Rik

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