Lightglass Optics’ customer service is fine. It appears to me that the outfit is a one-man show, and likely that man’s sideline business. He will get back to you and treat you fairly, but it’s not a big-time operation where operators are standing by. The upside of this is that his overhead is likely low, and his prices reflect it.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;
Edmund Optics is a first-class, Tiffany-level provider of optics and related items. If they ever sell items that are not new—I don’t know if they do—you can be assured that this will be clearly disclosed in the offering. They do have customer service engineers standing by, who are very knowledgeable and helpful. Their prices, unsurprisingly, are not in the bargain region. I’ve purchased quite a few items from Edmund Optics, and spoken with support engineers—it’s an excellent source when your use case warrants.
Also consider Thorlabs, which, like Edmund Optics, is an excellent, full-service supplier of optics and other scientific items. They also have very good support engineers, and in many cases, their prices are a bit lower than Edmund Optics (although their house-brand opto-mechanical items are also a bit less jewel-like than EO). Just now, some of EO’s Mitutoyo objectives are priced a bit lower than Thorlabs, but this has not always been the case, and may not be in the future.
Lightglass Optics is normally a seller of second-hand items. How he acquired a large number of apparently new 5x objectives would be an interesting story. Edmund Optics and Thorlabs are, I’m pretty sure, both official Mitutoyo vendors.
Like Scarodactyl, I wouldn’t despise eBay as a place to find a nice Mitutoyo objective at a bargain price. I’ve tested many Mitutoyo objectives for forum members, the majority of them from eBay. Your odds of getting a good specimen may be 40-60 percent. This is why it’s vital to have a return privilege and test the objective. But the upside is that you can save a lot of money.
The issues in a bad specimen are almost never chromatic aberration. It’s mostly a decrease in contrast, an increase in fuzziness in fine features of the test subject, or an unevenness in the sharpness of those features when comparing the corners and sides of the image. Less often, you may see highlights near the edges appear stretched or star-like. At this level of comparison, you will soon find that there are legitimate differences between any two lenses, even new ones of the same model from the same factory; they are like snowflakes, with no two alike. For example, one good specimen may have a touch more contrast but a little bit more false color than another good specimen. These lenses are hand assembled, and despite high standards of quality control, their many elements have a surprising degree of variability from one to another. Clearly, the artisans who build these objectives by hand make tradeoffs as they do so.Barrelcactusaddict wrote: ↑Sun Oct 17, 2021 7:52 pmWere 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.
To test an objective to see if it is a good or bad specimen, here is what I think one needs to do: Compare a stacked-focus image taken with the unknown lens against exactly the same image taken with a known-good lens. Nothing should be changed between these images, other than the objective lens; the manner of lighting and the subject position must be exactly identical. The test rig should be very solid and capable repeatable results. The test subject should be chosen for having detail around the resolution limit for the objective in question. The lighting should be such that the entire aperture of the objective is utilized. The stacks should be done such that the tester “focuses through” the test subject, to include images in front of and in back of the test target, to minimize potential for focus error and influence of field curvature (which is a concern in traditional microscopy, but isn’t of much importance to focus-stackers).
Then layer the two images in Photoshop. Align them in Photoshop so that the views are perfectly overlapping, or as near to perfectly overlapping as possible. (This is needed because most objectives project somewhat differently onto the sensor—higher, lower, left or right; it may still not be perfect because objectives commonly magnify slightly above or below their rated magnification.) Then the tester begins a process of “flashing” the upper layer on and off, to permit careful, repeated comparison of images made by the two objectives. Zoom in, during this process, and pixel-peep.
See why I said you need “some idiot” to do it for you?
Or why I don’t think it practical for discount sellers of used objectives to routinely do it?--Chris S.
PS: Lothar, I fear we are hijacking your interesting and useful thread. Perhaps we should split this topic?
You certainly haven't put your foot in anything. I was mainly razzing Rik.
).