3M Objective on the 'Shed

[ray_parkhurst]

Surplus Shed has 3M 18.25x "conical" objectives on sale for $8. I'm a fan of this series of objectives, and even had Raf make an adapter to convert them to M52 female for use with M52 reverse adapters. These have pretty wide coverage, easily covering FF at 6x and higher. Sharpness is pretty decent, but LoCAs are visible. I have used these for coins at 5x on APS-C or 7.5x on FF for the "money shot" on the Lincoln Cent, which shows the Date and Mintmark, see image below. Shot with A7Rm4.

The objective is also a superb 18x loupe with wide FOV for such high power.

Link to objective on SS: https://www.surplusshed.com/pages/item/L14923.html

The Money Shot

Center

Corner

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Edited to add: here is a 3D rendering of the Money Shot stack. The objective has flat field and low distortion. I expect it could be used for stitching as well.

[RobertOToole]

You beat me Ray how funny. I was going to post this a couple of weeks ago but I got side-tracked.

I wasn't sure if the 18x was a good one, I thought the lower mags were better, so glad to read the your post.


Robert

[ray_parkhurst]

I wasn't sure if the 18x was a good one, I thought the lower mags were better, so glad to read the your post.

I have examples of most of the mag range for these objectives, plus a bunch of other 3M objectives (including a few I got from you), and the 18.25x is one of the best. Strange this particular one showed up in surplus quantities.

[Scarodactyl]

Thanks! Ordered a couple, will see what I can do with them.

[simplejoy]

Thanks for the tip - they are indeed interesting lenses. I have one marked 3M 20.87X. It's pretty good, but I've only used it a couple of times and just once close to that magnification (20:1), where I was way out of my depth to be honest...

I had a conversation with a fellow macro-shooter some time ago who used a couple of those as well and while researching we found some hints towards the possibility that Olympus is the manufacturer of these. If memory serves me right there are even identically looking ones with Olympus inscriptions on them. Do you know more about that?

Here are some of the results with the 20.87X lens on full frame:

Hothead brought back to earth by simple.joy, on Flickr

Log-in by simple.joy, on Flickr

...both between 7:1 and 10:1 and here is the 20:1 attempt of my (aging) hair:

Hairitage by simple.joy, on Flickr

[ray_parkhurst]

Yes, many of the ones I have are marked Olympus. Some seem to be intended for Olympus equipment, and some for 3M. Also have some that look more like regular objectives, but the threading is smaller than RMS. They are for a different OEM company, can't remember which one, but also marked Olympus. They fit RMS with a thin layer of tape, but not a good permanent solution. Very decent performance on those.

Those 20.87x images look good.

I have been planning to test the whole range of these objectives and maybe I'll try to find time to do that.

[ray_parkhurst]

Here is the adapter:

https://www.ebay.com/itm/254649662457

[Milou]

Hello,
Just to inform they have been all sold out and taken off the website!