mismatched microscope objective to adapter

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bs0604
Posts: 40
Joined: Tue Feb 19, 2013 8:09 am
Location: Sarasota FL

mismatched microscope objective to adapter

Post by bs0604 »

I have received all the pieces necessary to build an extension tube but find that the microscope objective and adapter "plate" I ordered don't match. I purchased from Thor Labs a Mitutoyo M Plan Apo Objective and from Amazon a 0.8" x 36 TPI RMS thread for microorscope objective to 52 mm lens adapter. Came from China without any markings or paperwork so I assume they sent me what I ordered. However, the microscope objective is too large to screw in to the lens adapter. Do you know what adapter I should be ordering to fit this Mitutoyo objective and from where to order the adapter (preferably in the US as it took 3 weeks for this wrong adapter to reach me)?

Chris S.
Site Admin
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Joined: Sun Apr 05, 2009 9:55 pm
Location: Ohio, USA

Post by Chris S. »

bs0604,

A partial answer: For a standard (not BD) Mitutoyo objective, the thread size is 26mm x 36 TPI (a good source for learning thread sizes is here). We would expect that your RMS (0.8 inch, or 20.32mm) adapter would be much too small.

Offhand, I don't know of any US sources for a single-piece Mitutoyo to 52mm adaptor. Perhaps others do. Looking at Thorlabs selection of thread adapters, I see a path for assembling three separate pieces to make the transition, but this seems clunky, expensive, and likely to leave more separation than ideal between your objective and converging lens.

If you do order from overseas, eBay vendors jinfinance and rafcamera are known-good sources. (Rafcamera also has a Web-commerce site separate from eBay.)

Cheers,

--Chris S.

hero
Posts: 72
Joined: Mon Jul 17, 2017 12:38 pm
Location: California

Post by hero »

According to various sources, the thread size is M26 x 0.70 (36 TPI). So for example, this one

https://www.rafcamera.com/adapter-m26x0-7-to-m42x1

will adapt the male Mitutoyo M Plan thread to M42.

This one

https://www.amazon.com/Generic-Microsco ... m26+to+m52

will adapt to M52, but it's not presently available. Here's another but I've never seen this site before:

http://www.cnscope.com/index.php?route= ... uct_id=256

And one from ebay:

https://www.ebay.com/p/Metal-Converter- ... /933213199

You could also go the Thorlabs route and buy two adapters, it doesn't seem they have a direct M26 x 36 TPI to M52. But the key is that the Mitutoyo M Plan thread is M26 x 36 TPI.

If you think the M Plans are tricky to find adapters for, the M40 x 36 TPI adapter for the Mitutoyo BD Plan was ridiculous.

bs0604
Posts: 40
Joined: Tue Feb 19, 2013 8:09 am
Location: Sarasota FL

Post by bs0604 »

thanks. the one I ordered (and does not fit) came from CNSCOPE so I'll wait another day and if no one can point me to a quicker (US) source I will try and order the correct adapter from CNSCOPE as at least I know they are reliable, although coming from China is a 3 week wait.

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