C-mount dust caps for M25x0.75 nosepiece threads?

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Ichthyophthirius
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C-mount dust caps for M25x0.75 nosepiece threads?

Post by Ichthyophthirius »

Hi,

I'm wondering if anyone has tried to use cheap plastic C-mount dust caps (male) as dust caps for M25x0.75 microscope nosepieces?

And if so, do they fit nosepieces from Zeiss Jena, Nikon or Leica, specifically (all nominally M25x0.75 but have quite different "play")?

Example: https://www.ebay.com/itm/252493717761

Regards, Ichty

genera
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Post by genera »

You can't count on it, though you may find some are OK for home / hobby use.

I just tried threading 3 C mount plastic plugs, from 2 different makers, into 3 female M25x0.75 adapters. Of all the combinations; 2 of the plastic plugs would screw into one of the 3 female adapters about 1/2 to 3/4 turn. The other plastic plug screwed into the same adapter about 1/4 turn. The other 2 plastic plugs could be forced to engage the female threads just at the very beginning of the threads.
-Gene

Macro_Cosmos
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Post by Macro_Cosmos »

https://www.thorlabs.com/newgrouppage9. ... up_id=9581
Thorlabs have these caps.

There's also lots of metal ones on ebay, I'd take them over plastic ones.

Ichthyophthirius
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Post by Ichthyophthirius »

Hi Gene,

Thanks for checking this out!

After I wrote the question, I actually found a C-mount plug (male). It has a very long thread (at least 10 turns). Even tough, it fits all the way into a plastic M25 objective vial lid, but only 1/4 turn into a Zeiss Jena M25 nosepiece ... I'm wondering if the cheap C-mount plugs with only a few turns would do a better job.

Hi Macro,

The Thorlab plugs would likely damage the nosepiece threads (C-mount is 25.4 mm nominally, so sligthly bigger than M25); metal is out of the question. I also need quite a few of these plugs so $1-2 is more feasable :wink:

The only other affordable option I can think of would be to cast some myself using silicone.

Regards, Ichty

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Post by JKT »


Macro_Cosmos
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Post by Macro_Cosmos »

Ichthyophthirius wrote: Hi Macro,

The Thorlab plugs would likely damage the nosepiece threads (C-mount is 25.4 mm nominally, so sligthly bigger than M25); metal is out of the question. I also need quite a few of these plugs so $1-2 is more feasable :wink:

The only other affordable option I can think of would be to cast some myself using silicone.

Regards, Ichty
How about an M25-RMS adaptor with an RMS metal cap glued onto it?

Yeah that extra 0.4mm could be a bit worrying, though I'd assume the threads on the cap will be damaged, either way, not nice.

M25x0.75 to RMS: https://www.ebay.com/itm/Adapter-RMS-Th ... SwMmBV5GQd

Glue this into it:
https://www.ebay.com/itm/NEW-2-pcs-Biol ... Sw9N1VwV-X

I'd say a plug works too. The lab I use just covers the ports with gaffers tape and toss a rubbish bag over the microscope, words too.

This should work as well, I use them for my SM1 tubes (not from same seller). SM1 is 25.4mm, same as C-mount.
https://www.ebay.com/itm/Clear-Lens-Cap ... SwsBtaE-rf
JKT wrote:Cheap they are not, but...

https://www.thorlabs.com/newgrouppage9. ... p_ID=11674
Those are RMS threads, which is like M20.32x0.706 or close.

JKT
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Post by JKT »

Macro_Cosmos wrote: Those are RMS threads, which is like M20.32x0.706 or close.
Look a bit lower on the page. RMS, M25x0.75, M26x0.706 & M32x0.75 - all available. I'll be needing one with the canister. :)

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Post by Macro_Cosmos »

JKT wrote:
Macro_Cosmos wrote: Those are RMS threads, which is like M20.32x0.706 or close.
Look a bit lower on the page. RMS, M25x0.75, M26x0.706 & M32x0.75 - all available. I'll be needing one with the canister. :)
The RMSCP1 has internal RMS threading; with the addition of the RMSA2 adapter, it is also compatible with objectives with M25 x 0.75 threading.
That's it though. This line would be redundant if there's native M25 caps, right?

There is no dust cap for M25 or M26 from Thorlabs unless one uses an adaptor. There is however various threaded lids for objective lens canisters. Am I missing something here?

Here's a nikon nosepiece that shows 2 Nikon branded caps, which I assume are either M25 threaded or plugs.
https://www.ebay.com/itm/Nikon-Eclipse- ... SwJiRejdBh

So maybe Nikon sells them, worth asking customer service, perhaps.

Ichthyophthirius
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Post by Ichthyophthirius »

Macro_Cosmos wrote:This should work as well, I use them for my SM1 tubes (not from same seller). SM1 is 25.4mm, same as C-mount.
https://www.ebay.com/itm/Clear-Lens-Cap ... SwsBtaE-rf
That's a great idea; thank you! I think I'll try this.

JKT
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Post by JKT »

Macro_Cosmos wrote:There is no dust cap for M25 or M26 from Thorlabs unless one uses an adaptor. There is however various threaded lids for objective lens canisters. Am I missing something here?
Nope - I am. Namely the part about male thread. ](*,)

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