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PVS-7 Objective Assembly O-ring (part MS28775-032)

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#1 DMala

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Posted 17 March 2019 - 09:45 AM

The one on mine just shredded off while removing the Envis lens assembly last night. I ordered already two replacements online (ORingUSA seems to carry mil-spec o-rings). 

 

Question: since I expect to frequently exchange the Envis assembly with the C-adapter, is it worth it to put it back? I do not expect use under rain, splashes, etc., and with all of my astro equipment after use I always leave the item in the open in a dry environment at least overnight, to dry any dew residue.

 

I was just thinking that those gaskets are not designed for frequent on-off use.



#2 Vondragonnoggin

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Posted 17 March 2019 - 09:54 AM

O-ring likely to ensure sealed purge is intact. Since you use it for astronomy, there is no purge (nitrogen purge lost as soon as the objective assembly removed and changed for c-mount adapter). I wouldn’t worry about keeping the o-ring.

 

I have an envis c-mount lens and sometimes use it on my pvs-7. No o-ring. I unscrew the nosepiece that I usually leave on the pvs-7 and screw in the envis lens.

 

It probably assists with water resistance also, but as you mentioned, your not taking it out in the rain or going swimming with it, so no worries.


Edited by Vondragonnoggin, 17 March 2019 - 09:57 AM.

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#3 Eddgie

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Posted 17 March 2019 - 04:14 PM

Agree.  Serves little purpose on a device that is changed back and forth from C mount to Mil-Spec.  Also, removing it makes it much easier to thread on the different fronts. 




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