TAL 8x50 finderscope stubborn objective retainer ring.

[DaveGibbons]

Hi All,

I picked up some Tal gear the other day, all in very good condition if a little dusty. The Tal 8x50 finderscopes are superb bits of kit but mine does have a little bit of fungal growth on the inside of the doublet objective. I have tried carefully to drift loose the retaining ring (see photo), but it does not seem to want to move. Now I have been sensible and not applied too much force but just wonder has any member taken this ring off before and was it a pain to get off. I am hapy to purchase the correct  tool to remove the ring -they are about a tenner on flea bay. Just wondering if I missed something?

 

Edited October 24, 2022 by DaveGibbons
Spelling correction

[Peter Drew]

I've not dismantled one of these but I have done similar ones.  The obvious correct tool is a "lens spanner" but if the drift method hasn't worked then it's probably too tight as yet to unscrew with the spanner.  I would suggest introducing a small amount of penetrating oil to the threads and let it stand front downwards for a while to help free any corrosion.  The lens is most likely cemented so the oil shouldn't penetrate the join and you will be cleaning the lens anyway.

Good luck.     🙂  

[Knighty2112]

+one for the light oil in the thread and let it soak in for 24 hours then try it after that.

[Rusted]

I use screw adjusting engineers dividers for removing rings.
The larger models are pretty stiff and provide accurate spacing to fit the slots in the retaining ring.
Some filing or grinding of the  divider tips might be useful to give flat working surfaces in the slots.

[DaveL59]

Not tried to dismantle mine as yet but I think the clue is in your picture:

I expect that hole contains a small set screw that'd lock the lens cell into place once it's been screwed in to the correct distance. If that's the case be sure to count the turns as well as note/mark the position of the lens ring so you get it set back in the right place on refitting.

[PeterW]

The synta finders have a threaded objective cell you can screw in and then lock with a second threaded ring to set focus. Not removing a locking screw is something I “discovered” when repairing some old binoculars, thankfully I did t do too much damage and they went together again.

Peter

[DaveL59]

The small TAL-M with the finder in-built to the focuser has a similar set screw to hold the finder objective cell, hence I noticed that wee hole right away 😉 Checked my 8x50 finder and yep, is threaded with a set screw in there:

[DaveGibbons]

Thank's for all your advice! unfortunately the small set screw on my finder is chewed up and could not be removed.  I have managed to clean the inside of the objective from the other end of finder tube. I removed the eyepiece assembly and very carefully used some baader wonder fluid with lens tissue and microfibre cloth attached to a small soft paint brush to remove all the fungus and leave the lense almost smear free...good enough for me !

cheers

Dave

 

[DaveL59]

ouch that's a shame, tho they do tend to seize so are easily broken. It may be possible to drill it out with an easy-out if you can get one small enough that is with some freeing oil and heat (soldering iron) to ease it a bit first. As it is you found a way, been there myself with an old Hensholdt Wetzlar dialyt bino and used a very similar method 🙂 

Edited October 27, 2022 by DaveL59