Threads Inside St80 Focuser?

[perkil8r]

Can anybody please tell me:

1, what size the threads are inside a standard R&P focuser on an ST80

2, what they are meant for

3, if "2" is not "for a filter" could a filter be used somehow in there?

Cheers

[JamesF]

My ST80 isn't to hand at the moment so can't check, but are you sure they're actually threads rather than just rings? It could be that cutting grooves into the inner surface of the focuser drawtube reduces internal reflections?

James

[perkil8r]

Just checked, they are definately threads.

[JamesF]

In that case I have to admit that I have no idea as to their purpose. I can't see how they'd work with a filter. I'm intrigued now. Would seem an odd thing to have done for no reason, certainly.

James

[perkil8r]

The focus tube is silver on the outside. Into the end screws the eyepiece holder (as I will call it) which has the two thumb screws and t thread on the end of it. At a rough guess the threads must be about 33mm maybe 34? I've not measured it as I no longer have a working vernier caliper, and no thread gauges. I'm kinda hoping somebody has asked before and found an answer, and or some filters that will fit.....