Takahashi FS60CB: finally in focus with everything

[Fedele]

hi

I recently bought an FS60CB and I immediately ran into the known problems of backfocus and short focuser.
The use I have to make of the telescope involves the use of heavy and accessorie very demanding  in terms of backfocus: solar observations with Quark+ turret, Diagonals of 2", Baader cool Ceramic 2 "+ turret, etc ....
The definitive solution I found, which solves the focus problems with all this in a SAFE and STABLE way, was to mount an FTF 2025 BCR (which I had from the previous FC100DL). But not with the dedicated SI flange, as it takes up space and in the end the system is 7.5 cm long as with the original fok.
Therefore I had a flange made here in Italy, by the "Officine Otttiche e Meccaniche COMA di Adriano Lolli", which:
- was ultrashort
- that guarantees solidity to heavy optical trains without bending
- that he did not do vignetting
Lolli has created this magnificent flange which at the moment still has to be anodized in the same color as the focuser.
To give you an idea of the system, I go into focus with Maxbright II turret + T2 32 Baader + 2 "nose (total backfocus 148 mm) and there is still 22 mm of travel left, and this WITH NO GPC!

 

 

Edited March 24, 2022 by Fedele

[Fedele]

This was the first attempt

[Highburymark]

Very nice solution.

[Fedele]

[Fedele]

A clarification, which I have mistakenly omitted. With Maxbright II Turret and Baader Cool Ceramic 2 ", you need a 1.7 GPC.
The alternative is to have me make a thinner flange

[Stu]

3 minutes ago, Fedele said:

A clarification, which I have mistakenly omitted. With Maxbright II Turret and Baader Cool Ceramic 2 ", you need a 1.7 GPC.
The alternative is to have me make a thinner flange

That matches my previous input that you would struggle without a GPC with BVs and the Coolwedge. I guess there Is limited scope to reduce the distance further, your flange looks pretty short now?  Plus even with the GPC you should still be getting about 2 degrees with your 25mm Plossls, plenty for full disk views. In fact you would like want higher power I should think?

Nice setup, I’ve done similar with the standard flange and a x2.6 GPC With 25mm Orthos which gives higher power but still comfortable full disk views.