How far can I "push" an ED66 'Frac? (Gratuitous wibble!)

[Stu]

1 hour ago, Macavity said:

Thanks, Stu! I think we are much on the same wavelength here - Theoretically or via Experience!
I think I'll persist with the Doublet idea, rather than go for a Triplet! Also, whatever theory might
suggest, I have invariably found that VIDEO Astronomy works best (far easier) with f/4 to f/5.  
(Amazing what quite small difference in f-number "photographically" can make in a telescope!)

In it's defense, the Altair Astro is actually f/7, so it could be focal reduced! I have a reasonable
quality 2" focal reducer... and we "VIDEO types" are perhaps a tad less fussed about quality!
0.7x = f/5! - I find my trusty ST102 (f/5) useful for video astronomy - If a tad "blue bloated"? 

Hah. I see you are now a declared "minimalist". For practical reasons many of us may share? 
Don't like chopping & changing telescopes, but maybe I will "SWAP" the ED66 for an ED80...

An F/7 ED102 is tempting though. For some reason I dislike my "ENTRY LEVEL" Solar Scope
(Lunt LS50THa) being my most expensive scope by a country mile...
  

 

Yes, my attempts at minimalist observing (justifiably mocked by my esteemed colleagues on SGL ?) are financially induced at the moment. Hopefully rectified soon, but even so I can't help myself when it comes to dabbling in new kit.

Agreed, f ratio makes a big difference for VA which is why I thought the ED100 less of a good idea. Don't get me wrong, the Altair 102 f7 would be lovely I'm sure, and if you have a mount that will take it and are not so bothered with the cool down time I'm sure that it would give great results. If we are going to extremes, then the ED120 is an absolutely cracking scope for the price, faster than the ED100 having the same focal ratio as the ED80 at f7.5 so you could reduce it down. It would give great results for white light solar with a Herschel wedge and the extra aperture would really help for visual. What's not to like? Obviously it takes it worlds apart from the 66mm, so it totally depends on the what you want to do with the scope, how portable you need it to be etc