"Rick Johnson" wrote

As as stop gap measure I was thinking of that STL lens you mention with my
Optical Craftsman 6" f/4. I'll have to replace the spider as it is
warping so I couldn't keep it in collimation. Move the scope to the other
side of the meridian and it lost all collimation. It had been adjusted so
many times over the 45 years I've owned it it just won't hold any more.
The mirror in that scope is fantastic. It easily beat the best RV-6
mirror of the era in our club at high power even with the huge secondary.
So if I can get it to hold collimation and that lens works it would be a
cheap way to go. As is, with the ST-7 it has almost exactly the same FOV
as the 14" with the STL-11000! So if you hear anything about those at f/4
let me know. Think they are designed for f/4.5. With the 11000's large
chip that may not work at the corners.


Rick,

You might have to put a new focuser on the 6-inch F/4 because focus is so
tight at that f-ratio. However, with the good mirror I'd bet that you could
get the OC scope to work with a coma lens. My friend with the Cave 6" F/4
put a Moonlight focuser on it and uses a coma corrector from Baader
(http://www.alpineastro.com/). He's using a camera with a chip about the
size of an ST-7's. However if the coma gets too much in the corners of the
STL-11k just cut the corners off! I got use to round images back in my days
of using a Lumicon 4x5" camera (3.8" circle of film exposed). You would get
a huge field even if you lost a little and it would be fun getting the old
6-inch scope working for imaging.

George N