Another M13!

I was trying to image M13 with an f3.3 focal reducer. The setup is C14+.33 reducer+CFW8A+ST-10XE. Processing was in MaxImDl, CCDSharp and Photoshop.

The .33 reducer in this setup actually produces a working f ratio of around f4.5. I would probably need a 15mm spacer to actuall get f3.3. Even at f4.5 I get lots of distortion in the corners. The shot was LRGB 15-15-15-25.

Are there any good 3.3 reducers out there that cover the ST-10 chip in an f10 setup?

Thanks for looking...Ken

Attached Image:

>Even at f4.5 I get lots of distortion in the corners>>

Just a word about optical terms. Distortion is a simple displacement of a star image from its ideal position. It is the aberration common in inexpensive binocular eyepieces which show up as a bending of straight lines at the edge of the field of view (telephone poles bend away from the center as you sweep the bino across the field).

Distortion does NOT cause elongation of star images at the field edges (this is astigmatism). Distortion does NOT cause stars to have seagull or comet shapes (this is coma). Distortion is not the same as a lack of a flat field (this is field curvature, which also does not cause mishapened stars, rather it causes stars to be slightly out of focus at the field edges).

End of optics lesson

Roland Christen

I don't know if he has adaptors for a C14, but Ted Agos makes focal reducer adaptors for Meade SCTs. He knows quite a bit about focal reducers and you could always drop him a line.
He's here:
http://www.ziplink.net/~lester/FLR.html

dan kowall

Ken, Great M13. I have an optec 3.3 Nexgen. I purchased it for a C11. I don't know which reducer you have, but I can lend you mine to check out if your interested. Joe