RE: Scope City Story - LX200 GPS 12 & NexStar 11 GPSfrom my perspective, David, the shorter focal length of the typical richfield refractor coupled with a german eq mount is the easiest way to taking good pictures/images with the least muss and fuss. The short focal length is not nearly as sensitive to alignment issues and tracking issues, so you will get better pix with less work. Besides the really "WOW" stuff are huge nebulae anyway such as NGC7000, California Nebula, Rosette etc.
But this is not an imaging list so let's not get too much into that stuff here. You can go to Yahoo groups' TAC_Imaging to get into more details.
rdc
----- Original Message -----
From: David Samuels
To: 'sf-bay-tac@No-Spam'
Sent: Thursday, April 17, 2003 1:03 PM
Subject: [TAC] RE: Scope City Story - LX200 GPS 12 & NexStar 11 GPS
>In general, if I had to do it all again, for the purposes of astrophotography, I wouldn't buy a new scope off either of these companies. I'd buy a great third party mount (G11/Gemini, AP, etc - there are now many great mounts on the market), and buy a smaller faster OTA to start, *maybe* some day buying a used SCT OTA (C8 probably). SCT's are not great beginner CCD OTA's. They require a lot of accuracy in tracking and guiding, have big focus shift problems, and tend to have very small fields with the average beginner to intermediate chips.
Are you saying that a SCT is bad for the job or bad for newbies? I am learning that a german eq mount doesn't have a problem pointing at 90 degrees up from the base while cameras and things are attached - the fork-mounted SCT can't.
You say that an SCT is a bad beginner CCD OTA - due to accuracy, tracking, guiding, focus shift, small fields of view. Isn't the lens speed resolved with f/6.3 or f/3.3 reducers/field flatteners? The LX200 has a primary mirror lock and microfocuser. Would that be sufficient to solve the focus shift problems. As far as tracking and guiding goes, if it works within spec, are there still tracking and guiding issues? What issues are those? How do SCT owners resolve them?
Thanks for the input.
Dave