Re: [APML] Tak CN-212 question

[Gene Horr <genehorr@texas.net>]

Antonio Agnesi wrote:

> does anyone use such scope for astrophotography in Newton configuration? I
> heard that its image-shift is usually far less than in most SCTs
> (Meade/Celestron): can you confirm this?

I haven't personally used it for astrophotography, but I know an owner
that has.

In the Newt configuration (with the corrector) it is very good for 
both film and CCD work.  Mirror shift is almost undetectable.  About
5% of his 1 hour+ images had detectable shift with 35mm @ 8x10 
prints, but you had to look hard to see it.

The Cassegrain configuration was less usefull for film.  While mirror
shift was far less than mass market 'scopes, it was still present.
I would estimate that 25% of his images had detectable shift. He
was using a separate guide scope in both situations.

If you are planning on using the Cassegrain configuration for 
film imaging I would consider an off-axis guider a necessity.

Gene Horr
genehorr@texas.net

--  APML Archives at <http://astro.umsystem.edu/apml/>  ---
             Unsubscribe at <majordomo@seds.org>