Amateur Astrography: Stitching Together Large Fields of View

[Andy Resnick]

Astrographs are fast (f/4 or less) telescopes with large image circles (say 60mm or more); there are optical design considerations that make the specific designs somewhat more complex than 'regular' telescopes- primarily the strict field flatness requirement. While a 35mm format sensor is significantly smaller than medium-format plates associated with astrographs, by stitching together a few fields of view I can begin to approach that kind of performance. Here's 2 fields of view stitched (using Hugin), each image (stack) taken with a 400mm lens, providing an overall 5 x 5-degree field of view of the North American Nebula in Cygnus:

This image has been so severely downsized that it's hard to really appreciate; there are at least 408k stars filling in 8.5% of the image. If I printed this at maximum size (80 dpi), it would be 8 feet on a side- enough to cover a wall with this level of detail:

 

[Greg Bernhardt]

Nice work Andy! Anyone else take any Astrographs?

 

[davenn]

Nice work Andy! Anyone else take any Astrographs?

Am looking at buying a f4 astrograph with either a 6" or 8" mirror. This will have a distinct advantage over my 9.25", f10 scope

just have to recover from the hugely expensive Christmas holiday airfares
for what that is costing me, I could buy 2 x 8" f4 astrographs optical assemblies

Dave