Amateur Astrography: Stitching Together Large Fields of View

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SUMMARY

The discussion centers on the use of fast astrographs, specifically those with f/4 or less and large image circles of 60mm or more, for amateur astrophotography. Participants highlight the optical design complexities, particularly the need for strict field flatness. Techniques such as stitching multiple fields of view using Hugin software are discussed, demonstrating the capability to create expansive images like the North American Nebula. Users also share personal experiences and considerations for upgrading to larger f/4 astrographs, emphasizing their advantages over traditional telescopes.

PREREQUISITES
  • Understanding of astrograph specifications, particularly f-stop and image circle.
  • Familiarity with image stitching software, specifically Hugin.
  • Basic knowledge of astrophotography techniques and equipment.
  • Awareness of optical design principles related to field flatness.
NEXT STEPS
  • Research the specifications and benefits of f/4 astrographs.
  • Learn advanced techniques for image stitching with Hugin.
  • Explore the optical design considerations for astrophotography.
  • Investigate the differences between various telescope mirrors, such as 6" vs. 8".
USEFUL FOR

Astronomy enthusiasts, amateur astrophotographers, and anyone interested in enhancing their astrophotography skills with advanced telescope equipment and techniques.

Andy Resnick
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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:

small%20astrograph_zpsypfcin3i.jpg


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:

dark%20spot%202_1h_7m%20-%20dark_3h_21m-1_zpsj1sehnss.jpg
 
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Nice work Andy! Anyone else take any Astrographs?
 
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Greg Bernhardt said:
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 :frown:
for what that is costing me, I could buy 2 x 8" f4 astrographs optical assemblies

Dave
 
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