[Aavso-photometry] Adequate FOV size?

[Arne Henden]

Necessary field size is largely dependent on the brightness of the
target object and the distance from the galactic plane.  I rarely
if ever have trouble at 11.5x11.5arcmin with the 1.0m telescope
for the "sweet-spot" objects around 14th magnitude, but quite
often have trouble getting good comp stars when trying to observe
some 9th magnitude object.
   Larger fields often have other problems, such as vignetting,
poor flatfielding, curved focal plane (so not all objects are
in focus), and optical distortions.  Probably 20x20 is a convenient
compromise.
Arne

Keith Graham wrote:
> I see that a large FOV (30'x30') appears to be favored by some. I must say that I have a 11.5'x11.5' fov with my ST9e and LX200 12". It is a very rare occasion when I cannot get the variable and 3 comps from an e chart within my fov. For photometry, I will use only f charts when available, and these are well within my 11.5' x 11/5' fov. I will resort to the e charts when no f chart is available, but even then there are plenty of comps from which to choose that lie in my fov.  
> 
> Cheers,
> 
> Keith Graham
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