Mardi 4" achromat, ETX-70, 8"cat. Whitepeak Lunar Observatory Website
G11/Gemini-2/OPWB Canon 60D (unmodified) with 18/55mm kit lens and "nifty fifty" lens Assorted M42 screw mount lenses (28mm thru 300mm) Celestron 102GT refractor (Costco special) 8/10 inch astrograph someday. DeepSkyStacker 3.3.2 StarTools 1.3 http://www.astrobin.com/users/StarGale/ http://everettastro.org/
Quote:Dave,I think you may be mixing adages here. The adage I know is to have your sampling at about half the seeing, not half the limiting magnitude. The limiting magnitude will be tied to your light pollution and not tied to your turbulence or blur level. Bright steady skies can support higher magnifications (higher sampling rates) than dark turbulent skies.Craig
Quote:Hi Craig,I want to compare to setups resulting in the same number of photons delivered to each pixel on average. I am limited by the precision of my mount to a certain length subexposure for a given focal length. I can either buy a lens 1 stop faster or I can take twice as many subexposures. The resolution should be identical. Is the SNR lower for the slower lens? If so, is it because the subexposure is twice as long or because there are twice as many subexposures?
Quote:Craig, Does this method of measuring the seeing work accurately with a DSLR since it has a Bayer matrix and an anti-aliasing filter? For example, the seeing is 2", but you are imaging at 2.5"/pixel. You won't be able to measure seeing below the image resolution will you?
- Jared Willson