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Old 23-04-2012, 06:58 AM
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dvj (John)
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Which One is Faster? F/3 or F/6

So here is a question to you tech theory types. An 8-inch F/3 or an 8-inch F/6. Which system is faster for astrophotography?

Looking at Nyquist sampeling information:

Let's match the pixel micron size to our FL's

8" f/3 with a CCD camera of ~2 micron pixels
8" f/6 with a CCD camera of ~4 micron pixels

Assume that both telescopes are of the same optical design and our CCD cameras have the same QE.

Aperature is the same, and we have optimized our pixel size for our focal length for coverate of at least 2 pixels by the Airy disc. Which would be a "faster" optical system for CCD Imaging?

Although the field of view is different, whould I actually gather more nebula in a shorter period of time with the F/3? Me thinks not.
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