Quote:
Originally Posted by Matthewstewart
@Dave "Your Mak is a bit slower than ideal for photography (at f/11), which means you'd need very long exposures (4x as long as an f/5.6 refractor)" I was looking into this and apparently it's a myth? http://www.stanmooreastro.com/f_ratio_myth.htm
Matt |
It's the same maths - it's just as much of a myth to say that f ratios don't matter. The article you linked to assumes you keep the aperture constant and have an unlimited detector (CCD) size.
Neither is true in your case - you're choosing a scope, thus also choosing your aperture. Furthermore, the image sensor doesn't change size - so when the f ratio increases, your framing changes.
If you keep the framing (ie focal length) and sensor size constant - such as to fit the Orion Nebula into the whole frame - then f ratio matters because it inversely correlates with aperture.