In the interest not to hijack a another thread, "Clarification: Is focal ratio the supreme factor in integration time?" I 'm starting this one. I seen a post on the other thread & I'm wondering about the physics of a photon. The post from the other thread (used with permission)
I recall, probably from the old film days, a truism:
F/ratio applies to extended objects while aperture applies to point sources.
So greater aperture gets you fainter stars no matter what the f/ratio is.
But faster f/ratio gets you more nebulosity.......
Now mix in focal length, pixel size, pixel sensitivity, exposure length, ISO, number of sub-frames, which stacking algorithm used, darks, lights, flats, bias, and what-have-you, stir it all up well and the result?
The good old 'it depends'.....
I know I'm pretty dense, but the way I see it, a photon of light is just a photon of light. Vega is a point source ( so they say), so aperture rules. If you put a billion others stars around Vega, now it becomes an extended object. The photons emanating from it is still just photons.
1: So how does the laws of physics change the photon of light depending on its origin?
2: How does your imaging chip know where that photon of light originates?
I realize that I'm dumber than a box of rocks, so explane it to me so a 5 year old can understand.
Edited by Galaxyhunter, 22 October 2019 - 12:26 PM.