I agree in principle with all this, Mike. In practice, for some reason, my present camera will not allow an ISO bigger than 100 for exposures longer than a second. So, for bright celestial objects I jack it right up to 3200 and keep the exposure short; but for constellations, where faint stars need to be brought out and a longer exposure is needed (so the dimmest ones are distinguishable from noise) I'm stuck with ISO 100. Fortunately, the low ISO means the resulting image can be massively enhanced without the noise going through the roof.MikeOxon wrote:I always enjoy night sky photos and took the opportunity to take a few while down near the equator. I particularly liked those you showed earlier of the planetary conjunction.
As you wrote, a lot is in the processing but I would add to always use the widest possible aperture on the camera, set a high ISO, and use a fairly wide angle lens. Unless you have a sophisticated mount, the earth's rotation will blur the star images with exposures of only just a few seconds, of you try to zoom in too much!
For processing, I start by using the 'levels' control to cut out all the grey tones and make the background 'black' - this is why high-ISO noise doesn't matter, because you remove it anyway. Then I use the brightness and contrast controls to get as many stars visible as possible, without noise starting to appear.
Mike
Scenic shots, of course, need some grayscale, as do shots of nebulosity. Enhancements that bring out stars beautifully risk losing the contrast between the mountains (or other setting) and the sky. They also turn the Andromeda Galaxy into an increasingly small spot - so compromise is necessary.
I'll never get brilliant results with a cheap, small-sensor camera, but my aim is only to do the best I can with the equipment I have.
Guy