Both cameras produced hundreds of photos of the night sky from fixed tripods - which make for excellent star trail photos once stacked using free StarStaX software.
My point and shoot produced 252 usable frames, which is typical of its battery life. I get fewer in winter when the cold drains the battery faster, but in 50°F air this was normal. My DSLR was set to JPEG instead of RAW to allow for as many photos as possible. I only ended up with 850 images over about 3 hours. I suppose I could have used RAW format for this, because it didn't come close to filling up my 64GB memory card.
I still need to learn to tether my DSLR to my laptop and buy an AC adapter for unlimited shooting! But for now, 3 hours in the can is a good chunk of time.
Ugh, I just realized as I was typing my photo specs into the pics below that I had my camera stopped down for no good reason. I could have opened it up to f/4.5 for some brighter images. Oh well! On a positive note, I didn't have to Photoshop any planes out of the images because there were only a couple and they just so happened to fly in the general direction of the star paths. Can you spot them?
|Stack of 850 photos, each at ISO 800, 18mm, f/5.6, 15 sec|
|Stack of 252 photos, each at ISO 800, 6.2mm, f/2.7, 15 sec|
Canon PowerShot A3100 IS