StarTools

marty1776 wrote:Here's another question, I was shooting the ring nebula one night and trying different ISO and shutter speeds(aperture the same as I didn't know how to use it yet). I was just trying to see what looked the best once I downloaded them. If you are shooting something, do you always use the same settings? Or do you try a few, find the one you like for that night and shoot a lot at those settings?
thanks

Hi Marty,

Lots of great answers here already (thanks guys! )
It appears that ISO 400 is (for a lot of technical reasons) the most optimal setting for most DSLRs (can point you to an article if interested).
The thing is that at higher ISOs, the camera simply starts 'multiplying' the signal; e.g. it simply starts to count 2, 4, 8, etc. changes in brightness level for one photon collected; the image simply over exposes quicker.
At around ISO 400, the camera really counts 1 brightness level for each photon collected.
SInce post-processing lets you multiply photon counts at will, you're better off counting photons 1 by 1, so that it takes a long time for your camera to reach the maximum count (the count where overexposing starts).

Have you heard of a barn door tracker by the way? A super cheap solutions for allowing longer exposures without (much) star trailing.

I'm very interested in that article about DSLR ISO. I know the theory that point iso 400 as the optimal gain, but it is mora than usual to see DSLR astrophotographers tu use ISO 1600 as standard.

Marty1776, I think it is very usual to have some standard exposures combinations because of calibration frames, read about dark frames in google. When you choose your camera optimal ISO, it is pretty common to establish exposures of 150, 300, 600 seconds and so on as an standard for your sessions. Exposure times mainly depend of your tracking possibilities.

Regards

Alvinillo wrote:I'm very interested in that article about DSLR ISO. I know the theory that point iso 400 as the optimal gain, but it is mora than usual to see DSLR astrophotographers tu use ISO 1600 as standard.

This is the (really thorough) article by Craig Stark;
http://www.stark-labs.com/craig/resourc ... earity.pdf (obtained from http://www.stark-labs.com).

admin wrote:

Alvinillo wrote:I'm very interested in that article about DSLR ISO. I know the theory that point iso 400 as the optimal gain, but it is mora than usual to see DSLR astrophotographers tu use ISO 1600 as standard.

This is the (really thorough) article by Craig Stark;
http://www.stark-labs.com/craig/resourc ... earity.pdf (obtained from http://www.stark-labs.com).

Okay, thanks!!