Calibration images?

caj1311 (Cindi) · #1 08-01-2016, 03:09 PM

Are you all sick of my questions yet?

Can someone give me a quick run-down (or direct me to a good online resource) regarding calibration images? I am going to be trying to do both planetary and (eventually) DSO photography, and I am trying to understand exactly what calibration images (darks, flats, bias) I am going to need for each? How many? And what is the best of way of taking them? I am going to be using a DSLR camera (Nikon D810)...

Somnium (Aidan) · #2 08-01-2016, 03:24 PM

when doing deep sky imaging you should take dark frames and flat frames.

Dark frames are best taken at the same temperature your camera's sensor is at the time of imaging. so because you do not have a cooled ccd which you can set the temperature accurately, you should take dark frames either during or after your imaging session. dark frames should be taken at the same exposure time and ISO as your light frames. take darks with your lens cap on. take around 10 - 20. these frames will remove any consistent noise that is a part of the electronics at that temperature (noise is your enemy when trying to capture faint objects)

Flat frames should be taken during dusk or dawn (unless you have a light box). you can rack your focuser out and/or put a white t-shirt over the scope to create an evenly illuminated field. flat field images remove the vignetting, dust motes or other issues to do with your optical tube. i have found that flat fields are essential if you want to stretch your images and bring out subtle details, otherwise you are likely to end up with a uneven image that is difficult to correct. take 10 - 20 as a rough guide

rustigsmed (Russell) · #3 08-01-2016, 03:30 PM

http://www.iceinspace.com.au/63-211-0-0-1-0.html

at this time of year go for dusk (or dawn) flats. with a DSLR you can set it to the auto exposure setting which makes it a lot easier - you just start clicking away - I generally increase the ISO the darker it gets. On canon's this is Av function I am not sure about Nikons...

caj1311 (Cindi) · #4 08-01-2016, 04:20 PM

Quote:

Originally Posted by rustigsmed

http://www.iceinspace.com.au/63-211-0-0-1-0.html

at this time of year go for dusk (or dawn) flats. with a DSLR you can set it to the auto exposure setting which makes it a lot easier - you just start clicking away - I generally increase the ISO the darker it gets. On canon's this is Av function I am not sure about Nikons...

Thanks - this is just what I was after.