Darks library

[Gvarouha (George)]

Just after some thoughts on a dslr dark library.

I was thinking of shooting some darks with different exposures and at different temps just to try and save some valuable imaging time.

My camera is uncooled so there is always some temp variation.

Question is how many different temps should I shoot for to build a library eg every 5,10 degrees?

Cheers

[rustigsmed (Russell)]

The closer the better, depending on how much time you have!
i never went too overboard on darks.. flats and enough lights seemed to me to make a bigger impression on image quality.

[Ryderscope (Rodney)]

Originally Posted by Gvarouha

Just after some thoughts on a dslr dark library.

I was thinking of shooting some darks with different exposures and at different temps just to try and save some valuable imaging time.

My camera is uncooled so there is always some temp variation.

Question is how many different temps should I shoot for to build a library eg every 5,10 degrees?

Cheers

My rule of thumb George with the DSLR was to use 20 darks for each image processed. As you are taking the darks the temperature will vary anyway so you will finish up with a wide range. Try to match them as close as possible but within a couple of degrees should be sufficient. If you are using a Canon and Backyard EOS software you should be able to capture the sensor temperature in the file name which makes it easy to sort out the darks according to temperature.

[Somnium (Aidan)]

Sub length is also important . It needs to be the same for dark and light subs. So you may be tying yourself to specific sub lengths.

[Gvarouha (George)]

Thanks for the replies.

Seems that the range of temperatures through one imaging session is the biggest issue.

This cloud over Sydney doesn't look likes it's going anywhere for a while so there's plenty of time to experiment with darks.

[cfranks (Charles)]

I think it depends on what software package you use to process your images. Some (most?) will scale the Dark to match temp and exposure. I only use PixInsight which does, and I only use Master Darks of 900 secs and 30 secs. TheSkyX seems to scale the darks for the Autoguider when stored in the Image Calibration library so I just use a dark of 10 secs, being my maximum guider exposure. Saves a lot of time, getting calibration files in increments of 5 mins or so.

[Gvarouha (George)]

Originally Posted by cfranks

I think it depends on what software package you use to process your images. Some (most?) will scale the Dark to match temp and exposure. I only use PixInsight which does, and I only use Master Darks of 900 secs and 30 secs. TheSkyX seems to scale the darks for the Autoguider when stored in the Image Calibration library so I just use a dark of 10 secs, being my maximum guider exposure. Saves a lot of time, getting calibration files in increments of 5 mins or so.

That's a really good point, didn't even think of the scaling.