Brain Freeze - when to use Darks

[Fordos Moon]

Having a senior moment.

What kind if imaging requires dark frames and what doesn't?!

For example Deep Sky Stacker uses them when processing say M42 DSLR captures. But use DSLR to capture moon and PIPP and Registax don't.

If anyone has a nutshell they can done it up in it will save me an hour reading all my notes to work out why I'm having a moment!'

[JamesF]

There are no hard and fast rules that I'm aware of, but I'd say darks become more useful as the target gets fainter and exposures get longer. In a shot of the Moon then the Moon will tend to dominate the image and the short exposure time will help limit some forms of noise whereas it's quite possible for noise to dominate faint areas in a multi-minute exposure.

James

[cgarry]

I also assumed that dark frames were only useful for long exposure imaging where the signal to noise ratio was low.

Having said that, I am very interested in what other people's opinions are on this as I am thinking of adding dark frame (and flat frame) support to PIPP.

Cheers,

Chris

[Fordos Moon]

Thanks fellas. :-)

[JamesF]

Having said that, I am very interested in what other people's opinions are on this as I am thinking of adding dark frame (and flat frame) support to PIPP.

The way I work I probably wouldn't use darks/flats with PIPP, but there's every possibility that I'm not a representative sample

James

[cgarry]

The way I work I probably wouldn't use darks/flats with PIPP, but there's every possibility that I'm not a representative sample

James

I don't think I would use them either, but you never know I could be missing something!

Cheers,

Chris

[ollypenrice]

In fast frame imaging ( Webcam-Registax ) you have so many images, and they are so misaligned, that darks probably won't help at all. I might be wrong because I hardly do anything like this other than on the sun. When images are misaligned the same bad pixel isn't imaging the same part of the target so its bad reading will be averaged out by all the good ones. Its error might, in effect, be divided by 500 or so, depending on your stack size. In DS guided imagng you can also forget darks if you dither guide and use a bad pixel map, though I still use darks myself.

Olly