DeepSkyStacker and subtracting Flats issue

[EzyStyles]

Hi Guys,

Not sure if you guys noticed, but when using deepskystacker then subtracting my flats from my light frame, image becomes more grainy??? I have tested without subtracting flats, it is much more smoother and less grainy. i normally take 10 flats then average so it can't be my flats.

Anyone else experience with this?

cheers


using v2.6.3. tried v3 also does the samething.

[h0ughy]

have you looked in his bug fixes whether it has been listed previously as a bug?

[seeker372011]

no I dont seem to have the problem..I have so much dust on my sensor I could not manage without flats
I seem to remember reading somewhere -think it was in Jim Solomon's astrophotography cookbook-that incorrect flat exposure duration-in particular underexposure- can add noise

[EzyStyles]

Thanks for the info guys. couldnt find any update on deepskystacker.

you might be right seeker. hm have to investigate.

heres what im talking about. the left one without flat and the right with flat.

[seeker372011]

you can also ask at the DSS yahoo group-Luc usually is there and he is very helpful

[higginsdj]

Sorry for being pedantic but you aren't 'subtracting' your flats are you? Darks are subtracted but flats are a division process.

Cheers

[EzyStyles]

not subtracting my flats at all. in DSS it does it for you automatically. im just thinking must be the moon glow.

[higginsdj]

The Moon will reduce your SNR significantly just because it is brightening the atmosphere through which you are imaging (even though you may not be able to see the brightening).

Cheers