how to get less noise or grain

kajouman
06 Jun, 2018 20:28
hello all, in my pictures i always see some king of noise or grain.

i always use darks,and  flats too sometime.

its not direct the background..but nebula also.

is it just  not enough data  ?  i processed in pixinsight,and also in astro pixel processor.

some images are   here https://www.astrobin.com/users/kajouman/

most i use sigma klipping,for astro pixel processor i use sara wagner tutorial.

well tips are welcome.
Edited 06 Jun, 2018 20:30
pricech44
07 Jun, 2018 17:39
Images look good. I think you might want to get more exposure time on your images say 300 seconds at a minimum. Always take darks and as many bias files as you can. A good goal on darks is 20 of them. Also take some flats. Most of your issue is not enough exposure for each light file.

Hope this helps
chris
kajouman
08 Jun, 2018 00:26
thanks…..yes the last one is to short. 90 sec each. but other are 180sec each,total 9 hours or more.

but  im trying to get more data, darks and flats  i also use.

do i still need bias with the asi1600 mm ? i did it with a canon dslr, didnt now its needed  for mono too.

thanks anyway
Dennys_T
08 Jun, 2018 00:53
Your images are not too bad at all. To better fight against noise, dont use too high gain with the ASI (lke 150+ i find pics too grainy) Expose a little longer if you can and at temperature of -20. Yes you should still use bias (50) and of course darks, as no sensor is perfect.
HazelLE
08 Jun, 2018 03:49
smile ohn, I would recommend downloading Noiseware Community Edition (free). It was a great help to me  in getting rid of the grain. Good luck!
kajouman
08 Jun, 2018 03:50
thanks… yes i like to use low gain too.  most gain 75. making new darks now,bias  too and see how it work.tryed dithering to tonight could help .
kajouman
08 Jun, 2018 12:43
Lawrence E. Hazel
smile ohn, I would recommend downloading Noiseware Community Edition (free). It was a great help to me  in getting rid of the grain. Good luck!

thanks
HillTop
11 Jun, 2018 16:00
FWIW, I've seen lots of advice against using bias frames with this camera.  I use flat darks myself.
kajouman
11 Jun, 2018 22:37
i can give it a try too,all that can help to make it better is welcome.

ps i read somewhere that  the most programs autmatically do it.

If your stacking program scales darks, it will usually scale them to the flats when calibrating.  If that's the case, you don't need to take
flat darks.  It is already done mathematically using your normal flats
and darks.  PI automatically scales darks to flats.

but ill see.
HillTop
12 Jun, 2018 16:25
Problem is, scaling doesn't work if the bias noise isn't being correctly represented.  But hey, if it works for you, it's all good.
kajouman
12 Jun, 2018 19:51
Greg Trotter
Problem is, scaling doesn't work if the bias noise isn't being correctly represented.  But hey, if it works for you, it's all good.

i just swa this on cloudynights..i didnt tryed it myself.

soon as the weather will be good.ill try
 
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