how to get less noise or grain - Forums

Topic starter

Jun 6, 2018 · Edited: Jun 6, 2018

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.

Chris Price

Jun 7, 2018

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

Helpful

John

Topic starter

Jun 7, 2018

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

Jun 7, 2018

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.

Concise

Lawrence E. Hazel

Jun 8, 2018

ohn, I would recommend downloading Noiseware Community Edition (free). It was a great help to me in getting rid of the grain. Good luck!

Concise

John

Topic starter

Jun 8, 2018

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 .

John

Topic starter

Jun 8, 2018

Lawrence E. Hazel:
8) 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

Greg Trotter

Jun 11, 2018

FWIW, I've seen lots of advice against using bias frames with this camera. I use flat darks myself.

John

Topic starter

Jun 11, 2018

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.

Greg Trotter

Jun 12, 2018

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.

John

Topic starter

Jun 12, 2018

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

John

Topic starter

Jul 6, 2018

John:
Lawrence E. Hazel:
8) 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

thanks...and yes,great tool.
i used it on this one.
https://www.astrobin.com/354314/0/?real=&nc=user