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Noise

ashenlight

By ashenlight
in Imaging - Discussion

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ashenlight

ashenlight

Posted
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A simple question which I am sure will yield very informative answers....

How does one reduce noise in images? I ask because I am about to rush into an attempt to do some widefield astro photos. Once I up the ISO I'm sure the photos (do we call these 'subs'?) will suffer from noise... what can I do to remedy this?

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Aza

Aza

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Ideally you want to take many subs of the same target.

Then stack them all up with software.

By doing this you increase the SNR, which is the signal to noise ratio.

For best results though you need to be shooting in RAW format, rather than jpeg.

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blinky

blinky

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As the others have said but you also get some noise reduction plugins for Photoshop. I usually run Neatimage after final processing to remoe any residual noise. THe most important thing is to take loads of subs though.

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brianb

brianb

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You could also take a dark frame and then remove the noise in the post processing...

That helps with repeatable noise sources (amp glow) but not with quantum noise - the only cure for quantum noise is is increase the number of photons detected. Don't use a very high ISO setting. Shoot in raw mode, set the ISO to about 400, take lots & lots of subs (making the exposure for each sub as long as the tracking and/or light pollution will allow) & stack them in Deep Sky Stacker.

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Aza

Aza

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I pretty much learnt everything I know from this forum!

So you are are definitely at the right place.

Just beware that it is a slippery slope.

Once you get a taste you keep wanting to move up a level!

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James

James

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Careful Amanda, imaging is a dangerous addiction that snared me last autumn. To give an idea of the danger I'd been a fairly rabid visual only observer for over 20 years and have sworn that I'd never image - there's probably posts of mine saying that. :)

How wrong I was :headbang:

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SteveL

SteveL

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Kelling was great last Sept, it was the transformation of James. "Oh I wont get pulled in, i am a visual observer only, dont want to dabble in the dark side, wont be interested, blah blah blah"... then that first sub of NGC7331 popped out and onto the screen. You were standing behind Steve (FLO) and Michael (SX), hoping that no one would notice that you were lighting up the field with that wide grin you had.... oh yes, we noticed...

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ashenlight

ashenlight

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Hahahaha Steve that is a brilliant story, poor James lol! I am smiling like an idiot at the mental image of that.

You should be encouraging this James I may buy my first CCD from FLO in a year or so, you never know :) Out of interest, why did you swear you'd never image? Was it because you knew what a slippery slope it was?

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James

James

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It's a long story really and I'll spare everyone the details (for now :) ) but ironically the reasons I didn't want to image turned out to be pretty much the reasons that I ended up wanting to image, sort of.

It is a slippery slope...

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Psychobilly

Psychobilly

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Imaging will show you things that the MK1 eyeball never will... and whilst there are Zillions of brilliant images all over the WWW there's nothing quite like capturing and processing the image yourself... probably similar to teh experience of "glimpsing" a faint fuzzy blob with the Mk1 EB... but as the sig says....

Imagers do it in Glorious TECHNICOLOR or Narrowband...:)

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ashenlight

ashenlight

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James, I will have to get that story out of you at SGL5 :headbang: perhaps we may need to beer induce you first? :)

Yea Peter, can't imagine the pride and joy brought about by seeing your very own image appear on the screen, after all the time capturing, processing... must be such a thrill :) I have made it my mission to capture M42 come the winter. Even if it's in an Orion widefield....

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Ant

Ant

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Kelling was great last Sept, it was the transformation of James. "Oh I wont get pulled in, i am a visual observer only, dont want to dabble in the dark side, wont be interested, blah blah blah"... then that first sub of NGC7331 popped out and onto the screen. You were standing behind Steve (FLO) and Michael (SX), hoping that no one would notice that you were lighting up the field with that wide grin you had.... oh yes, we noticed...

I also remember that clearly, I'd just finished talking to grant and happened to walk past James et al. Beaming from ear to ear as I recall!!!!

It is a slippery slope, but it's a fun slope!

Ant

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samtheeagle

samtheeagle

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I have made it my mission to capture M42 come the winter. Even if it's in an Orion widefield....

Ditto :)

I'm still very new to imaging, but I can see why visual observers consider it to be the dark side. I've spent hours outside with my scope, and not really looked at anything once I had lined up for the shot. I must admit that I do sit there waiting for the subs to stack up thinking "what the hell am I doing here?". But once you get all the data on to the computer and you see the image coming together it's a real buzz!

That's said I'm hoping to remain a 50/50 type, I still love just looking at stuff. There's more of a connection when you are actually seeing something first hand, even if it is small, fuzzy, devoid of colour information :headbang:

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