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Author Topic: Managing Noise ?  (Read 1319 times)
FrankG
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« on: March 13, 2013, 06:11:15 PM »
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I have started using a small pocketable camera (Sony RX100) as my 'carry everywhere' camera and shooting RAW files to allow me the possibility of max quality.

It exhibits quite a lot of noise for my taste (small 1" sensor). Very noticeable 'cos I'm often on a slow-ish shutter speed and soft/dim light. Even though I try to limit my iso to a max of 400. It's particularly, a problem when enlarging for a big print.

Is noise reduction best dealt with :
1. in camera
2. in RAW conversion (I have ACR with the sliders for Luminance & Color)
3. in Photoshop (the Noise reduction filter)
4. (I'm not keen to buy a 3rd party plug-in)

Thanks
(p.s. i had this posted on another forum but I think this is a more suitable venue)
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Slobodan Blagojevic
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« Reply #1 on: March 13, 2013, 06:23:16 PM »
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Your best bet would be giving enough light to the shadows, i.e., exposing to the right (ETTR), followed by ACR noise reduction.

Also, limiting yourself to 400 ISO is not the best idea either. You should check out Andrew Rodney's (aka digitaldog) example of 800 ISO being better than 100 ISO. The thread about it is here.
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Slobodan

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FrankG
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« Reply #2 on: March 13, 2013, 06:43:30 PM »
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Your best bet would be giving enough light to the shadows, i.e., exposing to the right (ETTR), followed by ACR noise reduction.

Also, limiting yourself to 400 ISO is not the best idea either. You should check out Andrew Rodney's (aka digitaldog) example of 800 ISO being better than 100 ISO. The thread about it is here.


Thanks for this. I have perhaps done the wrong thing by trying to always limit my iso to 400, thinking it would help reduce noise.
That link is "crazy" I have to go back and read it again, and again.
At first it doesn't make complete sense to me.

I understand increasing noise if you are under-exposed (because of low light level and low iso). But if my image is correctly exposed, and still exhibits noise at a low iso, then what is it - small sensor, sensor heat build up, slow shutter speed,  ...?

But re: managing noise - your advice is to do it in ACR. Good, thanks.
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Slobodan Blagojevic
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« Reply #3 on: March 13, 2013, 07:13:29 PM »
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... But if my image is correctly exposed, and still exhibits noise at a low iso, then what is it...

The image might be correctly exposed as a whole, but still underexposed in the shadows. So there are only two options for that: either ETTR or multiple exposures (if you risk clipping highlights with ETTR). Or use a bigger sensor, or cameras with better dynamic range (e.g., certain Nikons and Pentaxes).

On the other hand, the fear of noise is overrated... a little bit of it might actually help the appearance of sharpness and avoidance of that "plastic digital look." For examples how noise can impact sharpness, see this (scroll to the bottom, wall images)
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Slobodan

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Vladimirovich
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« Reply #4 on: March 13, 2013, 08:38:53 PM »
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But if my image is correctly exposed

start with the question = how do you know that your raw image was actually correctly exposed ? if you are shooting raw - download rawdigger from http://www.rawdigger.com

and read some articles @ http://www.rawdigger.com/howtouse
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FrankG
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« Reply #5 on: March 13, 2013, 08:50:39 PM »
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My concept of a correctly exposed image is one that needs no further exposure correction or modification.
Like a well exposed transparency (for those who remember film) that doesn't need an 1/2 stop over or under - it's just right.
Had it been under-exposed (to the left) and needed 'opening' up I'd understand.

I guess I'm going to have to learn to live with noise on this RX100 camera (I have a 5D2 for when I want a noiseless result & situations where the bulk doesn't matter).

After reading Michaels review on the main site I expected less noise. Now reading it again I see he does say to use ACR 's noise reduction.
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Slobodan Blagojevic
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« Reply #6 on: March 13, 2013, 09:05:47 PM »
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It might be useful to post examples of what you consider excessive noise (both whole scene and a 100% crop).

I suspect that if you are exposing for what's "just right" for a transparency film, you might be underexposing in digital terms, i.e., not ETTR-ing.  
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Slobodan

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David Sutton
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« Reply #7 on: March 13, 2013, 09:06:35 PM »
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My concept of a correctly exposed image is one that needs no further exposure correction or modification.
Like a well exposed transparency (for those who remember film) that doesn't need an 1/2 stop over or under - it's just right.
Had it been under-exposed (to the left) and needed 'opening' up I'd understand.

I guess I'm going to have to learn to live with noise on this RX100 camera (I have a 5D2 for when I want a noiseless result & situations where the bulk doesn't matter).

After reading Michaels review on the main site I expected less noise. Now reading it again I see he does say to use ACR 's noise reduction.


From what you are describing your images are NOT correctly exposed. Digital is quite different to film. If your histogram is not covering the full range and you want less noise in the shadows, then expose to the right (ETTR). Remember it's raw data, the final exposure is not set until you do the raw conversion. Most often the software will do the adjusting to a "correct" exposure "under the bonnet" (or "hood" if from Nth America)
If you don't want to buy a 3rd party plug in for Photoshop, then try converting the file to lab and apply a blur to the a or b channels, pick the one with the most noise.

Edit: Ha! You got in first Slobodan
« Last Edit: March 13, 2013, 09:08:41 PM by David Sutton » Logged

FrankG
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« Reply #8 on: March 13, 2013, 09:26:26 PM »
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I never did get my head wrapped around this ETTR thing (getting the histogram to touch the right) and then Always having to bring the Exposure slider in ACR back down to the left to reduce what looks overexposed to what looks good

I think I've learned a few things here tonight:
1. dont be afraid of some noise it can even enhance the appearance of sharpness
2. don't be afraid of high iso as it doesn't necessarily mean more noise
3. consider multi imaging as a technique -
see here http://www.cambridgeincolour.com/tutorials/image-averaging-noise.htm
and the RX100 has that mode built in to do it in-camera (with jpeg only though)
4. Over-expose a little (ETTR)

btw this little camera also has Dynamic Range Optimizer built in as a menu option with values from 1-5 (1 looks good with detail in highlights & shadows but still 'normal' , 5 looks flat like way too little contrast. Not as fake as hdr but along those lines. that's another sory.

Thanks everyone.
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