# Which is the lesser evil ? Under exposed vs High ISO noise



## Kolia (Jul 21, 2012)

I'm curious what you guys think.

I'm using Lightroom 4, my camera gets rather noisy past 1600 ISO.

What would give better results in low light situation:  



Under exposing -1.0EV at 1600 ISO and correcting the exposure in LR
Correct exposure at 3200 ISO and dealing with the noise in LR


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## Overread (Jul 21, 2012)

You will nearly always get less noise at a higher ISO and exposing correctly for the shot, than you will if you underexpose and then bump up the brightness in editing after at a lower ISO. Even at the high ISO values this remains true; thus whilst you can correct for underexposure, you'll still get better results exposing correctly. 

I would also recommend looking up the method "expose to the right" which is an exposure theory that can help in situations where you've the option to use it. It is theory and thus, in the real world, is something that you might not be able to use in every situation, but which when you have the chance can give you more to work with in your digital files. 

I would also suggest reading up on methods for noise removal and sharpening; these methods can be a little more involved, but can result in much more improved results at your final output medium.


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## jake337 (Jul 21, 2012)

Proper exposure and expose to the right come to mind.

Shot, accidentally at 3200 with flash.


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## MTVision (Jul 21, 2012)

Kolia said:
			
		

> I'm curious what you guys think.
> 
> I'm using Lightroom 4, my camera gets rather noisy past 1600 ISO.
> 
> ...



You'll probably get a noisier image by under exposing at ISO 1600 and raising exposure in post then you would by exposing properly at ISO 3200. Anytime you underexpose (even at ISO 100) and raise exposure in post you introduce noise. Always better to expose properly or ETTR (expose to the right).


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## fjrabon (Jul 21, 2012)

The only times you should ever purposefully underexpose are these two scenarios:

1) Your ISO and aperture are maxed out, and slowing down the shutter speed any more will result in a blurry image.  I occasionally have this happen in concert photography in dimly lit bars.  Dealing with noise is better than dealing with blurry pictures.  

2) When you want to preserve a highlight with detail that would otherwise blow out, if you exposed for the main part of the scene correctly, and HDR isn't an option for whatever reason.


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## Compaq (Jul 21, 2012)

Quick test. Notice the noise, as well as shadow detail.

Canon EOS 40D, Tokina 11-16mm @ f/2.8

0EV @ ISO-3200 (ISO-high setting)





100% crops










-1EV @ ISO-1600





100% crops


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## Kolia (Jul 21, 2012)

Thanks, 

That was a clear cut answer !


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## KmH (Jul 21, 2012)

Gaining a solid, fundamental understanding of how digital images work would shed light on digital image exposure mysteries.

http://wwwimages.adobe.com/www.adob...ly/prophotographer/pdfs/pscs3_renderprint.pdf
http://wwwimages.adobe.com/www.adob...e/en/products/photoshop/pdfs/linear_gamma.pdf


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## Garbz (Jul 22, 2012)

I've posted another quite detailed example of this from a D200 here: http://www.thephotoforum.com/forum/beyond-basics/221509-noise-iso-push-vs-pp-push.html#post2052761

Conclusion, always up the ISO. The ISO does more than simply playing with software. The bias of sensors and the ADC changes making the camera physically more sensitive. Up the ISO, if not for the better noise performance than for the fact that you don't lose shadow detail when you do this.


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## KmH (Jul 22, 2012)

ADC = Analog to Digital Converter. The heart of your digital camera, the image sensor, is an analog device, not a digital device.


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