Photography Lab #1: Examining ISO and Noise Reduction

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What’s the effect of ISO on a shot? And how do we get rid of that pesky noise when we jack up the ISO to get that low light shot? Today I set out with my Sony NEX-5 and tripod to find out. Check the captions for tech details and click to enlarge (remember, these are SCREEN SHOTS, not actual photos).

Here’s an unedited 6400 ISO shot of my family room with lots of detail. Notice the noise in this shot (check out the far light green wall near the ceiling, for instance):

Exhibit A: Unedited Shot: ISO 6400, 18mm, 1/13 sec @ f22 mounted on tripod

Exhibit A: Unedited Shot: ISO 6400, 18mm, 1/13 sec @ f22 mounted on tripod

For comparison’s sake, here’s the same shot at ISO 100. Much cleaner, yes?

Exhibit B: Unedited Shot: ISO 100, 18mm, 5.0 sec @ f22 mounted on tripod

Exhibit B: Unedited Shot: ISO 100, 18mm, 5.0 sec @ f22 mounted on tripod

Now, here’s where it gets really interesting. Using Adobe Lightroom, I zoomed in (4:1) on an area of detail (lettering just above the fireplace and to the right of the white lamp shade) and took a screen shot. This is a pretty extreme level of zoom, but I’m trying to prove a point here. This is the zoomed screen shot of the 100 ISO image. Not too shabby, eh? You can pretty much make out the letters. Merry Christmas.

ISO 100, 18mm, 5.0 sec @ f22 with NO noise reduction

ISO 100, 18mm, 5.0 sec @ f22 with NO noise reduction

Now the zoomed screen shot of the 6400 ISO image. No bueno. Noise. Lots of it. You can still barely make out letters, but it hurts the eye to do so. Again, an extreme close up, but this is what’s happening in the photo.

ISO 6400, 18mm, 1/13 sec @ f22 with NO noise reduction

ISO 6400, 18mm, 1/13 sec @ f22 with NO noise reduction

Now we go to work in Lightroom. Using Noise Reduction, I made a few adjustments and here’s the result. Not perfect, but much closer to the 100 ISO image and much less annoying to look at.

ISO 6400, 18mm, 1/13 sec @ f22 WITH noise reduction

ISO 6400, 18mm, 1/13 sec @ f22 WITH noise reduction

And, finally, here’s the full version of the NR corrected shot at 6400 ISO. Compare with the first photo in the article. Much cleaner.

Exhibit C: EDITED (NR) Shot: ISO 6400, 18mm, 1/13 sec @ f22 mounted on tripod

Exhibit C: EDITED (NR) Shot: ISO 6400, 18mm, 1/13 sec @ f22 mounted on tripod

For those with Lightroom, here are the settings of the edited photo:

Sharpening
Amount: 37
Radius: 2.3
Detail: 34
Masking: 24

Noise Reduction
Luminance: 34
Detail: 79
Contrast: 100
Color: 20
Detail: 34
Smoothness: 46

For more on ISO and Noise, check out this article: http://www.slrlounge.com/school/how-iso-affects-your-images

Or this one: http://digital-photography-school.com/iso-settings