ISO, and You?

Annika Backstrom
in misc, on 31 December 2003 (history)

After several nights of shooting with my Nikon

Coolpix 4500 I started to notice a trend in low-light situations:

there seemed to be a high amount of noise in many of the pictures.

A quick look at the manual showed that this is a known problem

during extended exposures, but it turns out the ISO

setting has a lot to do with noise as well. Digital Photography Review has a good explanation of why this happens.

I took some sample images to compare noise at four ISO settings:

ISO 100, ISO 200, ISO 400, and ISO 800. These shots used automatic

sharpening, automatic contrast, and incandescent white balance

adjustment. ISO, exposure time, and noise reduction (NR) state are

shown below the image.

![Sample image at ISO 100.][] ISO 100, 0.71s NR off
![Sample image at ISO 200.][] ISO 200, 1/3s NR off
![Sample image at ISO 100.][1] ISO 400, 1/6s NR off
![Sample image at ISO 100.][2] ISO 800, 1/12s NR off

Ever-increasing amounts of noise can be seen as we move from ISO 100 to ISO 800. Quality on ISO 200 is acceptable to my eyes, with slight amounts of noise visible in areas of solid color.

For comparison, I reshot ISO 100 and ISO 200 with noise reduction

enabled. ISO 400 and ISO 800 were shot at faster than 1/4s, which

automatically disables NR.

![Sample image at ISO 100 with noise reduction.][Sample image at ISO 100.] ISO 100, 0.77s NR on
![Sample image at ISO 200 with noise reduction.][Sample image at ISO 100.] ISO 200, 1/3s NR on

Both shots appear identical to the ISO 100 image with NR disabled. Looks like I'll be relying on long exposure times instead of unnaturally high ISO settings. (Initial testing shows that a high ISO is much more damaging than a long exposure time. I can shoot an 8" exposure without noticible noise.)