SAMPLE IMAGES AT VARIOUS ISO NUMBERS
Why not get your D2x and manual, and we'll look over the ISO and Noise Reduction settings. Even if you think you understand ISO and NR settings, this will be a good review, and you might even learn something. ISO is covered on pages 52 and 53 of the D2x manual.
Here, in Figure 1, is the image I am using as a test image for all the illustrations below. I took a picture of the D2x logo on the edge of the D2x camera box, using my D2x and an AF 60mm Micro Nikkor lens. The small red rectangle is the actual area of the picture we'll examine in the other images below to see the ISO sensitivity noise changes:
Next, we'll look closely at images from the D2x at various ISO settings. In Figure 2 below, examine the images taken with the D2x and an AF Micro Nikkor 60mm lens. This is the same subject, as seen in Figure 1 above, and the images are at 100% cutout with no post processing applied. All RAW file to JPEG conversions were done using Photoshop CS ACR.
To save web space the images in Figure 2 below reflect full 1 EV steps from 100-3200 ISO. This will allow you to judge the noise levels from increasing the ISO, with no additional noise reduction applied. Basic noise reduction is always applied to HI-1 and Hi-2 settings, even if you have noise reduction turned off in your D2x. If you turn noise reduction ON, then even more than “normal” will be applied to the HI-1 and HI-2 settings.
Here, in Figure 3, is a full frame JPEG view of an image at 100 ISO, and the same image at 3200 ISO (HI-2) with no noise reduction.
In examining the two images in Figure 3, the JPEG compression tends to smooth the apparent differences. But, surprisingly the differences aren't that great. The colors are more muted in the HI-2 image, and somewhat grainier, but much less so than equivalent film images would be.