Nikon Understanding Auto Distortion Control for Improved Image Quality

258 David Busch’s Nikon D7000 Guide to Digital SLR Photography

Auto Distortion Control

This option can correct barrel distortion (outward bowing of lines that should be straight) that sometimes occurs with telephoto lenses, and pin-cushion distortion (lines that curve inwards, towards the center of the frame) that can appear when using wide- angle lenses. When turned on, the D7000 uses information about your Nikon-brand lens that is stored in the third (L) firmware module (and which can be updated with new firmware releases as lenses are introduced). Because this correction can result in cropping out part of your image, you may want to turn it off and use it only if you find the distortion produced by your lens is particularly bad.

Nikon recommends using this feature only with type G and D lenses (that is, lenses that have those designations as part of their names). Auto Distortion Control operates as you take the picture; you can also apply distortion control after a picture is taken using the Retouch menu (discussed in Chapter 10). Barrel and pincushion distortion can also be fully or partially corrected using an image editor like Photoshop. The in-camera fea- ture is faster when you have lots of photos to process, because it performs its magic as the photo is saved to your memory card. You’ll find more information about the L firmware module in Chapter 14.

Color Space

The Nikon D7000’s Color Space option gives you two different color spaces (also called color gamuts), named Adobe RGB (because it was developed by Adobe Systems in 1998), and sRGB (supposedly because it is the standard RGB color space). These two color gamuts define a specific set of colors that can be applied to the images your D7000 captures.

You’re probably surprised that the Nikon D7000 doesn’t automatically capture all the colors we see. Unfortunately, that’s impossible because of the limitations of the sensor and the filters used to capture the fundamental red, green, and blue colors, as well as that of the phosphors used to display those colors on your camera and computer mon- itors. Nor is it possible to print every color our eyes detect, because the inks or pigments used don’t absorb and reflect colors perfectly.

On the other hand, the D7000 does capture quite a few more colors than we need. Even if you use 12-bit capture instead of the default 14-bit capture, an original 12-bit RAW image contains a possible 68 billion different hues, which are condensed down to a mere

16.8million possible colors when converted to a 24-bit (eight bits per channel) image. While 16.8 million colors may seem like a lot, it’s a small subset of 68 billion captured, and an even smaller subset of all the possible colors we can see.

The set of colors, or gamut, that can be reproduced or captured by a given device (scanner, digital camera, monitor, printer, or some other piece of equipment) is repre- sented as a color space that exists within the larger full range of colors. That full range