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May 21, 2002

Depth of Field Preview

Alan wondered why the Nikon N80 has a 'depth of field preview' button. It's an SLR, right? You're seeing what the lens is seeing, right? So what do you get with a 'preview' button that you don't get otherwise? So I looked it up. From the Nikon N80/F80 Magic Lantern Guide:

The depth-of-field preview button is located on the front of the camera body under the focus-assist lamp. It can be pressed easily with the middle finger of the right hand. When you do so, the diaphragm mechanism of the lens stops down to the actual aperture you have selected. Instead of viewing the scene at the widest lens aperture, you can do so at f/8, f/11, or f/16, and so on. This enables you to visually assess the actual zone of apparent sharpness that will appear in a photograph.

So when framing a picture through the viewfinder, the lens is actually at its widest aperture, despite your chosen setting. DOF Preview lets you see what you'll be getting when the camera actually exposes the film.

Posted by dpwakefield at May 21, 2002 09:08 AM