DOF preview (lack of it, actually) was one reason I traded in my MZ-5 for the MZ-5n. Although many seem to find that DOF preview doesn't give the precise effect seen in the final image, and prefer to use distance scales, I find it indispensable.
Is the background in focus, will one stop more or less make it more or less in focus, is it distracting or not? A flick of the switch and a second or two of scrutiny, and I know fairly closely whether I'm using the aperture that's right for the look I want. Also, the area of sharp focus fades gradually into the out-of-focus zone, so that distance scales don't give the true picture, but imply that sharp focus begins and ends at a specific point, which is not the case. With DOF preview, you can move the focus point back and forth to see where the best compromise lies, and that's just one example of its convenience. If DOF preview doesn't suit you, fine, don't use it, but many photographers find it very useful. Pat White
