[jensp2m]

Hi. I'm new to photography and looking at a few different cameras. What is DOF preview and how do you use it? This is one of the options I'm comparing. Thanks!

[MrApollinax]

By using hte DOF preview you get to see how your aperture settings effec Depth of Field without having to take a shot and then look at it after it is written to your memory card. It is quicker than taking a shot looking at it, deleting it and adjusting it as you need.

[Peter Zack]

(Depth Of Field) DOF preview is used to 'stop the lens down' before taking a picture. Aperture is the variable opening inside the lens that controls light transmission and DOF.

The lens is (assuming a modern automatic lens) always focused wide open so the viewfinder is nice and bright and the focus lock is fast. So if you were to select f8 on an f1.4 lens, the camera will meter the scene with the lens wide open (at f1.4) but calculate what the meter reading is for f8. The lens only stops down mechanically to f8 during the split second the shutter button is pressed. If it didn't work this way, focus would be slow or not at all and the viewfinder would be too dark to see through. But the problem is, you can't tell what the effect of an f8 setting is on the DOF because the lens is always wide open.

So on a Pentax the DOF preview is a lever that allows you to stop the lens down to your selected aperture setting so you can see the effect of the aperture on the DOF. Great tool especially in creative photography and macro shots.

[clmonk]

Great answer, Peter! Succinct but sufficient!

[Marc Sabatella]

As far as I'm concerned, actually getting a DOF preview is not all that important to me - given that the viewfinder darkens, and it' not *100%* accurate anyhow (the focus screen alters things in some case), I'd just as soon take the picture and look at the LCD.

However, I consider DOF preview an indispensible feature on a Pentax DSLR anyhow, because it happens to be the only way to get the camera to display the meter reading with a manual exposure lens. You can press a button to get the camera to set an appropriate shutter speed for you, but I prefer actually *seeing* the meter reading in the viewfinder, and that only happens while doing a DOF preview.

Not an issue if you don't use manual lenses often, or if you're comfortable with the "semi-automatic" exposure mode of pressing a button to set shutter speed (eg, if you normally use Av mode with modern lenses). But for someone who really uses manual lenses and manual exposure modes a lot, a Pentax camera without DOF preview is pretty severely crippled. For other camera brands, there may be other issues; DOF preview may have nothing to do with metering. So what I'm saying only applies when comapring pentax DSLR's.