steve_stoneblossom Loc: Rhode Island, USA

I currently use Nikon D700. For the life of me, I do not find the depth of field preview button does anything other than dim what I see in my viewfinder (more with smaller apertures, less with wider ones). Am I doing something wrong?

Wabbit Loc: Arizona Desert

No you're not, they are hard to decipher. What you can see is the visible depth of field that will be in focus.

With my old manual focus lenses I was able to easily see what my depth of field should be by glancing at the distance scale on my lens in conjunction with my chosen aperture. Ah the good old days, was so simple then.

MT Shooter Loc: Montana

The depth of field preview button simply sets the aperture blades to the setting that your camera is going to take the shot at. The aperture is wide open when focusing and metering to allow for maximun light to pass through the lens into the camera. When the shutter is pressed the aperture blades snap to the shooting position and the shutter curtain trips (amongst other actions) to capture the image. Your viewfinder will always dim unless you are taking the shot with your lens wide open. When you press the DOF preview button you are simply looking through the narrowed aperture and seeing exactly what the sensor will see when the shutter trips.

steve_stoneblossom Loc: Rhode Island, USA

OK, so then I misunderstood the function. I expected the scene in the viewfinder to mimic what the shot would look like, i.e. out of focus foreground and background.

MT Shooter Loc: Montana

Thats essentially what it does, but since your eye sees in 3D and the film (sensor) sees in 2D, its hard to retrain your eye to see the actual focal range. I used to see it years ago, but my eyesight doesn't pick it up anymore, so I never use it and depend more on my familiarity of the depth of field of my lenses and shoot in Aperture Priority mode 80% of the time.

steve_stoneblossom Loc: Rhode Island, USA

[/quote]

Thats essentially what it does, but since your eye sees in 3D and the film (sensor) sees in 2D, its hard to retrain your eye to see the actual focal range. I used to see it years ago, but my eyesight doesn't pick it up anymore, so I never use it and depend more on my familiarity of the depth of field of my lenses and shoot in Aperture Priority mode 80% of the time.[/quote]

Thanks once again.

Patw28 Loc: PORT JERVIS, NY

Well, you're lucky with a D700. Hyper focal distance in feet is the square of focal length of your lens in mm. e.g. 50mm squared is 2500. Move the decimal two places to the left for h=25 feet. 100mm > 100 feet. 30mm > 9 feet. 25mm > 6 feet.

I forget if this assumes a coc of 2 or 3 but the results are as good as most of us can apply them (estimate distance).

These are good approximations for field work.