I have talked about depth of field and using aperture to minimize or maximize depth of field in the past. Today I will talk about Automatic Depth of Field function some camera’s have and depth of field preview.
Automatic Depth of Field (A-Dep or DEP) is creative mode on some camera’s that will help you select the best aperture to get everything in your frame in focus. To use A-DEP, turn the dial on your camera to A-DEP, and compose your image. The camera will then evaluate your frame, set your aperture and focus on a point where everything from front to back will be in focus by setting the focus to the hyperfocal distance. As it is an automatic setting, it tends to be hit and miss at time. When using this setting, be sure to have everything you want in focus to fall within your camera’s focus points as this is what the camera uses to determine what needs to be in focus. On older cameras (DEP) you were able to focus on the point nearest to you that you wanted in focus the press the shutter 1/2 way. Next, focus on the point (without changing the zoom setting) further from you and press the shutter 1/2 way. Finally, recompose your photo and press the shutter all the way. The camera will then focus at the correct spot to get the near and far points in focus.
If you want a more manual approach, using your depth of field preview button will help you determine how your given aperture will affect your image. Once your image is composed, press your depth of field preview button to stop down the lens. This will force your diaphragm blades to close and you will be able to see how the depth of field will be represented when you take the photo. Because you are closing the diaphragm blades, the image will go darker in your viewfinder as you let less light into the lens. This is normal and will not alter your image.
Until next time, happy shooting.
My Canon XTi has an A-DEP setting but I haven’t needed to use it enough that I trust it.
The few times I’ve tried it, I’ve been surprised that it didn’t choose a smaller f-stop and slower shutter. So as soon as it took the shot, I’d change the settings to manual and boost the f-stop to be more sure that everything in the 11 focus points was sharp. I just can’t remember what the final outcome was – A-DEP vs manual settings.
Maybe I was wrong and the different parts of the shot weren’t as far apart as I thought? Or did the camera get it wrong? Wish I could remember!