Depth of field preview question

Hi, sorry to be a complete beginner, i understand depth of field is the area that is in focus, what does that make the depth of field button, what does it do, ? thank you

As, you increase the f number of the aperture, the depth of field increases, but the camera keeps the aperture open at the maximum aperture to focus and only stops down to your desired aperture just before the picture is taken.

So what you see is not necessarily what you will get.

So the button is to see what would be in focus for a different aperture.

Hope this helps

Well, leaving all the theory aside, what the button does is to stop the lens down to the selected aperture.

In the small viewfinder of a DSLR, it is often difficult to perceive the difference when pressing the DOF preview button, other than noticing the view getting dimmer.

That's been my experience as well - I might have a very shallow DOF, but with the preview button it's really not easy to make it out. I've had that button on my Nikon film camera and now on my Canon digital. The nice thing about digital of course is that even if you can't really get a great grasp of the DOF from using the DOF preview button, you can always just check the LCD after the shot.

Yes indeed. However, IMHO, the DOF preview button is still a useful tool in certain cases. For instance, if you are taking a portrait, you want to blur the background, (but still recognizable, not *too* blurry). In such scenario, you can use DOF preview to choose the most appropriate aperture. I do this a lot.

OK... there is ONE very, very useful function of the depth of field preview button. If you have a flash gun attached to the camera, pushing the DoF preview button causes the flash to strobe at high speed for a couple of seconds. This can be very helpful if you are shooting in a dark location, have dropped a compact flash card or other small item and don't have a flashlight handy.

I find the DOF preview button very helpful. It just takes a little practice and remember its the backround you are concentrating on, not the subject.

I learned something today. I knew nothing about the DOF preview button until now. I was shooting with the 100mm f/2.8 Macro yesterday and wished I had something like that.

I find that I use the DOF button most for macro photography. Depth of field is so limited and changing aperture has such a great effect that being able to look at depth of field is important. You get used to peering into the darkness. Sometimes it takes your eye a few seconds to open up so you can see.

the 350d's viewfinder is rather small thus using DOF preview is not very useful to me.

If I could SEE what was in focus in the viewfinder I wouldn't have gone to AF....

Titus213 wrote:
If I could SEE what was in focus in the viewfinder I wouldn't have gone to AF....

Well yes, that pretty much sums it up. I never use DOF preview, since I soon learned it was too inacurate, the DOF is shallower that the preview, and the OOF areas are much softer.

Same here!
I tried it couple of times, and I do not use it any more..

thank you all for your replies will learn more through practical experience, did help to have the replies