Posts: 310
Joined: Tue Oct 30, 2001 4:31 am

Depth Of Field Preview Button

Mon Apr 26, 2004 3:36 pm


I just got an N80, which features a depth of field preview button

Do you find this feature useful? I just do not know how to process the information i get through the viewfinder when i put the button, the only thing i see is a darker image.

Any help will be very appreciated.

Thank You!
Posts: 1046
Joined: Thu Feb 13, 2003 1:18 pm

RE: Depth Of Field Preview Button

Mon Apr 26, 2004 4:22 pm

You need to actually shot some thing you can see like say a plant (About 3 feet away) in the fore ground and a distance shot like a field.

What you do is set the camera to F-20 then focus like you normally do and press the DOF button. You will see a darker image but the plant and the field will be in focus. You can also see it in some other examples but you will see it more in the above example.
Canon 50D user; 100-400 MM L IS 10-22 MM, 60MM Macro
Posts: 1076
Joined: Sun Jun 03, 2001 6:24 am

RE: Depth Of Field Preview Button

Tue Apr 27, 2004 2:49 am


Since the depth of field is proportional to aperture, pressing the DOF preview button closes the aperture to show the real DOF, but it limits the light, do the image is darker.

For example, if you set an f2.8 lens to f8, the lens still stays wide open at f2.8 until you take the shot, when it momentarily closes to f8. This is so that it can do the autofocus with as much light as possible.

That is why most cameras will not autofocus with lens and converter combinations which push the maximum aperture towards f8 - not enough light.

I used the DOF button more when I was starting out with an SLR - now I have a feel for what aperture to use I don't bother much.

If DOF was critical to a shot, I would take test shots and review them on the LCD screen now that I have changed to a DSLR.

Posts: 1007
Joined: Wed Jan 07, 2004 4:24 am

RE: Depth Of Field Preview Button

Tue Apr 27, 2004 9:49 pm

Is that what that button on the front of the 300D is for? There is that small button at about 4 o'clock (front view) on the side of the bit where the lens gets screwed into. Is that the same? How exactly is it used? Thanks in advance.

I guess that's what happens in the end, you start thinking about the beginning.
Posts: 3879
Joined: Tue Mar 18, 2008 9:21 am

RE: Depth Of Field Preview Button

Tue Apr 27, 2004 10:30 pm

As Craigy wrote, it closes down the aperture to the one that is selected to let you preview how much depth of focus you have.


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