design8r Posted April 15, 2005 Share Posted April 15, 2005 As i'm relatively new to photography you will excuse the following question... How is the button near the buttom of the lens which is the DOF preview used? When it is pressed the viewfinder goes darker... thx Link to comment Share on other sites More sharing options...
phule Posted April 15, 2005 Share Posted April 15, 2005 It stops the lens down to the aperture you've set in the camera. The best way to see what it's doing is to start with the lens wide open and the camera on a tripod. Focus on a subject close to you and hold the DOF Preview button down. With the preview button depressed and held, decrease the aperture one value at a time. Watch how the DOF increases. It's like squinting but for your camera. Link to comment Share on other sites More sharing options...
phule Posted April 15, 2005 Share Posted April 15, 2005 B.t.w. see also page 85 of your user manual. Link to comment Share on other sites More sharing options...
dave_trayers Posted April 15, 2005 Share Posted April 15, 2005 Or you can read online: <p> <a href="http://photonotes.org/cgi-bin/entry.pl?id=Depthoffieldpreview">http://photonotes.org/cgi-bin/entry.pl?id=Depthoffieldpreview</a> Link to comment Share on other sites More sharing options...
dogbert Posted April 15, 2005 Share Posted April 15, 2005 As Rob has said the DoF preview button stops the lens down to the aperture you have set, which is why it goes darker. As the viewfinder is looking through the lens and the lens is now stopped down, what you see is what you will be getting. With the 350D tiny viewfinder it may not be much help except in very bright light. DoF preview is probably of more value in cameras with better/bigger viewfinders. Link to comment Share on other sites More sharing options...
dogbert Posted April 15, 2005 Share Posted April 15, 2005 As you have made decent investment in a very good camera, a good book on slr photography might be an idea. Link to comment Share on other sites More sharing options...
taner Posted April 15, 2005 Share Posted April 15, 2005 Give your eye some time to adjust to the lower light level at the stop-down aperture. Most manual focus 35mm cameras have a mechanical DOF preview which you might use to stop down in degrees - the more you press the button the more you stop down. You can sort of do this with an electronic viewfinder by stopping down gradually (in aperture priority mode turn your dial, say from f/4 to f/16) while you are still pressing the DOF preview button (at your own risk of course). This method helps me. Link to comment Share on other sites More sharing options...
taner Posted April 15, 2005 Share Posted April 15, 2005 350D's viewfinder is pretty bad and tiny (I have the same camera), and judging critical DOF with it is kind of like playing the lottery... Link to comment Share on other sites More sharing options...
design8r Posted April 16, 2005 Author Share Posted April 16, 2005 I understand what DOF preview does...i just cannot see circumstances when it will be used...does anyone here actually ever use it? if yes in which occasion? thnks Link to comment Share on other sites More sharing options...
bob jr. Posted April 16, 2005 Share Posted April 16, 2005 kp, it supposedly makes it so more things in the picture are in focus. the nine-point focus system finds the closest and farthest objects, then "stops down" or closes the aperture some to achieve the more-in-focus effect. Link to comment Share on other sites More sharing options...
taner Posted April 16, 2005 Share Posted April 16, 2005 Graduated ND filters would be one use - when you are sliding them lower in the holder, the stopped down viewfinder makes it easier for you to see where the transition on the filter starts so you can position it accordingly in the shot. More so with one or two stop filters than with 3 or 4 stop filters - I can use 3 stop (0.9) GND transition area with my f/2.8 or faster lenses wide open. Link to comment Share on other sites More sharing options...
dogbert Posted April 16, 2005 Share Posted April 16, 2005 I use it as well as a check for some compositions when I want both background and foreground elements in focus. Link to comment Share on other sites More sharing options...
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