What exactly does the Depth of Feild Preview do? :dunno Do people use it? It just seems to make the picture a little darker for me, I don't notice any change in depth of feild.
Thanks
I'll assume you're somewhat familiar with how DOF works... the preview button closes down your aperture to the F-stop you have set (thats why it gets darker). It also takes a second for your eyes to adjust. Go out on a nice day, compose a scene with some depth, set it to F10, hit preview and give it at least 5 seconds... if you don't see a difference, get your eyes checked!
Its a handy tool for landscape work, I also find it useful for macro work when the depth is small.
Basically just that. Like Eric said, it stops the lens down to your selected aperture (remember that it's wide open until you actually take the picture). So DOF preview is showing you what the "film" will actually see when the shutter is tripped. Again, like Eric, I usually use it for landscape or macro work where I want to be sure of where the DOF is & what's out of focus.
The DOF Preview button really comes into its own when you mount the camera on a tripod, that optical accessory that sharpens all your lenses:D
Then, you can critically examine the viewfinder window image, and study the DOF, after pressing the DOF preview button for 15-20 seconds to let your eye dark adapt a bit. Using the DOF Preview button handheld can be challenging.
Just a bit more in the way of explination in case you're still confused:
When you take a photo, no matter what aperture you set your camera to, it keep the aperture at it's widest setting so you can focus with lots of light, then only closes it down to you chosen setting at the last second when you take the photo. That means that normally, even if you set the camera to F22, when you look through the viewfinder your DoF will be very shallow. When you hit the DoF preview, as mentioned above, it actually closes down the aperture while you're still looking, so you can see what will really be in focus in your shot.
An example: I just looked through my 200mm lens at a water bottle sitting on my table. I focused on the water bottle, and the background looked out of focus, even with the lens stopped down to F22. Then I hit the DoF preview button, waited for my eyes to adjust, and saw that if I were to really take a photo at that setting, the background would have been in focus as well as the bottle. Hope that helps,
A long time ago, before lenses for Single Lens Reflex cameras were all automatic aperture, you focused the lens manually with the aperture ring turned so it was wide open - the iris diaphragm was not closed at all. Then, when you were ready to press the shutter, you pressed a button or turned a ring to cause the iris aperture to close down to the chosen f stop. And then after the exposure, you had to reopen the iris diaphragm again ...This was in addition to focusing manually also
The DOF preview button is just doing what all SLR shooters had to do prior to the 1960's or so
The old Practika and Exacta SLRs were mostly like this if memory serves.
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Its a handy tool for landscape work, I also find it useful for macro work when the depth is small.
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http://www.chrislaudermilkphoto.com/
Then, you can critically examine the viewfinder window image, and study the DOF, after pressing the DOF preview button for 15-20 seconds to let your eye dark adapt a bit. Using the DOF Preview button handheld can be challenging.
Moderator of the Technique Forum and Finishing School on Dgrin
When you take a photo, no matter what aperture you set your camera to, it keep the aperture at it's widest setting so you can focus with lots of light, then only closes it down to you chosen setting at the last second when you take the photo. That means that normally, even if you set the camera to F22, when you look through the viewfinder your DoF will be very shallow. When you hit the DoF preview, as mentioned above, it actually closes down the aperture while you're still looking, so you can see what will really be in focus in your shot.
An example: I just looked through my 200mm lens at a water bottle sitting on my table. I focused on the water bottle, and the background looked out of focus, even with the lens stopped down to F22. Then I hit the DoF preview button, waited for my eyes to adjust, and saw that if I were to really take a photo at that setting, the background would have been in focus as well as the bottle. Hope that helps,
Fred.
http://esiggins.smugmug.com
The DOF preview button is just doing what all SLR shooters had to do prior to the 1960's or so
The old Practika and Exacta SLRs were mostly like this if memory serves.
Moderator of the Technique Forum and Finishing School on Dgrin