HowTo: Use The Depth-Of-Field Preview On Your Camera
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DOF preview
button
There is a feature built into all digital SLR cameras that I know of that goes pretty well unused by many photographers. It’s possible that you didn’t even know it existed. If not, you may want to check it out the next time you break out your camera to shoot your next portrait. It’s the depth-of-field preview button, and it’s usually located near where the lens meets the camera body.
The depth-of-field preview (or DOF preview) button allows you to see what the depth-of-field will be for a given aperture before you press the shutter. As a quick refresher for our more novice readers, the wider your aperture (or the lower the number), the more narrow the depth-of-field will be (or the more the background will be blurred).
You see, when you look through your camera’s viewfinder, the lens aperture is wide open, no matter what you set it to. So what you’ll see is the focus point in sharp focus, and everything that’s outside the DOF of fully wide open out of focus. When you press the DOF preview button, the aperture will narrow to the value you set it to, and you’ll see what’s in the DOF and what’s not.
This can be a pretty dandy feature when you’re taking a portrait and you want to throw the background out of focus but make sure that all of the model is in good focus. With a really wide aperture, you can have someone’s eyes in focus and their mouth blurred. If this wasn’t your intention, then the DOF preview tells you quickly. Sure, you could just take a picture and look at the LCD screen, but this can be a lot faster and facilitates you getting set up for the shot quicker.
See It In Action
Here are two photos to give you an idea of what you’ll see. Let’s say you want to take a picture with an aperture setting of f32. This is a very small aperture and should give you a very long DOF, putting lots of things in focus for you. But here’s what you see when looking through the viewfinder:
As you can see, despite the small aperture, the house and fence in the background are well blurred. But with an aperture of f32 they should be pretty sharp. So you press the DOF preview button, and here’s what you see:
Now the house and fence are sharper. Notice that the view got darker. That’s because with the narrower aperture, less light gets in. But you knew that, because you know how exposure works.
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August 15th, 2007 at 8:30 am
Hey Tim
You know, I don’t think I’ve ever used my DOF preview button. O know what it is, and where it is, but never really used it. I generally shoot portraits wide open. If I’m doing studio work it has usually been f/8 on a solid background.
I’m doing a headshot tonight, so I think I’ll give it a crack, just for the geekiness factor. I’ll be in midtown NYC with a lot of stuff in the background. I’ll give it a shot.
Cheers,
Scott
August 15th, 2007 at 9:34 am
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August 15th, 2007 at 11:33 am
Hi Scott. Yep, the DOF button isn’t quite as useful in the studio, since you start to really know your equipment well when you’re in such a defined space that you’re used to. But for outdoor stuff it really comes in handy.
Let us know how your shoot goes. Why not post a few keepers to the forum…
August 16th, 2007 at 11:44 am
Do you use Depth of Field Preview?…
Depth of field preview is a function included with most DSLRs, but most people tend to not use it… I know its a rarely used feature for me. For those who don’t use it but want to learn how, Sublime Light has written an informative article e…
August 21st, 2007 at 12:16 am
Nice article. Even i never used it before taking this shot http://www.flickr.com/photos/mohan_subramanyan/1036458331/
When the DOF button was not used, the image in the viewfinder didn’t show the metal-grid. I got suspicious and then I used the DOF button and i composed this. The DOF button is very helpful in similar shots.
August 21st, 2007 at 9:15 am
Thanks for the comment Mohan. This is something that I didn’t even think to mention in the article. When you’re looking through the viewfinder, the depth of field is as shallow as your lens will allow. This means that objects that are extremely close (such as that grid, or even closer…dust on your lens) won’t be visible because they’re so blurred. Narrow down the aperture and boom…they come into view.
August 24th, 2007 at 7:23 pm
Hey Tim,
Just wanted to let you know — the Nikon D40 and D40X are examples of modern digital SLR cameras that lack a depth of field preview button. Real shame — I really like the D40 and wanted to buy one until I found that out. I’ll either have to go with a D50 or D80 or go with another brand (I am currently shopping for my first DSLR).
August 24th, 2007 at 9:38 pm
Sam, thanks for that info. I’ve been a Canon guy since I got my first DSLR (a D30) and don’t have much exposure to Nikons. I had no idea those cameras lack that feature. You’re absolutely right, it is a shame. While it’s not really a showstopper to be missing the feature, it is nice to have from time to time.