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DOP preview button
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Hi everyone,
I hope you can help me,I’m really starting to get to grips with my Canon 400D and am loving it but there’s one little button that I’m just not sure what it does. It’s the Depth Of Field preview button.
I know in theory that it should, well, give me a preview of the DOF, but when I press it it just makes what I see a bit darker.
I’m not really sure what I should be seeing/looking for when I press it.
All help would be really appreciated thanks!
Making it darker does make it more difficult to see-
but you should be able to see an increase in depth of field,
if you look hard-There are limitations with smaller sensors too-
my 50mm f/1.2 doesn’t even get darker, or show any depth of field increase until about f/2.8,
which makes it difficult to focus manually-
which is a bit of a problem on a manual focus lens-There should be a difference-
make sure you’re looking at something brightly lit, to begin with,
to see the effect-j
What it does is give you a preview of the DOF…sounds like a silly answer but that’s basically it. If you have a subject close to you and something in the background it’ll show you how well in focus the two will be. Obviously the smaller the aperture the darker it will get but you will still make out what is in focus. It takes a little getting used to but certainly worth the effort.
If, for example you want to get a tree in the foreground in focus and the house 60ft away it can be used, Focus, then press it to see if all is as you want it. You can close down the aperture (f16 to f22 and upwards) to get both in focus or open up if you want a shallow DOF (f8 – f5.6 and downwards). Practice!Alan.
[EDIT] or what JB just said! :D
Thanks guys
:)I’ve been doing fine just setting my aperture manually to what I want (or what I feel I want) and then taking the picture and reviewing it on the screen, and I guess I’ve been lucky so far that it’s always worked out ok with a little trial and error, but I really want to know my camera inside out so I’ll start using this more too and reeeally looking hard at it to see what is shows me.
I just didn’t know if I was missing something obvious.
I guess I just wasn’t looking hard enough maybe.I always thought that the dark effect was to show what was not completely in focus, i.e. if it was dark, it was outside the DoF.
Must experiment with some settings to see …
Yeah I kind of thought that myself but then I noticed that often the whole image appeared to get uniformly darker so I was confused (and still am quite a bit!).
When you look through your viewfinder you are viewing the scene at your lens’s maximum aperture. If you have selected a different aperture, when you press the shutter button the camera closes the aperture iris to the selected aperture just before the shutter opens, then opens it back up again after the shutter closes.
The DOF (depth-of-field) preview button simply closes the iris to the chosen aperture on command, so you can view the scene through it. As you know, aperture controls depth-of-field, so the smaller the aperture the greater the depth-of-field.
The viewfinder gets dark because there is less light coming through the lens (due to the smaller aperture). You will notice that the viewfinder gets progressively darker as you stop your aperture down (the f-numbers get higher). If this is unclear, look through the front of your lens while you press the button – you will see the physical aperture close down.
If you pay attention when looking through the viewfinder, you will notice things that were out of focus before you pressed the DOF preview button will appear more and more in focus with smaller and smaller apertures. The problem is that the view also gets darker and darker, making it harder to see the subtle changes in focus.
With digital cameras, the DOF preview button is largely obsolete. The best way to check for depth-of-field is to guess at the aperture, take an exposure and zoom in on the LCD to check for sharpness.
Cheers,
Peter
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