DOF Preview Button

[johnc24]

Hi all

Can anyone explain to me the DOF preview button.
I understand its to kinda spot things that may bbe intruding in a shot.But I dont really get it?

All that happens to me is the screen goes brighter or darker.
Can anyone point out its benefits or how it works.

Thanks all

Regards
John

[dkippen]

In my XTI book it says:

Press DOF preview button to stop down to current aperature setting. You can check the DOF (range of acceptable focus) through viewfinder.

When you want to see effect of current DOF, select lowest aperature while holding DOF preview button, look at viewfinder. Then turn dial to right to set higher aperature to see how DOF changes.

I personally have not used it, as I'm not that coordinated. Hope this helps.

[johnc24]

Hi debbie

Thanks

But I have the button pressed while changing aperture and I can see feck all difference.Its weird.But im sure ill get it one day!

regards
John

[dkippen]

John -

You peaked my curiosity. I tried this and what's basically happening is the lens opening (f-stop) is getting smaller, creating a greater depth of field. Meaning, your foreground will be in focus and the background will start to blur. If you look at your F-stop as you dial, it will change as you turn the dial.

On my camera however, I had to hold the DOF preview button, turn the dial and hold the AE lock button to see the changes.

[johnc24]

Yeah I was just messing with it myself.I only really notice it when I take two Photos.

Its very hard to see using the DOF preview button.Although that said maybe its easier to see the difference in pure daylight.
Im only playing with it in my living room.

I can notice the changed but its stressful on the eye.

Erm...the AE lock thats the left hand button under the main power button aint it?

It didnt make any difference with me holding that.

John

[dkippen]

John -

I made sure I had plenty of light for this practice and yes - very hard on the eye!! On my camera, the AE lock is upper right of the preview screen. What camera do you have? I have an XTI.

[johnc24]

Hi debs

This button here i Think it is.Am I wrong?

http://www.flickr.com/photos/21384213@N02/2214976239/

Yes its an XTi also.

John

[johnc24]

Of course I have the European XTi. The 400D equivalent.maybe its laid out slightly different.

Its the button with the * above it isnt it?

john

[dkippen]

Now that I'm thoroughly confused:confused::confused:

Yes, the button you're referring to is the AE lock. For some reason, I thought the AV button (on the top right of the preview screen) was the AE lock as when I pushed that button and turned the dial, my f-stop would change. Boy - do I feel sheepish.

No more playing with the camera tonite for me!!!:(:(:(

BYW - looks like this might take me awile to "get it" as well.

[johnc24]

haha

Yeah I think ill leave it myself as well.

Ill have to get someone to teach me hands on how it works.

Thanks for all your efforts though debbie, appreciate it

regards
John

[dkippen]

Not a problem. For me, it's one of those things that I never used, didn't understand, so I left it alone. I'll go back to my own little corner now and process more pictures.

[Snappers]

I have tried to use it before, but it never seemed to do anything for me.

[ladyups]

Sometimes, I can see the DOF on my camera but it all depends on what I'm shooting at. If any of you figure it out, it would be nice if you shared your findings.

Mary

[jonrayner]

John -

You peaked my curiosity. I tried this and what's basically happening is the lens opening (f-stop) is getting smaller, creating a greater depth of field. Meaning, your foreground will be in focus and the background will start to blur. If you look at your F-stop as you dial, it will change as you turn the dial.

On my camera however, I had to hold the DOF preview button, turn the dial and hold the AE lock button to see the changes.

When pressing the button, the outside of the shot goes dark, is it the dark areas that blur, I am assuming it is.....

[sjgarth]

Maybe I can help.

When you are looking through the viewfinder normally, the camera holds the aperture at its maximum (smallest f number) so that you can see what you are looking at. It lets through themaximum amount of light. However, what you are looking at does not show the depth of field that the final picture will have.

When you press the shutter release, the aperture is moved to the aperture setting before the picture is taken. This means that the picture has the depth of field set by the aperture setting.

When you press the depth of field preview button, the aperture is moved to the aperture setting so that what you are looking at through the view finder shows the depth of field that the picture will have. Unfortunately it also reduces the light coming through the viewfinder. so the view is somewhat darker.

Personally, because I use digital, i do not use the DOF preview, I look at the LCD image after taking the picture.

Hope this helps

[Snappers]

So if I understand you correctly Steve, You would need to press the shutter button at the same time as the DOF button to see the effect through your viewfinder. Like you say though, it is as easy to take the picture and then look at it on the LCD screen.

[sjgarth]

No, not quite right, the DOF button moves the aperture to the same setting as when you take the picture, so that when you look through the viewfinder you are looking at the same DOF as the final picture. When you let go of the DOF button, the aperture goes back to maximum so that you are now looking at maximum light, but the wrong DOF.
You do not have to press the shutter to preview the DOF, pressing the shutter will, of course, take the picture.
Two seperate functions move the aperture to its true setting from its maximum- pressing the DOF preview button to look at the DOF before taking the picture, and pressing the shutter button to take the picture.
Obviously, this function is only available for SLR cameras.

[Snappers]

Right OK. I'll have a play with it next time I have my camera out.

[ladyups]

Thank you, Steve, for this information...makes it much clearer as to what it is suppose to do.

[jerryph]

I have a Nikon, not a Canon, but the way it works on my camera is that it dims the background more when I use numerically smaller (a more open) aperture. With a little messing around, you will be able to "see" what is and is not in focus using the DOF button.

Of course, we can take that one step further and know that with some practice and a little experience, we will be able to preset the aperture to where we want it and know in advance how it will look. :)

[Snappers]

It would be a nice feature but sounds a little to hit and miss, whereas, if you take the pic and look at it on your LCD screen, you can then see the effect. If you don't like it delete it and carry on.