DSLRUsers.com

when i press the DOP preview button on the 400d should it show me the actual picture that the camera will take or something else? am i reading my instruction book correctly? i can see the picture getting darker and lighter as i adjust the aperture. please help!

It should show you the DOF you'll be getting.

so is hould be able to se what is in and out of focus? if this is true then what am i doing wrong?

What it does is to actually close the aperture of the lens to what it will be when you take the photo. In doing so, two things happen:

1) depending on the aperture you have set, the image will get darker because the 'hole' that light is coming in is smaller.

2) because of '1)' you will see ( IF it is not too dark!) what the DOF really is.

huw62 wrote:so is hould be able to se what is in and out of focus? if this is true then what am i doing wrong?

Yes that is right.

When you press the button, it stops the lens down and your viewfinder will become dark depending on your aperture setting.

What you see in the viewfinder is the actual depth of field, you will notice things go sharper.
You can try it with the monitor in front of you, make it go on screensaver mode with the WinXP logo, dial in an aperture of say f/8 or f/11, focus away (manual focus) from the monitor and press the DOF preview, you will eventually start seeing the logo itself.

thanks for the prompt answers, i will have another play tomorrow. bed time for me as i am up at 4.30 for work every morning. cheers.

just to maybe help clear this up a little more. when you look through the viewfinder normally, the lens is always set to wide open, no matter what you have the apeture set to. the apeture only closes up when you take the actual shot or push the d.o.f. button.

Do nikons have such a button and is it of much use in practice?
I assume with dslr the image is displyaed immediately and the shot can be retaken if you are unhappy with the DOF.

rah wrote:Do nikons have such a button and is it of much use in practice?
I assume with dslr the image is displyaed immediately and the shot can be retaken if you are unhappy with the DOF.

Mostly, no, and yes, you're absolutely correct.

rah wrote:Do nikons have such a button and is it of much use in practice?
I assume with dslr the image is displyaed immediately and the shot can be retaken if you are unhappy with the DOF.

Yes, no.
Assumption correct.

Most nikons have it I think a few models may miss out, I'm in a practical sense I rarely use it. It is good for making sound like you took a photo when you didn't.. which is sometimes useful... or just good for playing tricks...

Good way to get people to look at the camera, if your close by. Make the click with DOF button, and then snap the shot when they look up.

I never new it would make a shutter noise. That would be annoying if you had composed people and they thought the shot had been taken and turned away!

its a useless button, as already said take a shot then go again if its not wat u wanted. the viewfinders too small really to get a great idea anyway
in fact i totally forgot my 400D had this until i saw the topic title lol

Some older manual cameras Pentax Spotmatic for example had this function but called it something else, on these cameras the arpeture was always wide open e.g. f1.4 (in auto setting) to make it easier to focus, and closed down to the selected arpeture when the shot was taken or the switch used. I use it on both my Spotmatic and D70, not ot check D O F but to see the overall exposure I find the image through the view finder in general to small to really see DOF, maybe just my eye sight.

On my Nikon lens the arpeture is locked at the smallest arpeture ( for auto focusing, metering) as oposed to largest on the Pentax lens so I guess on these lens it works in reverse for the same effect.

Cheers Rick.