aperture and viewfinder

Tighearnach · Feb 5, 2009

hi

So I'm taking a picture with a 50mm f/1.8 and it's set to f/22. I look through the viewfinder and compose and then half press shutter. The lens focuses. Am I looking at the image at f/22 or at the lens maximum aperture?

Sorry just a bit confused
Thanks
T

Samanax · Feb 5, 2009

Tighearnach said:
So I'm taking a picture with a 50mm f/1.8 and it's set to f/22. I look through the viewfinder and compose and then half press shutter. The lens focuses. Am I looking at the image at f/22 or at the lens maximum aperture?

At maximum aperture. To view the image at f/22 you have to use the depth of field preview button (see the camera manual for location)...the viewfinder image will darken quite a bit at f/22.

Big Mike · Feb 5, 2009

You are still looking though the lens at maximum aperture (F1.8 )
The aperture does not stop down until you press the shutter release button.

Now, some cameras have a DOF preview button. This button stops down the aperture to the set value so that you can see the increased DOF. However, because the aperture gets smaller, it lets in less light and it's harder to see the image. At F22...the viewfinder image would be very dark.

This is how most modern SLR cameras work anyway...if you have something different, this might not be the case.

Tighearnach · Feb 5, 2009

ok. Can't believe I'm only copping this now. So this means that when not shooting at max ap a certain amount of guesswork is involved as to how final image will look? This obviously is reduced with experimce
Thanks

Big Mike · Feb 5, 2009

So this means that when not shooting at max ap a certain amount of guesswork is involved as to how final image will look? This obviously is reduced with experimce

When it comes to DOF....yes. However, DOF can be calculated if you want to be precise about it.

Realistically, the viewfinders on most DSLR cameras are quite tiny and it's rather hard to really see your DOF with the preview. You do get a good feel for it with experience and you can always bracket a few shots to be safe.