Someone explain DOF to me please
- Thread starter Phate
- Start date
http://en.wikipedia.org/wiki/Depth_of_fieldPhate said:Hello all,
as you all know I'm and amateur photographer - keen like all of us here
But DOF is something I have never quite grasped, can someone please explain best they can with possible examples?
Thanks
Soldato
- Joined
- 25 Jun 2006
- Posts
- 4,375
DoF is the distance before and after the subject you have focused on mate. It goes from front to back (i used to think it was side to side for some reason). Your aperture setting affects the DoF, a smaller f/ giving you a shorter DoF and a larger giving you a longer DoF.
i think thats right mate, someone feel free to correct me
i think thats right mate, someone feel free to correct me
Soldato
- Joined
- 5 Nov 2004
- Posts
- 9,302
depth of field is the sharp focus range at specific apertures.
For example. If along a ruler you placed several coins.
1cm - 2p
5cm - 5p
20cm - 50p
60cm - 1 pound
Assuming this ruler is facing down your lens and not across by using a shallow depth of field (ie, F1.8) focus locked on the 2p coin. All descending coins would be blurred in a "bokeh" effect.
Lets now say you adjust focus still at F1.8 to the 50p coin. All coins behind and infront(1pound, 5p and 2p) would again be blurred.
now say you pick your focus at the 50p again but the aperture has now been changed an awful lot to F22. This is full depth of field and means that all your coins front and behind of the one you have focused on are now all in focus. This is because you have set your aperture (F.) down to F22 which means the opening of the aperture is tiny!
Your aperture is always open to its widest at all times (expect during exposure) this is why you can always preview the shallowest depth of field through your viewfinder at all times. Lets say you dial down your aperture to say F11 and want to preview what that looks like in the viewfinder then you will find a small button next to your camera lens mount (lower left side) push that while your F number is set to anything from its maximum (EG:F11) and your camera will close the lens aperture down to that mark as you hold your finger on that button. This is a great way to see if you have enough depth of field. However that function will be short lived and you will soon enough just know what aperture to use.
For example. If along a ruler you placed several coins.
1cm - 2p
5cm - 5p
20cm - 50p
60cm - 1 pound
Assuming this ruler is facing down your lens and not across by using a shallow depth of field (ie, F1.8) focus locked on the 2p coin. All descending coins would be blurred in a "bokeh" effect.
Lets now say you adjust focus still at F1.8 to the 50p coin. All coins behind and infront(1pound, 5p and 2p) would again be blurred.
now say you pick your focus at the 50p again but the aperture has now been changed an awful lot to F22. This is full depth of field and means that all your coins front and behind of the one you have focused on are now all in focus. This is because you have set your aperture (F.) down to F22 which means the opening of the aperture is tiny!
Your aperture is always open to its widest at all times (expect during exposure) this is why you can always preview the shallowest depth of field through your viewfinder at all times. Lets say you dial down your aperture to say F11 and want to preview what that looks like in the viewfinder then you will find a small button next to your camera lens mount (lower left side) push that while your F number is set to anything from its maximum (EG:F11) and your camera will close the lens aperture down to that mark as you hold your finger on that button. This is a great way to see if you have enough depth of field. However that function will be short lived and you will soon enough just know what aperture to use.
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