Noobish question: how to use DOF preview button?

[cks2k2]

I was reading John Shaw's landscape photography book and he mentioned he uses the DOF preview button everytime. Basically for every shot he uses the DOF preview button to figure out the largest aperture opening he can use to get max DOF for a scene, instead of shooting at a fixed large aperture value i.e. f/22 everytime.

This DOF preview button is one of those features I've never really used or know how to use. I understand it stops the lens down to the specified aperture and the VF becomes dimmer due to the smaller aperture opening, but other than that I have no idea.

Any CSer can explain the correct way to use it?

 

[candycaine]

You can check this out: http://www.kenrockwell.com/tech/dof-button.htm

Hope it helps

 

[giantcanopy]

This DOF preview button is one of those features I've never really used or know how to use. I understand it stops the lens down to the specified aperture and the VF becomes dimmer due to the smaller aperture opening, but other than that I have no idea.

Any CSer can explain the correct way to use it?

Usually the aperture of a lens is kept at its widest even when you set the aperture to a smaller opening, and only stops down to the smaller aperture you specified when you click the shutter button. This helps to maintain a bright and clear view for the user. e.g The 50mm f1.4 lens will still open at f1.4 even though you set to f16, and only stops down to f16 for the shot when u take the shot.

When you press on the dof preview button, the aperture stops down to your adjusted aperture e.g f16 for instance, and you can peep and see how much dof you covered. Of course the flip side being a much dimmer viewfinder

* alternatively with the liveview, within limits i believe you can have an easier view of the dof with the aperture you set with appropriate exposure ( that you adjusted ). It has since replaced my need to press the dof button especially useful for low light situations.

ryan

 

[retrovox]

I was reading John Shaw's landscape photography book and he mentioned he uses the DOF preview button everytime. Basically for every shot he uses the DOF preview button to figure out the largest aperture opening he can use to get max DOF for a scene, instead of shooting at a fixed large aperture value i.e. f/22 everytime.

This DOF preview button is one of those features I've never really used or know how to use. I understand it stops the lens down to the specified aperture and the VF becomes dimmer due to the smaller aperture opening, but other than that I have no idea.

Any CSer can explain the correct way to use it?

I almost never use the DOF preview button. If you shoot long enough, you should be able to gauge what aperture at what distance would yield the amount of focus that you are trying to achieve.