Focus Question.

[Roy G. Biv]

When shooting above f10, does focus really matter? Isn't everything pretty much in focus? Forgive me if its a stupid question.

 

[nickb]

Are you talking about macro shots or ultra wide angle landscapes? For macros, the answer is 'no'. A D90 type camera, with 100mm macro lens shooting at 3' at f10, has a depth of field of just 0.1' (1.2"). In contrast, with a 12mm lens, you can get from 1.5' to infinity in focus at the same time.

 

[Roy G. Biv]

Is there a chart available that you know of? I was speaking of non macro shots.

 

[IPT]

There are charts but it's been so long that I've delt with one. Focal point does matter, even at a small F stop (like F22). There is something called the "hyperfocal distance". Forgive me here, because it's been a long time and I may be a little off (rusty) so please confirm what I say.

The optimal place to focus to get the maximum DOF is approximately 1/3rd into the scene. The wider the Fstop (like F2.8) the less distance your plane of focus will extend from either side of that point. The smaller it is the, the larger area will be in focus.

A quick Google search found me this. You may want to give it a read or do more searching for your lens/hyperfocal point.

http://www.vividlight.com/articles/3513.htm

 

[nickb]

I got my numbers from this on-line calculator:

http://www.dofmaster.com/dofjs.html

 

[Roy G. Biv]

Great links. Thanks.