DOF calculators and M8

[wstotler]

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I'm with you, Will. We're on the same page.

 

I do disagree with your statement #2, "DoF exists." Technically, it doesn't exist (in the physical world, definable by formula), but is perceptual (arises in the eye and brain; the formula is approximative).

 

<snip>

 

My point is simply that DoF is fuzzy and no one should take seriously a depth-of-field calculation without understanding its assumptions.

 

Thanks, Howard. I agree with you about the DoF being fuzzy--and I think that's an important point that gets missed. While DoF behavior is measurable, predictable, and is a constant, it's not *solid* like poor diagrams show it to be.

 

I'm not intending to needle you, but DoF does exist, even if it "only" exists as a measurable perception. It exists like the plane of focus exists--even though that plane is only a mathematic concept with no actual measurable width.

 

Cheers,

Will

 

P.S. I'm thinking about the cat's popularity.

[Guest mc_k]

the formula was never intended as anything but a guide, like Sunny 16 or other exposure formula. They are not physical laws. Obviously you can practice photography without ever calculating exposures or depth of field, but a formula can be useful every once in a while. Especially when talking about photography...it is nice to be able to use some numbers instead of just making vague declarations. When someone says such-and-such has a depth of 2cm, it's usually clear where that 2cm came from, and clear that if you actually tried to judge it yourself, you might get 1cm or 4cm or whatever.

 

For sure depth of field is something tangible to talk about.

[Guest mc_k]

...

In other words, the usefulness of the idea of DoF had been waning as we made ever bigger prints from film and is doing so now even more quickly with the advent of digital technologies

...

 

Two pts. at different distances are focused at different distances (behind a lens), and until everyone goes pinhole, the issues involved are the same as they've always been, I think.

 

I think you are lumping the notion of depth of field with that of hyperfocal distance. Selective focus has always been part of the language of photography, and I don't think that's changed any.