Depth of Field Question

[CoolComfort]

I recently downloaded a depth-of-field calculator for my IPad and while I was messing around with it I raised a question for myself that I couldn't answer:

Is the depth-of-field calculation the same for a zoom lens as it is for a fixed focal length lens for the same distance, focal length and appature?

Thanks..........Doug

[Jim Poor]

Yes.

I really hate the 10 character rule!

Originally Posted by CoolComfort

I recently downloaded a depth-of-field calculator for my IPad and while I was messing around with it I raised a question for myself that I couldn't answer:

Is the depth-of-field calculation the same for a zoom lens as it is for a fixed focal length lens for the same distance, focal length and appature?

Thanks..........Doug

[private]

As long as the zoom lens can acheive the same aperture as the fixed focal lens. The kit lens 18-55 will not have the same DoF unless the aperture is for example 5.0. The kit lens will not be able to get to 1.8.

[CheaperKings]

Originally Posted by Jim Poor

Yes.

I really hate the 10 character rule!

D'oh! You stole my answer!

[daft_biker]

Originally Posted by Jim Poor

Yes.

I really hate the 10 character rule!

Maybe to be 10k compliant we could go with; Yes, if the focal length markings on the zoom are accurate?

On zooms the focal length markings at the extremes of the range tend to be pretty accurate but the ones in the middle can be a fair bit off. Then there's the focus distance to consider as that can have a significant effect on the angle of view too.

Not that it's likely to matter