Online DoF calulator

Is the CoC when using an on-line DoF calculator based on the coverage of the particular lens or is it based on the particular format being used? If it is format, then what is the CoC of 4x5 that I would use to input into the calculator?

If it is the lens, then how do I find that out for the lens I am using?

I have read that 4x5 CoC is 0.11, but this seemed not to be associated with focal length or coverage.

Any help is appreciated, thanks.

Chuck

CoC is based on your enlargement and your personal standards. At least that's what I've always thought.

Nick Zentena said:

CoC is based on your enlargement and your personal standards. At least that's what I've always thought.

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My thoughts as well. If the enlargement is an 8x10 the CoC would be different for 35mm, 120, 4x5 and 8x10. If each is being enlarged by 2x or 4x then the CoC would become similar. Diffusion (or is it diffraction?) caused by the enlarger head being further away from the print on the larger formats might begin to negate this. I tend not to worry as much about the CoC on 35mm and 120 and simply try to get everything I need in focus without going above f11 or 16. On 4x5 I have yet to enlarge anything to the point were a too small aperture has caused problems, but I tend to get what I'm after by staying at or under f22. I use mostly shorter lenses.

I use a windows application called fCalc which allows you to change the Coc if you desire.

I also like fCalc. It gives you a standard CoC value for each format, and then you can adjust as you prefer. Rather than changing the CoC value, I'm more likely just to stop down one extra stop from the recommended f:stop.

Do a search on Paul Vanralwee (or go to www.vanralwee.com) and take a look at the explanation provided in the manual that is with his downloadable dof calculator. There are quite a few examples and explanations in there that should be of help

I've just taken a look at fCalc too, and there is a brief and clear explanation of coc in the online manual.

A.C. said:

Do a search on Paul Vanralwee (or go to www.vanralwee.com) ...

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Try www.vanwalree.com (but be careful about his explanation of the effect of pupil magnification on depth of field - it's wrong, I believe).

Best,
Helen