Depth of Field

[wingflapp]

Is it correct to say:

The depth of field resulting from using a 200mm Focal Length at f/4 would be the same as using a 100mm Focal Length at f/2. (As long as the subject took up the same amount of the frame)

Yay? Nay?

wing.

[RichardTaylor]

No.

Plug the numbers in.

Online Depth of Field Calculator

[wingflapp]

Thanks much. More reading to add to my list.

[ravncat]

One interesting relationship that you might find -

Is that your depth of field is approximately the same between a 100mm at f4 at 5 feet and a at 200mm f4 at 10 feet or a 50mm at f4 at 2.5 feet....

It doesn't always hold together, especially as your distance get's really close or far - and you don't go super telephoto or super wide angle... (The more extreme you get, the more this diverges from being the same, but for back of the envelope / in general, you'll find roughly the same depth of field at a given aperture with twice the focal length and half the distance, or vice versa.