(Basic) DOF question

[aam1234]

Situation 1: You stand at a certain distance with a camera that has 50mm and take a picture.
Situation 2: You stand at double the distance above but with a camera that has 100mm and take a picture.

Would there be a difference in the pictures between these two situations. I know in this scenario the 100mm will give slightly more compressed perspective. But other than that, are there any differences, especially in terms of DOF.

What do you think.

[Rense]

aam1234,
Using dofmaster you get:

50mm/ f4.0/ 10 meters: dof = 12.4 m
100mm/ f4.0/ 20 meters: dof = 10.1 m

[aam1234]

Thanks Rense,

Hmm, that's not what I expected, thought it will be the reverse. Interesting.

(why didn't I think of DOF calculator, duha).

[Mark McCall]

There's other factors that affect DOF:

Aperture selection
Focal Length (already mentioned)
Distance from the front element of the lens to the subject.

The shorter the distance between the lens and subject, the shallower the depth of field.

Use all three to your advantage.

[jgoeden]

I read this somewhere but if you frame the subject the exact same framing in the picture, no matter the focal length the DOF will be the same (if the same aperture is used). I know this isn't exactly what your question is asking but hope it helps a little.

[JohnC]

Pretty good description and examples of situations are available at http://www.pinnipedia.org/optics/dof.html

John

[Max@Home]

...and if you like it 'technically explained' there are some good articles on DoFMaster too:

From your question I gathered you were investigating 'Depth of Field When Image Size is Constant' )

...*my* €0.02...

Kindest regards!

Max@Home