Techie question.

[sponner]

I believe that for a given aperture/focal length the 4/3 camera has a wider dof than an aps-c sensor.

At times I find a wider dof very useful so i like this feature.

I have two questions for anyone with enough technical nouse;

a) at equivalent focal lengths e.g., 150mm on 4/3 and 200 mm on aps-c is the dof the same.

b) Will the dof be greater on a sensor with huge mega-pixels like the D800 be greater if you stand further away then crop in to a similar 12 mp size image taken with a 4/3 camera.

Hope they make sense, any advice appreciated.

[snaarman]

Re: Techie question.

Hmm. This is such a complicated field, I would suggest putting all the numbers into the on line dof calculator

http://www.dofmaster.com/dofjs.html

and comparing the results

Pete

[sponner]

Re: Techie question.

Why didn't i think of that!

No. 1 is answered the Oly has a noticeably wider dof

(focal equivalent 180mm, f4, 20 feet = 1.78ft v 1.33 ft)

Still can't work out the answer to no 2 though

[Wally]

Re: Techie question.

May not be of much use... I have an old rangefinder lens with DOF markers. As this calculates at 35mm in the true sense [if there is such a thing] might it not be possible, using such a lens, to work out a depth of field with might what be just a few simple adjustments with regards the new sensor size?

I'm sure also, I've read somewhere that depth of field can be worked out [seen in real time] when using the live view function. Zoom in and focus on the subject allows you to see what is and out of focus. A tape measure as the subject would give fairly accurate readings... just a thought.

[Ian]

Re: Techie question.

You need to adjust the aperture as well as the focal length so the equivalent dof for the equivalent APS-C field of view compared to Four Thirds 100mm f/2.0 is 150mm f/2.7.

These figures are based on calculations using the circle of confusion figures for each combination of focal length, aperture and frame size, but does not take into account sensor resolution.

If sensor resolution is very low or the viewing distance of a screen or print is far then the apparent depth of field will increase and vice versa, but the differences perceived will be fairly small unless there are massive differences in the resolutions with the lower resolution sensor being extremely low resolution. In other words with normal use and comparing modern cameras, resolution is not a significant factor in depth of field.

Ian

Ian

[theMusicMan]

Re: Techie question.

You need to adjust the aperture as well as the focal length so the equivalent dof for the equivalent APS-C field of view compared to Four Thirds 100mm f/2.0 is 150mm f/2.7.

These figures are based on calculations using the circle of confusion figures for each combination of focal length, aperture and frame size, but does not take into account sensor resolution.

If sensor resolution is very low or the viewing distance of a screen or print is far then the apparent depth of field will increase and vice versa, but the differences perceived will be fairly small unless there are massive differences in the resolutions with the lower resolution sensor being extremely low resolution. In other words with normal use and comparing modern cameras, resolution is not a significant factor in depth of field.

Ian

Ian

WOW - an on a Sunday morning too, Ian You lost me after the second line... haha!!

[Wally]

Re: Techie question.

WOW - an on a Sunday morning too, Ian You lost me after the second line... haha!!

I got as far as the circle of confusion before realising I had been lost from the very beginning... 'You' - Now I know why it's thus called.

[snaarman]

Re: Techie question.

I said it was a complicated field