>If you put a 20mm and a200mm lens on a camera, both at the same aperture
>and vary the camera-to-subject distance so the image is the same size on
>the film, depth of field will not differ.
It's not true at all. Not out of macro regions.
You can say it louder but it will not be true.
Just use the formulas or take the photos. Use the scientific method.
With a 20mm lens at 5m you get a magnification of M=0.0040, at f/8 you get
DOF from 1.4m to infinity.
With a 200mm lens at 50m you get at magnification of M=0.0040 too, af f/8
you get DOF from 40m to 66m (you don't reach infinity).
In order to make a fair comparison, as the focusing distance is different,
just compare the range of magnification which will get DOF, using the 20mm
lens you get DOF from M=0.014 to M=0, using the 200mm lens you get DOF from
M=0.005 to M=0.003. Remember, both are focused at M=0.0040.
>regards,
>Henry Posner
>Director of Sales and Training
>B&H Photo-Video, and Pro-Audio Inc.
>http://www.bhphotovideo.com
Best regards
Vicente
*
****
*******
***********************************************************
* For list instructions, including unsubscribe, see:
* http://www.a1.nl/phomepag/markerink/eos_list.htm
***********************************************************
