On Dec 1, 2005, at 9:38 AM, John Francis wrote:
On Thu, Dec 01, 2005 at 04:15:49PM +0000, Kostas Kavoussanakis wrote:
On Tue, 29 Nov 2005, Godfrey DiGiorgi wrote:
Be aware that the difference in field of view between 90 and
105mm is
quite small. See
http://homepage.mac.com/godders/2zmFoVcomp.jpg
for comparison. The real advantages of the 24-90 are much more
field of
view at the wide and and better performance when wide open at the
tele end.
Thanks, Godfrey. Can you help me understand your diagram? Is the
small, green rectangle the FOV at (more or less) 90?
The large green rectangle is the approximate field of view at 24mm vs
the larger white rectangle at 28mm. The small green rectangle is the
approximate field of view at 90mm vs the smaller white rectangle at
105mm.
Here is an
exercise I would like to solve: "Assuming a lens at 90mm and another
at 105mm, how much closer to the subject should one go so as to get a
photograph with the same dimensions on the recording medium".
Well, that's easy. You should move forward until you're 90/105 of
the distance you started from.
As John said... ;-)
Two on-line calculators that are useful for FoV ...
Gives you field of view at distances: http://www.dudak.baka.com/
fovcalc.html
Gives you angular field of view: http://www.mat.uc.pt/~rps/photos/
angles.html
Godfrey
