01-15-2011, 08:05 PM
[quote name='genotypewriter' timestamp='1295119308' post='5545']
6000/(104.3/73.7) ~= 4240 pixels wide
[/quote]
I'll show you the error
[quote name='blende8' timestamp='1295119677' post='5546']
I don't know what you are calculating, Rainer.
Focal length is proportional to HFoV.
If you double the FL you get twice a much on your image.
[/quote]
No ... VoF (regardless of horizontal, diagonal or vertical) is only
approximatly linear ... and only if you stay quite near to the startingvalue ...
For everythig more global, FoV of a rectilinear lens follows the function:
FOV (rectilinear) = 2 * arctan (frame size/(focal length * 2))
with the arctan-function as a nonlinear element in it ... for small differences
of the term within the arctan-function, you can approximate this by a linear function ...
but going from 14 mm to 24mm is nearly a factor of 2 ... that is a very long way from
being a small change.
For a better and in depth explanation .. see here:
http://en.wikipedia.org/wiki/Angle_of_view
6000/(104.3/73.7) ~= 4240 pixels wide
[/quote]
I'll show you the error
[quote name='blende8' timestamp='1295119677' post='5546']
I don't know what you are calculating, Rainer.
Focal length is proportional to HFoV.
If you double the FL you get twice a much on your image.
[/quote]
No ... VoF (regardless of horizontal, diagonal or vertical) is only
approximatly linear ... and only if you stay quite near to the startingvalue ...
For everythig more global, FoV of a rectilinear lens follows the function:
FOV (rectilinear) = 2 * arctan (frame size/(focal length * 2))
with the arctan-function as a nonlinear element in it ... for small differences
of the term within the arctan-function, you can approximate this by a linear function ...
but going from 14 mm to 24mm is nearly a factor of 2 ... that is a very long way from
being a small change.
For a better and in depth explanation .. see here:
http://en.wikipedia.org/wiki/Angle_of_view