Re: (no subject)
- From: "David Young" <telyt@xxxxxxxxx>
- To: leica@xxxxxxxxxxxxx
- Date: Tue, 05 Jul 2005 13:43:44 -0700
Jim,
I sorta knew all that... my complaint, I guess, was that at 800mm there is
still precious little DOF!
Thanks for the URL. It seems will done and I will study it. :-)
Cheers!
David.
-----------
On 05/07/2005 at 12:32 PM Jim Brick wrote:
>David,
>
>Depth Of Field is a function of f/stop and image size. An 80mm lens on a
>4X5 has precisely the same DOF as an 80mm lens on a Hasselblad, which has
>exactly the same DOF as an 80mm lens on a Leica, or a 1.6x digital sensor,
>in every situation. One does not give less or more DOF than the other.
>
>Image size is a direct function of the focal length, nothing else. Your
>DOF
>is based entirely on the 800mm optic (400x2,) not the 1280mm equivalent
>optic. If you stuck a piece of Minox film over the sensor, you might get a
>2000mm equivalent optic, but the actual optic is still 800mm. So
>everything
>is based on 800mm, regardless of the film/sensor size.
>
>Here is a DOF calculator:
>
>http://www.outsight.com/hyperfocal.html#dof
>
>Which explains the digital LMF (Lens Multiplier Factor) which you are then
>told to use the lens actual focal length in the calculations, not the
>equivalent focal length.
>
>Jim
David Young,
Logan Lake, BC
CANADA.
Personal Web-site at: http://www3.telus.net/~telyt
Leica Reflex Forum web-page: http://www3.telus.net/~telyt/lrflex.htm
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