[pure-silver] Re: Depth of Field (35mm vs. 4x5 or 8x10)

  • From: "Gene Johnson" <genej2@xxxxxxx>
  • To: <pure-silver@xxxxxxxxxxxxx>
  • Date: Fri, 29 Oct 2004 20:53:47 -0700

I think the focal length proportionality goes more according to the diagonal
dimension of the film than the area.  Area is kind of a second degree
function because it's film format length X width.  a 45mm normal for 35mm
film pretty much corresponds to about an 80mm for 2 1/4 and about 160mm  for
4x5.

Otherwise we'd have 180mm normal lenses for 2 1/4 and 800mm normal lenses
for 4x5.

Have I completely confused you yet?  That is my specialty:)


----- Original Message -----
From: "Jim Brick" <jim@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, October 29, 2004 5:48 PM
Subject: [pure-silver] Re: Depth of Field (35mm vs. 4x5 or 8x10)


> At 04:36 PM 10/29/2004, Gene Johnson wrote:
>
>
> >1600mm?  You sure about that Jim?  I was thinking more like 400.  He used
a
> >100mm on his 35mm camera
>
>
> The 4x5 frame is roughly 16x the 35mm frame. This is all about image
> magnification. 16x 100 = 1600.
>
> But I could be wrong and would gladly accept another proof.
>
> Jim
>
>
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