Re: [Leica] 28 mm M Lens recommendation

[Henning Wulff <henningw@archiphoto.com>]

At 8:11 PM -0700 6/7/01, Ray Moth wrote:
>  > Frank,
>>
>>  The depth of field is different with each lens even if they are the
>same
>>  distance from the subject therefore the perspective is different.  Or
>
>am I
>>  wrong?
>
>Johnny Deadman wrote:
>
>the DOF is the same, I think, *when you take into account the
>magnification*.
>======================================================================
>AFAIK, the DOF will not be the same if the shots are enlarged to the
>same size. For example: two shots are taken of the same scene, with
>28mm and 35mm lenses, from the same position, with each lens set to the
>same aperture and the focus of each lens set to the hyperfocal length
>for that aperture. The shots are then both enlarged to 8x10. The DOF of
>the shot with the 28mm will appear greater than with the 35mm.
>However, the magnification of the two enlargements would not be the
>same, i.e. a particular feature of the scene would be smaller in the
>28mm shot than in the 35mm shot.
>
>However, if you were to make a bigger enlargement from the 28mm shot,
>so that the area in the new enlargement covered by a particular feature
>of the scene was the same as that covered by the same feature in the
>8x10 from the 35mm, the magnification of the two would then be the
>same. The DOF in that new enlargement would appear the same as in the
>8x10 print from the 35mm.

The critical thing is the "ON FILM MAGNIFICATION". If the object 
(plane) you are photographing is the same size on the film, and the 
aperture is the same, then the DOF is the same. 24mm; 200mm - it 
doesn't matter.

That said, you hardly ever do something like that in the real 
shoot-em world. When you take a photo with a wideangle, you usually 
have stuff a lot smaller on film, and therefore you get more DOF. 
Just as you usually use a 28mm lens from a certain point of view to 
get more in than with the 35. Therefore you wind up with a smaller 
main subject, a greater angle of view and more DOF.

On a personal note, while I appreciate the differences between a 50, 
75 and 90, I don't have anything between 35 and 21 for the M. I just 
don't see things that way. However, I use 24 and 28mm shift lenses on 
SLR's all the time. In fact, those are the main focal lengths I use 
on SLR's. Ce la focal length.

- -- 
    *            Henning J. Wulff
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