[Leica] new Puts article

[leicaluvr at comcast.net (Tom Schofield)]

So, Henning, according to you I will get the same dof shooting the same
subject at the same distance and aperture with a 50mm on 35mm film as with
an 80mm on 6x6?  

All of the confusion that creeps up when people talk about dof varying with
distance, focal length or format loses sight of the basic rule:  At the same
aperture and subject distance, dof remains the same as long as the
magnification ratio remains the same, i.e. dof remains the same so long as
image size at the focal plane remains the same.  

Since image size at the film plane is smaller with smaller formats, i.e.
magnification ratio is smaller, dof is deeper.  (That's why a fixed focus
Minox 15mm 5.6 goes from 1m to infinity).  With larger formats, image size
at the focal plane is larger, i.e. magnification ratio is greater, so dof is
shallower.  (Again, assuming the same aperture and distance.)

Erwin is saying a smaller sensor is like a smaller format -- lower
magnification ratio, hence deeper dof at the same aperture and distance.  I
agree with him.

Tom Schofield

-----Original Message-----
From: lug-bounces+leicaluvr=comcast.net@leica-users.org
[mailto:lug-bounces+leicaluvr=comcast.net@leica-users.org] On Behalf Of
Henning Wulff
Sent: Monday, June 27, 2005 10:45 AM
To: Leica Users Group
Subject: Re: [Leica] new Puts article

At 3:34 AM +0200 6/25/05, animal wrote:
>http://www.imx.nl/photosite/comments/c014.html

An awful lot of sloppy/illogical thinking. Hardly any of his 
conclusions or statements bear careful analysis.

The thing I agree with, though, is that the M lenses and mount are 
unsuitable for full frame digital use as I have contended for years, 
for all the reasons expressed previously. Erwin seems to try to work 
backwards from this position, and force various other concepts which 
are not necessarily relevant to support the result.

Hard to tell what the point of the article is.

-- 
    *            Henning J. Wulff
   /|\      Wulff Photography & Design
  /###\   mailto:henningw@archiphoto.com
  |[ ]|     http://www.archiphoto.com

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