Archived posting to the Leica Users Group, 2004/07/08

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]

Subject: [Leica] Ted, Tina, Henning and Bob on "focus and recompose"
From: henningw at (Henning Wulff)
Date: Thu Jul 8 10:21:16 2004
References: <> <003001c464e1$f967b8c0$4649c33e@sigmafli1cclvg>

At 1:51 PM +0200 7/8/04, animal wrote:
>  > Ted Grant wrote the following regarding this "focus and recompose"
>  > thread:
>  >


>  > Ted, I can't begin to express my gratitude to you not only for your
>>  grace with the tools and the medium, but with your generosity in sharing
>>  the benefits of your years of experience.  In fact, your last lengthy
>>  dispatch regarding your shooting technique reminded me that while my
>>  reflexes for capturing what I'm after keep improving, it's the quantum
>>  leap into being able to anticipate the best instant to push the button
>>  that is still out of reach.
>>  Tina, you also get the "life and its representatives wait for no nerd"
>>  concept.
>>  Henning, I'm glad someone besides me recognises the reality of field
>>  curvature for our work.
>>  However, I'm here to tell you that anyone who thinks that they can just
>>  focus with the rangefinder and then put the main subject anywhere else
>>  in the frame with a 35mm f2 lens wide open is missing an important
>>  refinement in Leica M technique.
>>  I have frames on my contact sheets that I know were focussed accurately
>>  according to the rangefinder with a fast enough shutter speed where the
>>  reframed faces are just plain out of focus.
>>  Now; whether or not we can become facile enough to pull off an
>>  appropriate compensation maneuver without losing the thing that makes us
>>  want to shoot this frame in the first place is the real question.  But
>>  anyone who claims that the effect just doesn't exist is wrong.
>>  Ted, the "never had it happen that I'm aware of" part of your response
>>  may be all too true.  And Tina, this ain't about charts on walls - it's
>>  about people's eyes being in focus.
>>  One of the potential benefits of this list is the possibility that
>>  intuitive artists and those who sometimes resort to basic arithmetic and
>>  trigonometric principals will learn something from each other.
>>  Bob Palmieri
>>  _______________________________________________
>Also the people who do not should realise that without those who do they
>would travel on foot and practise PJ with a sketchbook.
>best regards
>simon jessurun

This 'trigonometric focussing error' is without a doubt a real issue, 
and obviously becomes a greater problem with very fast wideangle 
lenses, but we have a dilemma here: rangefinder focussing occurs in 
the center of the image, and typical rangefinder use tends to be 
fluid, intuitive and rapid. Doing compensation after focussing ruins 
a lot of that, and while you now may have the focus point better 
defined, your image content is often changed. You often have the 
choice of technical superiority or content superiority. I know where 
I stand on that. Possibly if you regularly find that such 
compensation is necessary and worthwhile you are using the wrong type 
of camera.

On the matter of field curvature, I have many lenses that have fairly 
flat fields, but the faster ones tend to have greater curvature. It 
is the latter that cause more focus problems, and they, to a certain 
extent, are 'self-correcting'. Not perfectly of course, but helpful 
in the right direction. The Noctilux is one of them. Also, when using 
a lens like the Noctilux the subject tends to be fairly close to the 
center, so the trigonometric error is slight.

If I want a very sharp image across a field, and am worried about off 
center subject sharpness, I use a camera with a ground glass, and 
stop the lens down to check focus after focussing wide open. This 
works very well in architecture, and I've never had a building go off 
for lunch while fiddling around with this.

For most photographers, it's important to know what the issues are, 
and then know when to pay attention to special ones or ignore them.

    *            Henning J. Wulff
   /|\      Wulff Photography & Design
  |[ ]|

Replies: Reply from bdcolen at (B. D. Colen) ([Leica] Speaking of weddings....)
In reply to: Message from rpalmier at (Robert Palmieri) ([Leica] Ted, Tina, Henning and Bob on "focus and recompose")
Message from s.jessurun95 at (animal) ([Leica] Ted, Tina, Henning and Bob on "focus and recompose")