Re: [Leica] Depth of Field

[Mark Rabiner <mrabiner@concentric.net>]

Gib Robinson wrote:
> 
> As I recall, there is an ideal point to focus on in order to get the most
> area in focus both in front and behind a subject. Can someone please tell me
> what the rule of thumb is: -- something like "put the subject 1/3 into the
> area of sharp focus." Is that it? For example, if the lens I'm using has a
> DoF of 6 feet at 100 ft,  would get the best results by focusing at 98 feet?
> With short focal length lenses, I normally just put the subject at the
> closest point that will be in sharp focus, but with a long lens that leaves
> the immediate forground around the subject fuzzy.
> 
> --Gib

The first third in from the front: 37.3 ft. in that case.
Just look at the dept. of field scales on your lens Gib! The one third rule is
for when you don't have time to do that or with a view camera where there is not
depth of field scale and you believe in the one third rule. And it doesn't work
for all lenses. A famous rule that often doesn't work.
I just puled out my 35 Summicron Asph m.
With my 35mm lens to get 5 to 30 feet in focus at F 11 I'm focused at 8 feet.
That's not one third, 13 feet would have been one third not 8. 8 is like one 4th
or 5th in. But with many lenses it would work. You get more in focus behind what
you are focused on then in front is a general enough concept.
Mark Rabiner