[Leica] A photographers law. NEVER BACKFOCUS. Makes for lousy pictures. (long)

[Jim Brick <jim@brick.org>]

At 10:12 PM 12/18/97 -0500, you wrote:
> Subj:	Re: [Leica] Infinity focus tip
>MGMcGough2 says...
>
> 
> > the only way to get the best definition at infinity (or very faraway) is
> > always to focus at infinity. 
> >>
>  Here - Here
>
>  MG
> 

OK... here we go. Last time.

I may seem a little agitated here, but people keep telling me to focus
somewhere else other than where the subject is. And by focusing at
infinity, that far away subject will be in focus. As if hyperfocal theory
doesn't exist. What doesn't exist, in the real world, is infinity. Even
though I've already posted it, look it up in Webster yourself. How the hell
did anybody figure that focusing past your subject is proper? How can
anybody state or imply that the laws of optical physics don't work?

So let me get this straight... if you are going to take a photograph of an
object that is very far away (call it point A), and infinity is at point B.
You are actually telling us that to get the best definition when
photographing point A, you should focus on point B.

Well MGMcGough2, I'm not sure what universe you are from, but here on
earth, focusing on the actual subject that you want in focus, is the way to
go. Trust me. Actually focusing a little in front of it is even better. DOF
law is 1/3 - 2/3. A photographers law. NEVER BACKFOCUS. Makes for lousy
pictures.

Photographers quite often use hyperfocal distance to insure acceptable
focus from near to far. The hyperfocal distance for a 50mm lens is 20' 30'
40' whatever you will accept as the minimum circle of confusion, and is
associated with an f/stop. f/8, f/11, f/16. Now believe me, this is FAR
MORE SEVERE, than just backing off of the infinity stop by a smidge. This
is WAY OFF THE INFINITY STOP. A photographers law. NEVER BACKFOCUS. Makes
for lousy pictures.
Depth of field extends 1/3 forward and 2/3 back from the exact plane of
focus. This is an optical law. The distance depends upon the f/stop and the
lens-to-subject distance. As you start to backfocus (focus beyond the
actual important subject), sharpness up front disappears very rapidly. A
photographers law. NEVER BACKFOCUS. Makes for lousy pictures.

So even if WA and MWA lens manufacturers figure infinity is at some defined
distance, 5000', 10000', whatever, backing off of the infinity stop a
smidge, on a WA or MWA could only improve your photograph, it cannot harm
it. DOF is 1/3 - 2/3. It's the law and cannot be changed. It's just plain
old common sense (and the laws of physics) that you *never* want to focus
at the absolute back of your image. Every competent photographer in the
world knows this. It's called BACKFOCUS and it SUCKS.

Focusing at infinity flies in the face of hyperfocal theory. And you are
permanently backfocused. Bad.

So why am I having so much trouble explaining this?

Since I've rambled on this long, I will continue and define hyperfocal
focusing. Hyperfocal focusing follows the optical laws of physics. I didn't
make it up! This in itself, should show anybody, that focusing on infinity
is dumb.

"When a lens is focused at infinity, the near limit of it's depth of field
(the nearest plane where focus is acceptable),is called the HYPERFOCAL
DISTANCE. If the lens is then refocused on the hyperfocal distance, IT
ACQUIRES A SPECIAL PROPERTY: its depth of field will begin at a point
halfway between the lens and this hyperfocal distance, and extend ALL THE
WAY TO INFINITY. ALL THE WAY TO INFINITY. There are hyperfocal charts for
every conceivable lens, f/stop, and acceptable circle of confusion.


Now go back and read the part that says "IT ACQUIRES A SPECIAL PROPERTY".

Now you tell me, is focusing on infinity smart?

Very very wide angle lenses (75mm for 4x5, 38mm for 6x6, 15mm/19mm for
Leica), have such a great depth of field, you can set the focus almost
anywhere, if you stop down. But you should follow good photography practice
and actually focus on the important subject plane, using the 1/3 - 2/3 law
to insure a super quality product. Or use the hyperfocal distance. For the
15mm Super Elmar, it's 1.9 feet at f/16 with a .001 circle of confusion.
Everything from .95 feet TO INFINITY is in "critical" focus. .95 feet is a
FULL HALF INCH in front of the infinity mark. Imagine that! A FULL HALF
INCH in front of the infinity mark. On a 15mm lens.

I'm through with this subject. This seems like an exercise in absolute
futility. I know from experience what works. And, strangely enough, it
mimics the laws of optical physics. Before anybody says any more, I suggest
you read:

James & Carroll Higgins, "Introduction to Photographic Theory", Wiley
A. E. Conrady, "Applied Optics and Optical design", Dover
Arthur Cox, "Optics, The Technique of Definition", Focal Press
Wall, Jordan, & Carroll, "Photographic Facts and Formulas", Amphoto
John Williams, "Image Clarity, High Resolution Photography", Focal Press

The above dissertation is basically what is taught at Brooks. It's optical
theory. It's the laws of physics. Brooks is correct. They didn't change the
optical laws. And they have produced some really unbelievable world class
photographers. A few that you possibly know are, Dave Chan and Ken Marcus
of Playboy fame. George Lepp, nature photographer, lecturer. Sherman Hines,
very famous Canadian photographer, has published over 50 scenic books and
is one of the founders of Master Stock (I think that's the name).

Jim

ps... this whole exercise is like the camera shop employee who tells people
that you need a Leica enlarging lens to enlarge Leica produced film. A lot
of people will believe it, and defend it to the death, because it was said
by a camera store person. Unbelievable!

Read the above books. Learn about hyperfocal theory. And don't backfocus.

Your Leica glass can produce awesome images, if focused correctly.
Remember, there are many factors that add up to sharp photographs. Clean
Leica glass, no flare, no shake, high res film, and proper focus. So focus
properly and carefully.