Why No Camera Can Focus

jstraw

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Unless you're dealing with a point of focus closer than the lens can focus, the point of focus is somwhere between minimum focus and infinity. The point of focus is, by definition *somewhere* in between. So *some* point is going to be in focus, even if by accident or even if it's not the point you desire. So generally speaking, no matter where the focusing ring or bellows are...*some* point is in focus. If that point can be determined then you can focus at that distance at that adjustment.
 

David A. Goldfarb

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The Messraster sounds a lot like the microprism screen, which I've always found hard to use. I had a microprism spot on my Canon EF, and I've had a few SLRs with microprism rings.
 

Alex Hawley

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Curt said:
http://www.anstendig.org/WhyNoCameraCanFocus.html

Any experience with or comments on this? I did in a workshop given by the, can't mention the government agency, and it was an eye opener.
Click to expand...

To me, its a dead horse argument. What he is saying is true in the strictest respect, but obviously not in the pragmatic respect.

Back when I was navigating a ship, we had a similar saying; you never know exactly where you are, just where you have been. But we still got there and got there safely.
 

Michel Hardy-Vallée

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I find that he spends an inordinate amount of time bombasticly praising his system, disparaging all others, and giving little or no experimental data. I don't care if his system is better, he's so self-sufficient that I distrust this paper.
 

David H. Bebbington

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David A. Goldfarb said:
The Messraster sounds a lot like the microprism screen, which I've always found hard to use. I had a microprism spot on my Canon EF, and I've had a few SLRs with microprism rings.
Click to expand...

His writing is rather impenetrable, but as I understand it he's saying that microprisms are too inexact, with too wide a tolerance either side of true focus before they become really noticeable. This is well known - it is a good idea (if inconvenient) to have a number of interchangeable screens (assuming your camera has this facility) and use the one best matched to your lens (which could be microprisms for large-aperture lenses, a split-image rangefinder/Fresnel for wide-angle lenses, and a plain screen for very long lenses). He repeats the word "Messraster" like a mantra, this is only the normal German word for "graticule" and I can see no reason why an inscribed grid of any kind should be an aid to focusing. In any situation with fantastically high requirements regarding focusing accuracy (mainly scientific applications), standard practice as far as I am concerned would be to use a clear screen (not matted) with an inscribed cross-hair and a high-power magnifier eyepiece. This will give you really accurate focusing (assuming your camera has the viewing plane totally coincidental with the film plane) but also a big headache if you look away from the cross-hair and try to concentrate on pictorial composition. I think Mr. Anstaendig is sadly an obsessive in a world of his own ( as are most people who say "The whole world and the standard practice of the last 150 years are all wrong, only I am right"!).
 

Vaughn

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What an article....

For most of us, 90% of the time it does not matter precisely where the exact plane of focus is. We'll be using depth of field to get acceptable sharpness where we want it. It won't matter if the plane of focus is 15 feet out or 17 feet out -- as long as the depth of field gets the foreground to the background (or infinity) sharp enough for the level of enlargement we want. And determining that is not all that exact. Perhaps I should be more careful, but it seems he is, for the lack of a better way to explain it, talking about the need to measure something in cm's that is actually meters in length.

While there are many exceptions, most photographs do not depend on getting one particular plane in exact focus.

I did enjoy his breakdown of the term "depth of field"...sort of sounded like saying..."What is the English translation for the German word meaning "depth of field"?
 

FrankB

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Well gosh, I suppose I'd better throw these two Rollei 35's away then... :rolleyes:
 

Mick Fagan

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What is it with musicians and photography.

I must be doing something wrong, the only musical instrument I can play is a bell.

Mick.
 

hammy

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I took it serious until this part
I know that's reasonably wrong because it seems with the more experience I gain, the less I am actually wasting film.
 

Alex Bishop-Thorpe

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Ummm, brought to you by the author of Dead Link Removed?

The point of photography is that we don't require an exact point of focus. As long as it looks in focus, we're good to go. Photography, for most of us, is more art than science.
 

jstraw

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To put my point of view another way, I think it's important to think about both focus and resolution. Resolution is affected by a variety of things such as the lens, the film emulsion and how it is developed and the paper emulsion and how it's developed. For any combination of resolution-tempering-factors there is a limit to which perfect focus can be reproduced. Within those limits...point a camera at something...focus on something...even casually and make a picture. Something at some distance will be at the distance of perfect focus whether you know what that thing is or what that distance is. Perfect focus happens. It (within these parameters) cannot be *avoided*.

The ability to adjust the camera to place that point of perfect focus where we want it is what's in question. Pretend for a moment that your equipment offers absolutely no impediment. First of all, the point of perfect focus is subjective. Second of all we don't have perfect eyes, even if it were objective and thirdly, we still can achieve focus *within* the limiting factors of resolution.

So, even if he's right and at the theorhetical level our technology is imperfect, It. Does. Not. Matter. Subjectivity, imperfect eyes and resolution will result in no better result even if we have access to perfectfocusing technology.
 

JBrunner

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People that get worked up about a technical non issue to the point of prostelization like this just need to get out and take some pictures.
If you are that freaked out about focus, just measure it.
 
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Tom Hoskinson

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Astendig's lack of focus was only one example of the effects of destructive interference on the various vibrational influences in his life.

Ahh psuedoscience!!
 
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David A. Goldfarb

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What amateurs do not know is that, in focusing, the only difference between them and the professionals is the amount of film used: the professionals have merely learned not to save film, but rather to shoot as many rolls as possible so that, with luck, they will at least have one reasonably sharp picture that serves their purpose.

This made me laugh! So the "professional" photographers are only considered professional because they shoot more film, in result having better LUCK in getting a good picture that is in focus?

Emagine that! Wow!
 

DBP

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Let's see...

1. He thinks the eye has a memory, albeit fleeting, which I am sure would come as a surprise to all neurologists and opthalmologists.

2. He thinks that rangefinders are inherently limited to focusing on objects closer than 30 meters, having apparently never encountered the other uses of rangefinders or the study of geometry and trigonometry. Thus he does not realize that rangefinders have been used to determine distances of moving earthbound objects to at least 20 miles (e.g. naval rangefinders in the world wars), and celestial objects far beyond that.

3. He thinks a grid on ground glass is used for focusing, which would seem to confirm the implication in his comments about professionals that he does not know the difference between composition and focus.

4. He thinks that focus is achieved in more than one plane (the film and ?).

5. He thinks the poor resolution of TV pictures is due to problems with focus, having apparently never looked closely at a TV screen .

6. It doesn't occur to him that most of the problem with the Zapruder film lies in it having been made handheld on 8mm film.

Wow!
 

StephenS

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I won't waste my time reading some technical jazz, but I always thought the best images were supposed to be out of focus. Isn't that why you're supposed to breath on the front of the lens before each exposure? That's what all the Kodak books say to do.
 

JohnArs

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Out of focus or autofocus?!! Does it matter?¨'?!!
The bummble-bee does not know that she can't fly by physical law, but she does'nt know this laws and just flying around!
I think the film flatness in the holder is more a problem then any focusing problem!
Happy New Year, Armin
 

JohnArs

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And yes I can do it with a Satinsnow and even with my old Sinar glass!
Because I did not know it was impossible, but since I know I get a hard time in focusing!¨¨''???
Just take pictures!
 

Jim Jones

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Now I know why Ansel Adams photos always seemed so fuzzy. Poor Ansel! All that work for fuzzy photos! I thought I just needed new glasses. Mr. Anstendig has cleared it up, and saved me a trip to the optometrist.
 
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