Zone focus, is everything really in focus?

[Landberg]

Hi!

Zone focus, is everything really in focus? If i focus my 28mm elmarit 1.5 meters (5 fett) then using the scale (at f16) everything between 0.8 meters to infinity is in focus. But is that true? Is it all sharp or is everything kind of in focus but its sharp at 1.5 meters? I only have a film Leica so before i test it myself i was wondering if there is a simple answer?

 

[wolves3012]

I think you're referring to hyperfocal distance rather than zone focus. Logically, zone focus means focussing in such a way that everything within a zone is sharp. At hyperfocal distance that zone extends to infinity, so there's a bit of an overlap in terminology.

To answer the question though, it's no, everything isn't sharp. It's sharpest at the focussed distance (1.5m in your example). However, the idea is that everything from 0.8m to infinity is acceptably sharp, with the emphasis on acceptably. It's worked out based on a few assumptions, like average eyesight and average sized print viewed from a normal distance. If any of the assumptions is false, all bets are off. Besides, consider in your example what happens at 0.799m, it isn't suddenly blurred at 0.799m is it? There's a transition from "acceptably sharp" to "distinguishably not sharp" that begins from 0.8m and closer.

 

[Ko.Fe.]

So you have film Leica, do you have film? If so, get camera fixed to something, usually it is tripod for cameras (cheap one will do). Focus it at the distance you described and with aperture you have mentioned. Take picture (under right exposure) by shutter release cable or release delay if yours M have it. This will give you most correct answer.

Another method is http://www.dofmaster.com/dofjs.html
At f16, 28mm and 1.5 the DoF is 14.4 m with far distance of acceptable sharpness at 15.2 meters 🙂

 

[Landberg]

I think you're referring to hyperfocal distance rather than zone focus. Logically, zone focus means focussing in such a way that everything within a zone is sharp. At hyperfocal distance that zone extends to infinity, so there's a bit of an overlap in terminology.

To answer the question though, it's no, everything isn't sharp. It's sharpest at the focussed distance (1.5m in your example). However, the idea is that everything from 0.8m to infinity is acceptably sharp, with the emphasis on acceptably. It's worked out based on a few assumptions, like average eyesight and average sized print viewed from a normal distance. If any of the assumptions is false, all bets are off. Besides, consider in your example what happens at 0.799m, it isn't suddenly blurred at 0.799m is it? There's a transition from "acceptably sharp" to "distinguishably not sharp" that begins from 0.8m and closer.

Thanks thats what i thougt. I have been shooting Leicas for many years but always used the the rangefinder to focus, i never tried the zone/hyperfocal distance. Didnt know if i could trust it.

 

[Landberg]

So you have film Leica, do you have film? If so, get camera fixed to something, usually it is tripod for cameras (cheap one will do). Focus it at the distance you described and with aperture you have mentioned. Take picture (under right exposure) by shutter release cable or release delay if yours M have it. This will give you most correct answer.

Another method is http://www.dofmaster.com/dofjs.html
At f16, 28mm and 1.5 the DoF is 14.4 m with far distance of acceptable sharpness at 15.2 meters 🙂

Thank you for your answer. But as i wrote, before testing i wanted to know if there is a correct answer.

 

[wolves3012]

Thank you for your answer. But as i wrote, before testing i wanted to know if there is a correct answer.

The correct answer, like so many things in photography, is "it depends". If you have above-average eyesight, if you view the print too closely or use a loupe, if your exposure is wrong and the print is grainy, if the lens isn't exactly as specified and so on, you might not agree with the scale on the lens. Oh, and the scales on lenses can be a bit optimistic in the first place. If you want to leave room for error, use the scale for the aperture one stop wider than your actual aperture.

 

[Bob Michaels]

Zone focus, is everything really in focus?.................. Is it all sharp or is everything kind of in focus but its sharp at 1.5 meters? ..................

No, there is only one point of exact focus. But there is a range, Depth of Field, where everything is so close that any out of focus errors don't show because of lens resolution, film or sensor resolution, enlargement factors, and other things. How close "So close that the differences cannot be discerned" is determined by the numbers used for the "circle of confusion". See
https://en.wikipedia.org/wiki/Circle_of_confusion

Remember that optical design is basically a series of compromises.

 

[zian]

Just go and experiment...

 

[Richard G]

Have a look at this thread. There are a couple of mentions, one by me, of "infinity focus".

http://www.rangefinderforum.com/forums/showthread.php?t=159547&highlight=Depth+of+field

 

[zuiko85]

Years ago, in Shutterbug magazine, Roger Hicks wrote a excellent article about depth of field and DoF scales on lenses. Don't know if it's available to read online but if so would highly recommend the OP look at it. Lots of good information.

 

[rogue_designer]

It depends. Largely on print size (and its relation to sensor size - overall enlargement factor).

As has been said "acceptably sharp" but there are lots of variables. You will learn what is acceptable to you, with experience.

 

[Roger Hicks]

It depends. Largely on print size (and its relation to sensor size - overall enlargement factor).

As has been said "acceptably sharp" but there are lots of variables. You will learn what is acceptable to you, with experience.

Exactly. It's a meaningless question. What is acceptable? To whom? At what enlargement size and viewing distance?

Cheers,

R.

 

[monopix]

Exactly. It's a meaningless question.

No question is meaningless Roger and I would have expected better coming from you. At the very least it means the person asking the question doesn't know the answer and, if it seems a daft question to you, then it means they probably don't understand the subject well enough to know how to ask the question. Every question deserves an answer - we all were novices once - and your response isn't helpful. You'd be better to not bother.

 

[monopix]

before i test it myself i was wondering if there is a simple answer?

No simple answer as you've probably realised.

I would recommend reading The Ins and Outs of focus by Harold Merklinger. You can read it/download it at http://www.trenholm.org/hmmerk/TIAOOFe.pdf

Not everyone would agree with his recommendations but he does explain the issues and has some good examples.

 

[Roger Hicks]

No question is meaningless Roger and I would have expected better coming from you. At the very least it means the person asking the question doesn't know the answer and, if it seems a daft question to you, then it means they probably don't understand the subject well enough to know how to ask the question. Every question deserves an answer - we all were novices once - and your response isn't helpful. You'd be better to not bother.

No, you're wrong. You're not going to like that answer, either. Building on rogue_designer's earlier response I explained WHY it was a meaningless question: "What is acceptable? To whom? At what enlargement size and viewing distance?"

How is that not helpful? Assuming that the OP is not an idiot, he can reflect on acceptability, enlargement size and viewing distance.

A meaningless question is not the same as a daft question, if you can explain to the person asking it why it is meaningless. So don't try to patronize me by "expecting better". You may not have liked the way I phrased it, but that's your problem, not mine.

Cheers,

R.

 

[Dektol Dan]

Focus Rule

Focus Rule

I was taught in school that the focus rule is '1/3 in 2/3 out' for best depth of field no matter how wide the aperture setting is. That's another common rule for beginners like 'keep the sun behind and over you shoulder'.

I never have problems with flare or focus.

 

[Godfrey]

Zone focus, is everything really in focus? If i focus my 28mm elmarit 1.5 meters (5 fett) then using the scale (at f16) everything between 0.8 meters to infinity is in focus. But is that true? Is it all sharp or is everything kind of in focus but its sharp at 1.5 meters? I only have a film Leica so before i test it myself i was wondering if there is a simple answer?

The scale on your lens presumes an 8x10 reference print size and normal viewing distance (around 18" between eyes and print). As has been said, everything in the indicated zone will be 'acceptably sharp' to the eye, but the sharpest capture in the scene will be those things that are at the set focus distance (1.5m). Anything closer or further away will be slightly less sharp, slowly degrading as you reach the limits of the 'acceptably sharp' range.

How sharp is 'acceptably sharp'? You can only gain that knowledge from experience. You might find that a bit more is acceptably sharp to your eye, or a bit less. Once you get a feel for how the focus zone renders sharpness/unsharpness as you move in and out of the critical plane of focus, you'll find it to be completely reliable—modifying the settings and interpreting the indicated zone to suit your personal predilections and printing needs.

G

 

[monopix]

No, you're wrong. You're not going to like that answer, either. Building on rogue_designer's earlier response I explained WHY it was a meaningless question: "What is acceptable? To whom? At what enlargement size and viewing distance?"

How is that not helpful? Assuming that the OP is not an idiot, he can reflect on acceptability, enlargement size and viewing distance.

A meaningless question is not the same as a daft question, if you can explain to the person asking it why it is meaningless. So don't try to patronize me by "expecting better". You may not have liked the way I phrased it, but that's your problem, not mine.

Cheers,

R.

You really don't get it do you Roger and your arrogant answer "your wrong" goes no way to persuading me otherwise. I'm not wrong - you are.

"he can reflect on acceptability, enlargement size and viewing distance."

Not if he doesn't understand how these things affect dof and you have done nothing to help him understand.

Seems you think you are God's gift to all photographers and anything you say must be correct and should anyone disagree, then they must be wrong. Well that ain't the way it is Roger.

 

[bsdunek]

As I recall, and I would have to search for my old Photo Technology book, the depth of field scales are based on a 0.03mm Circle of Confusion. That means, worst case, a point source would cause a "blurry" circle 0.03mm diameter on the film. That's 0.0011811 inches - just over one thousands. So, how sharp is that? Depends on the magnification of the print. If you make 8X10's from a 4X5 negative, that point is about 0.12mm/ 0.004 in. dia. If you make a 16X20 from a Minox negative, well, that's another story. Understanding this, you can take the film size you're using, consider the print size you wish to make, and make a decision. If it's a big print from small film, don't use all the depth of field, and vise versa.

 

[Roger Hicks]

You really don't get it do you Roger.. . .

You really don't get it, do you monopix? Your answer is exactly the sort of thing I was expecting.

Which bit of "acceptable" is hard to understand? Who has not noticed that a big picture, looked at from close up, doesn't look as sharp as a smaller picture viewed from further away?

No, I don't think I'm "God's gift to all photographers". I am however confident that I know quite a lot about photography, and as countless people will confirm, I usually try to answer questions to the best of my ability, within the normal constraints of time and space.

You don't like the way I answered the question. Tough. I'd be upset if the criticism had come from the OP, but it didn't. It came from someone who thought it more important to attack someone who was trying to help, rather than to try to throw any light himself on the OP's question-- or to add anything to rogue_designer's post.

If you can help the OP, then why not try to answer the question? Or indeed, to suggest that I might enlarge upon my answer? I preferred to assume that the OP could think for himself, and might soon understand why it's a meaningless question.

Cheers,

R.