Minimum focusing distance and zone of focus...

[aesop]

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    ...quick question from an M film-only user:

If the minimum focusing distance of my lens is, say, 0.3m, and I focus on my subject at that minimum distance BUT then stop my lens down to, say, f22, would my zone of focus ultimately be limited by the minimum focusing distance of the lens?

In other words, for a given lens, once I focus on the minimum focusing distance of 0.3m, does 0.29m (or less) remain out of focus, irrespective of the aperture in use?

Thanks in advance.

[Guest]

Sorry I don’t have an answer, but would be very interested to hear what others think/know.

Personally, I would say a minimum focus distance is a minimum focus distance, anything between the camera and subject would be out of focus.

Just my thoughts

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[a.noctilux]

Have a look at your lens' dof scale, you will see that the dof are in both sides (near and far).

If you focus at 30cm, and let's say the other dof scale at f/22 is at infinity (for example) the whole dof would extend from 1/2 of 30cm (15cm in theory) to infinity.

Of course, circle of confusion is 0.033mm if the lens is Leica M/LTM type.

Edited July 14, 2022 by a.noctilux

[lct]

When closing aperture, DoF widens not only in the background but also in the foreground as you know. In the example below, the subject matter is acceptably sharp from 0.26m to 0.35m at f/22. Those are just approximations though as some lenses have more DoF in the background and less so in the foreground, or vice-versa.

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[jaeger]

zone focus at 0.3m @/f22 🤪

[luigi bertolotti]

Sorry... but as a M film user, the real problem is how to focus a subject at 0,3 m... 😉 supposed your lens does reach that focus distance, how do you measure it ? The M rangefinder goes to 0,7m minimum.... are you equipped with a Visoflex unit ? (wouldn't be strange... I used it for lot of years...)

About the basic question   "for a given lens, once I focus on the minimum focusing distance of 0.3m, does 0.29m (or less) remain out of focus, irrespective of the aperture in use?", see this simple article : https://en.wikipedia.org/wiki/Depth_of_focus : apart theory, a definite statement is "...depth of focus increase with smaller apertures..."  and that is always true. 

 

Edited July 14, 2022 by luigi bertolotti

[lct]

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Maybe the OP owns this superb lens:

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[aesop]

On 7/14/2022 at 1:00 PM, OThomas said:

Sorry I don’t have an answer, but would be very interested to hear what others think/know.

Personally, I would say a minimum focus distance is a minimum focus distance, anything between the camera and subject would be out of focus.

Just my thoughts

 

       ...thanks for this, OThomas.

 

[aesop]

On 7/14/2022 at 4:12 PM, luigi bertolotti said:

Sorry... but as a M film user, the real problem is how to focus a subject at 0,3 m... 😉 supposed your lens does reach that focus distance, how do you measure it ? The M rangefinder goes to 0,7m minimum.... are you equipped with a Visoflex unit ? (wouldn't be strange... I used it for lot of years...)

About the basic question   "for a given lens, once I focus on the minimum focusing distance of 0.3m, does 0.29m (or less) remain out of focus, irrespective of the aperture in use?", see this simple article : https://en.wikipedia.org/wiki/Depth_of_focus : apart theory, a definite statement is "...depth of focus increase with smaller apertures..."  and that is always true. 

 

   

       ...not entirely sure what this means within the context of my original query, luigi bertolotti.

Re: "...depth of focus increase with smaller apertures...", I agree with your theory. are you saying that, with focus at 0.3m, stopping down to f/22 could bring 0.29m, 0.28m and 0.27m (etc.) into focus? The Wikipedia link leads to just another rabbit hole and I am not clever enough to navigate.

My simple question remains, though. Thanks.

 

 

 

[Erato]

FYU.

See also:

https://www.photopills.com/calculators/dof-macro

 

 

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[lct]

I thought i answered above. Did i miss something?

 

[farnz]

On 7/14/2022 at 12:44 PM, aesop said:

 

    ...quick question from an M film-only user:

If the minimum focusing distance of my lens is, say, 0.3m, and I focus on my subject at that minimum distance BUT then stop my lens down to, say, f22, would my zone of focus ultimately be limited by the minimum focusing distance of the lens?

In other words, for a given lens, once I focus on the minimum focusing distance of 0.3m, does 0.29m (or less) remain out of focus, irrespective of the aperture in use?

Thanks in advance.

No, the MFD wouldn't wouldn't limit the focus because at, say, f/22* Hyperfocal Distance will take over although it will be 'acceptably sharp' (depending on the Circle of Confusion chosen) rather than the sharpness you would expect for fully in-focus objects.  To maximise focus sharpness use Hyperfocal Focussing.  *Also remember that a tiny aperture like f/22 will cause sharpness to reduce through DIffraction so it would be better to limit the aperture to f/16 to prevent Diffraction working against Hyperfocal Focussing.

 

Hi, Aesop, it's been a long time!  I think the last time we met was in a Chinese restaurant in London after a forum meet many years ago.

Pete.

[scott kirkpatrick]

The only ways to focus the M APO 35 closer than 0.7 meters are (1) tripod plus tape measure, or (2) slap on the excellent VF2 viewer, or look at the rear LCD, and switch on liveview.  This works best on an M11 but can be done on an M10.   I favor (2), and if I want to get a flower or some other small object close and in focus, I usually rock back and forth on my heels, trying to shoot when things are sharpest.  I suppose (3) guess the distance, is also possible.

When I set my APO 35 to focus at 0.3 m, and aim it at my monitor in LiveView at highest magnification, I can see the pixels of the monitor screen when things are in focus  The DOF is only a mm or so at f/2.0 and maybe a centimeter or so at f/8.  I wouldn't stop down further.  f/22 isn't offered, but f/11 and 16 are possible.

 

Edited August 18, 2022 by scott kirkpatrick

[aesop]

8 hours ago, lct said:

I thought i answered above. Did i miss something?

 

    ...no, you didn't, lct. All is well now. Thanks for your response.

[aesop]

5 hours ago, scott kirkpatrick said:

The only ways to focus the M APO 35 closer than 0.7 meters are (1) tripod plus tape measure, or (2) slap on the excellent VF2 viewer, or look at the rear LCD, and switch on liveview.  This works best on an M11 but can be done on an M10.   I favor (2), and if I want to get a flower or some other small object close and in focus, I usually rock back and forth on my heels, trying to shoot when things are sharpest.  I suppose (3) guess the distance, is also possible.

When I set my APO 35 to focus at 0.3 m, and aim it at my monitor in LiveView at highest magnification, I can see the pixels of the monitor screen when things are in focus  The DOF is only a mm or so at f/2.0 and maybe a centimeter or so at f/8.  I wouldn't stop down further.  f/22 isn't offered, but f/11 and 16 are possible.

 

       ...thanks  for this, scott kirkpatrick - sounds like I might soon be in the market for a digital M body. Urgh.

[aesop]

6 hours ago, farnz said:

No, the MFD wouldn't wouldn't limit the focus because at, say, f/22* Hyperfocal Distance will take over although it will be 'acceptably sharp' (depending on the Circle of Confusion chosen) rather than the sharpness you would expect for fully in-focus objects.  To maximise focus sharpness use Hyperfocal Focussing.  *Also remember that a tiny aperture like f/22 will cause sharpness to reduce through DIffraction so it would be better to limit the aperture to f/16 to prevent Diffraction working against Hyperfocal Focussing.

 

Hi, Aesop, it's been a long time!  I think the last time we met was in a Chinese restaurant in London after a forum meet many years ago.

Pete.

     ...Lawd, farnz, you are so right! I vaguely remember trundling through Highgate Cemetery and its immediate environs (on a bitterly cold Marxist morning?) and tucking into some hot food down in Chinatown much later. Trust all is well with you.

Thanks for the technical response - a digital M would have resolved my issue in a trice IF I could be flipping bothered. Anyhows, the forum came to my rescue, so it's 'chocks away'. All the best.

[Cthulhu]

On 7/14/2022 at 6:44 PM, aesop said:

for a given lens, once I focus on the minimum focusing distance of 0.3m, does 0.29m (or less) remain out of focus, irrespective of the aperture in use?

 

Have you tried it? It sounds like one of those things you can just answer by yourself. 
 

f22 should be banned 😀

Edited August 18, 2022 by Cthulhu

[lct]

2 hours ago, Cthulhu said:

f22 should be banned

Any plan to ban macro too?

[jankap]

On 7/14/2022 at 1:44 PM, aesop said:

 

    ...quick question from an M film-only user:

If the minimum focusing distance of my lens is, say, 0.3m, and I focus on my subject at that minimum distance BUT then stop my lens down to, say, f22, would my zone of focus ultimately be limited by the minimum focusing distance of the lens?

In other words, for a given lens, once I focus on the minimum focusing distance of 0.3m, does 0.29m (or less) remain out of focus, irrespective of the aperture in use?

Thanks in advance.

No, of course not. Please understand, that your lens at the focussing distance (fd) gives the best sharpness of your lens. In front of and behind of this distance the sharpness gradually decreases. That means, that close to the fd one does not see very difference, farther away (in both directions) the sharpness decreases. So perhaps (I guess)  at 25 and 40 cm -taken at f22- most people would say the picture is sharp still. Until the distances of the zone focussing are reached. At those, observers will say a handheld picture of A3 is still sharp. But for the same print at A2 they will say -handheld- the picture is not sharp, but who handhelds a picture A2. Here starts the working of the distance observer to picture. Look at an advertising picture (beer, mode or what ever) in your town at close distance, the result is not sharp. But seen at 5 meters it is sharp.

In short, the zone focus marks are only calculated. Not shown on the lens they are at 20 or 15 cm too. The camera ignores them; totally😁.

Edited August 18, 2022 by jankap

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