DOF scales on Leica lenses outdated in digital era?

[Robert Blanko]

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Howdy,

When using my WATE / Tri Elmar 16/18/21 I experienced that the DOF scale does not seem to be suited for the small pixel pitches of the M10R if you really want to zoom in afterwards. Instead of using the DOF scale for f8 the one for f4 seems more appropriate at f8 (or 5.6 at f11) for really sharp photos within the indicated range.

Did Leica ever change the scale over the last decades which supposedly still originates from good old analogue days and what is the basis for the scale? I think the scale relies on pixel pitch or blur circles of 30 microns. (Did however not find the source again.)

As the M10R has a pixel pitch of about 5 microns, this would possibly explain said discrepancy?

Best,

RB

[earleygallery]

DoF is the range of 'acceptable' sharpness at a given aperture/distance. It's not meant for pixel peeping!

[Jeff S]

One to two stop compensation is not a bad rule of thumb.  More nuanced (albeit a bit wandering) discussion here...

Jeff

Edited May 5, 2021 by Jeff S

[Michael Geschlecht]

Hello Robert,

Welcome to the Forum

You are correct that many Leitz/Leica lenses have used a circle of confusion of 1/30mm for many years. A long time ago many people found this suggested system for providing adequate depth of field in their images to be inadequate. A number of people found that closing down the lens an additional 2 stops produced an image with more useful depth of field. That is: Using an aperture of F8 when the guidelines suggest F4.

By the way, for precise depth of field there needs top be precise focusing. Imprecise focusing takes away a significant portion of the advantage that extended depth of field provides.

Best Regards,

Michael

[Herr Barnack]

Quote

DOF scales on Leica lenses outdated in digital era?

No.  Not in the least.  The DoF scale is crucial for zone focusing. 

Zone focusing may be a forgotten technique for a lot of photographers, but there are some of us who still use it.

[Michael Geschlecht]

Hello Robert,

There is another issue here: When you focus on a subject you are creating a plane of precise focus only at the plane of focus. In front of & behind this plane the image deteriorates progressively more the further from this plane of precise focus that you go. In either direction that you go. Acceptable depth of field is a factor of lens opening and also distance from the film plane to the subject focused on. As you move away from the plane of focus you are effectively "stacking" a series of less & less well focused images in front of & behind the in focus image plane.

Best Regards,

Michael

Edited May 6, 2021 by Michael Geschlecht

[Michael Geschlecht]

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Hello Robert,

There has been a little trouble with the computer here.

In "The Old Days" there was a group of people who thought a lot of the same things that you are thinking. They were using large format film cameras. Not 35mm film cameras. They called themselves "The F64 School". They took photos with their lenses set to F64. Sometimes to F128. Keeping in mind: F1.4, F2,............F11, F16, F22, F32, F45, F64, F90, F128......

You should pick the level of acceptable approximation beyond the sharpness available at the image plane that is what you want it to be.

Best Regards,

Michael

Edited May 6, 2021 by Michael Geschlecht

[oldwino]

1 hour ago, Herr Barnack said:

No.  Not in the least.  The DoF scale is crucial for zone focusing. 

Zone focusing may be a forgotten technique for a lot of photographers, but there are some of us who still use it.

I’ve never found the scales as useful on digital as on film. Digital deems more demanding. 

[Herr Barnack]

20 minutes ago, oldwino said:

I’ve never found the scales as useful on digital as on film. Digital deems more demanding. 

Digital is less forgiving than film when using zone focusing; it's still a useful technique if you take that into account and make allowances for it.

YMMV.

[luigi bertolotti]

Imho, in digital there are two basic factors (the Bayer filter and the RAW development) that alter the classic definition of DOF based on the "circle of confusion" concept... Lenses' manufacturer COULD adpot some new standard... but any choice should be questionable... 🙄 , so I understand that Leica has simply decided not to modify their classic scales.

 

 

[pgk]

Two choices. Makers either engrave a DoF markings based on specific parameters (and in the case of Leica M, Leica still use the same parameters that were used for film, potentially because some lenses are still used on film cameras - so they are 'legacy markings'😉). Or they don't use any DoF markings at all (as many modern AF lenses don't). Given these two possibilities, I think that Leica have taken the right approach by retaining backwards compatilbility with film cameras. Digital users can either use the markings and modify their use based on their experience (the 2 stops wider 'rule' is reasonable enough in many situations) or ignore them. Everybody gains🙂.

[Robert Blanko]

Thanks for your feedback! 
 

As a rule of thumb, the „minus two stops“ rule works well for me. However, I only use this for wide angle lenses. I will also add small markings on my WATE for indicating the hyperfocal distance calculated with a DOF calculator for the respective focal lengths.

Zone focussing is still another story for me, and usually I don‘t use this technique.

[a.noctilux]

In the old days of films, when I used for the first time Kodachrome 25, I was already "upset" by the dof scale on my Summicron 35mm IV.

I know by then that the dof scales was calculated for "average speed film" of 100-400 ASA, even with K64 sometimes the dof could not be fully trusted.

 

My conclusion since then, I don't rely on dof scale marked on lenses.

 

Diffraction limited is a concern though 🤥.

Another thing that I forgot was the decrease in "sharpness" when I closed the lens too far, about f/11-16.

I understood why Leitz lenses were limited in general to f/16 or f/22 ( ...f/32 on very long Telyts ...).

😉

As side note, about diffraction (short user description),

when I used the Apo-Telyt-R 3.4/180mm with my R or Leicaflex, I learn not to close down as the best lens "sharpness" is wide open.

Even now when I use this lens ( or the 280 homonym ) wide open on my M (with LV/EVF), I appreciate the "lack of aperture shape bright spots".

 

 

[Guest]

Peter Karbe talks about this in one of his videos on youtube. The current dof scales are still based on a circle of confusion of 0.03mm. Internally, Leica now works with a circle of confusion of twice the pixel pitch because many current photographers are pixel peepers.

[a.noctilux]

No need to be pixel peeper,

see my post #13 above

we saw/still see the limit of dof scales since we look at projected slides for some decades.

My surprise was when I see dof scale NOT in phase with others (0.03mm)on Super-Angulon 4/21,

far too large !

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comparing to Elmarit-M 21mm

or this Super-Elmar-M 21mm

Edited May 6, 2021 by a.noctilux

[luigi bertolotti]

Yes... I remember that the "SA 21 DOF scale issue"  was discussed time ago... my idea is that its original DOF scale was in turn a "legacy" from some Schneider standard (they were the designers, and providers too, of the original SA 21)

Edited May 6, 2021 by luigi bertolotti

[RoySmith]

9 hours ago, Michael Geschlecht said:

Hello Robert,

There has been a little trouble with the computer here.

In "The Old Days" there was a group of people who thought a lot of the same things that you are thinking. They were using large format film cameras. Not 35mm film cameras. They called themselves "The F64 School". They took photos with their lenses set to F64. Sometimes to F128. Keeping in mind: F1.4, F2,............F11, F16, F22, F32, F45, F64, F90, F128......

You should pick the level of acceptable approximation beyond the sharpness available at the image plane that is what you want it to be.

Best Regards,

Michael

Pinhole Cameras have a nearly infinite DOF and with no lens there is no focusing. 🙂

[adan]

The standard, once DoF scales became a thing at all (no such thing on 4x5/8x10 cameras/lenses - i.e. the first 80 years of photography or so) was what would appear sharp in an 8" x 10" (letter/A4-sized) print, viewed with the unaided eye. And certainly at 4"x6"/A6 "drugstore-print" size.

Museums frowned on patrons pulling out a magnifier and looking at pictures from 10cm/4 inches away.  And advertising billboard-sized images were viewed form 100s of m/feet away. Photographers were a lot less - narcissistic - in how deeply they peered into their own (or each other's) photographs.  

Echo and Narcissus, by John William Waterhouse (link via wikimedia)

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Scale your pictures on-screen so that they are about A4 sized - probably at 8%-16% depending on the camera's Mpixels - and the lens scales are still quite accurate in predicting what will appear to be sharp.

But if you must view your pictures as though they were a 2m x 3m print viewed through a magnifying glass, then yes, stop down 2-3 stops more than the scales recommend.

[Michael Geschlecht]

5 hours ago, Robert Blanko said:

Thanks for your feedback! 
 

As a rule of thumb, the „minus two stops“ rule works well for me. However, I only use this for wide angle lenses. I will also add small markings on my WATE for indicating the hyperfocal distance calculated with a DOF calculator for the respective focal lengths.

Zone focussing is still another story for me, and usually I don‘t use this technique.

Hello Robert,

Additional consideration for depth of field is needed more with longer lenses than it is with wide angle lenses. So, that means that longer lenses need stopping down even more.

Best Regards,

Michael

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Hallo,

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[luigi bertolotti]

Just to chat about DOF... does someone has a memory better than mine ?  I have a vague recollection dating to the times af the 35mm SLR dominance and the related boom of 3rd party lenses.. (40 years ago... probably a little more than less) : one of the well known manufacturers of that era (Vivitar ? Tamron ? Sigma ?) once introduced a "normal" tele (135 or 200) which had the  exclusiveness of an exaggerated top closure (f 64, I'd say)... for the DOF passionates... I think it was an unsuccesful / short-lived product , but am sure it was announced (probably read about it on some photo magazine) ; does someone remember something more precise about ?

Edited May 6, 2021 by luigi bertolotti