Range Finder Focusing - Not as described

[MikeMyers]

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I enjoy watching "how-to" videos about things I don't yet understand, and did so years ago for my then new M8.2 and am doing so again for my M10.  Lots of videos, and so many of them make s very simple mistake when they describe focusing.

They talk about depth of field, and say something like "everything from ten feet to thirty feet will be in focus at this aperture.  The problem is, that is NOT correct.  If you focus your lens at say, 13 feet, ONLY objects at 13 feet will be in focus.  Objects closer or farther away will NOT be in focus.

What these books and articles should say, is that "everything from ten feet to thirty feet will APPEAR to be in focus.  Big difference.  It all has to do with the viewing distance, and how large the image will be as it is being viewed.

 

If I remember correctly, the definition was something like viewing an 8" x 10" print , held out by your hands in front of you. Something like that.

 

All of this falls apart if the image you are viewing is larger or small er than expected, and what distance it is being viewed at.  Things that appear to be in focus on a full frame print, will likely appear to be out of focus if you crop the original image, meaning the small part of the image you're now looking at is enlarged much more.  Or, if you take a photo and make a large six-foot banner, perhaps for an exhibition hall.  On the other hand, if you were to take the image and make it into a post card, everything in the image is likely to look in focus.

 

For a camera as good as the Leica, with high quality lenses which are typical of Leica, all these things need to be considered.  If you're just doing "street photography", maybe it doesn't matter very much, but if you're taking a photo that you intend to make into a wall-size mural, there's a lot more to be considering than just the camera's "depth of field scale".  And if you're going to crop the image, perhaps in-camera using a M8.2, or in your photo editor, this becomes even more important.

 

This is probably the wrong forum to post this, but chances are, anyone new to rangefinder photography won't know about this, and will get the wrong impression from reading or watching the books and videos about focusing.

[adan]

That is a very good description of reality. DoF is what appears to be in focus, at a specified print size (as you say, generally 8x10, 8x12, or A4).*

My only quibble is that this has nothing to do with range finder focusing as such.

It is true of any and all focusing with any and all systems. RF, EVF, SLR ground-glass, SLR "split-image" screen, view-camera ground-glass, "live-view," "guess-focus," and autofocus.

I remember my first attempt using an old wooden 8x10 view camera. Set up a trial shot down 300m of street with a normal (for 8x10) 300mm B&J lens, said to myself "Let's see, the "everything sharp" school of photography in the 1930s (the Westons, Ansel Adams, etc.) called themselves "Group f/64", so let's use f/64."  Set focus at about 1/3rd down the street, tried to check DoF with the lens stopped down to f/64 (far too dark to really see anything), metered, set shutter speed, shot.

I got about 50m of the street in focus - even in just a contact print. Background and foreground were fuzzy. Should have used at least f/128 (and/or used some Scheimpflug lens tilt).

Yes, engraved DoF scales are based on the assumption of a fairly small print (on those lenses that still even bother with DoF scales!).

It has been suggested that with the amount of detail that can be captured on digital sensors, they are too optimistic even for 8x10s - they count on the general fuzziness and/or deeper focal plane (emulsion) of film to extend the "looks as sharp as anything else in the picture" zone. And thus one needs to stop down 1-2 stops from what the scale reads even for moderate print sizes - and even more if planning a larger print (16x20/A2 plus).

____________________________

*8x10/A4/"letter" prints were, in fact, the fairly universal standard for photography for quite a long time, with the occasional 11x14 (size of a LIFE or LOOK magazine page). Remember your Alice's Restaurant Massacree:

"They took twenty-seven eight-by-ten color glossy photographs, with circles
and arrows and a paragraph on the back of each one explaining what each
one was, to be used as evidence against us. Took pictures of the approach,
the getaway, the northwest corner, the southwest corner, and that's not to
mention the aerial photography."

[sblitz]

3 minutes ago, adan said:

That is a very good description of reality. DoF is what appears to be in focus, at a specified print size (as you say, generally 8x10, 8x12, or A4).*

My only quibble is that this has nothing to do with range finder focusing as such.

It is true of any and all focusing with any and all systems. RF, EVF, SLR ground-glass, SLR "split-image" screen, view-camera ground-glass, "live-view," "guess-focus," and autofocus.

I remember my first attempt using an old wooden 8x10 view camera. Set up a trial shot down 300m of street with a normal (for 8x10) 300mm B&J lens, said to myself "Let's see, the "everything sharp" school of photography in the 1930s (the Westons, Ansel Adams, etc.) called themselves "Group f/64", so let's use f/64."  Set focus at about 1/3rd down the street, tried to check DoF with the lens stopped down to f/64 (far too dark to really see anything), metered, set shutter speed, shot.

I got about 50m of the street in focus - even in just a contact print. Background and foreground were fuzzy. Should have used at least f/128 (and/or used some Scheimpflug lens tilt).

Yes, engraved DoF scales are based on the assumption of a fairly small print (on those lenses that still even bother with DoF scales!).

It has been suggested that with the amount of detail that can be captured on digital sensors, they are too optimistic even for 8x10s - they count on the general fuzziness and/or deeper focal plane (emulsion) of film to extend the "looks as sharp as anything else in the picture" zone. And thus one needs to stop down 1-2 stops from what the scale reads even for moderate print sizes - and even more if planning a larger print (16x20/A2 plus).

____________________________

*8x10/A4/"letter" prints were, in fact, the fairly universal standard for photography for quite a long time, with the occasional 11x14 (size of a LIFE or LOOK magazine page). Remember your Alice's Restaurant Massacree:

"They took twenty-seven eight-by-ten color glossy photographs, with circles
and arrows and a paragraph on the back of each one explaining what each
one was, to be used as evidence against us. Took pictures of the approach,
the getaway, the northwest corner, the southwest corner, and that's not to
mention the aerial photography."

Now that brings back a happy memory or two or three!!!!!!!

........ exceptin' Alice ....

 

 

[adan]

Anyway - I can't even remember that last time I looked at a DoF scale. It's just not how I make pictures. I'm usually concerned with the one thing that needs to be sharp, and everything else can just lie where it falls, according to the aperture required by the light, and the focal length.

I guess I'm just influenced by W. Eugene Smith. After recovering from his WW2 wounds, he threw out all his pre-war pictures.

When asked why, he said "Great depth of field. No depth of feeling!"

I prefer pursuing the feelings (moments, expressions, gesture.) I find it pays off better, both in personal satisfaction and prints sales, than pursuing the perfect DoF.

I can remember that last time I looked at the focus scale - Feb. 5, 2020 - when I set 1m on the 28mm to capture this literal "over-the-shoulder" shot (that's my shoulder on the right).

Bobbie, M10, 28 Elmarit ASPH

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[pgk]

Depth of Field (DoF) is one of the least well explained topics in photography. Its actually about perception. What we perceive to be 'sharp' IS sharp. This will vary and depends on many more factors than simply aperture and point of focus and some ill-defined rather arbitrary and out of date definition of how we view a specific print. And sharpness itself is a tricky to ermine topic. In this month's Photographic Journal there are several examples of images which are not as 'sharp' as they could be due to point of focus, aperture selected, motion and probably what they were shot on (P160, P191 & P216 if anyone has a copy). In no case does this detract from the photograph leaving me to suggest that as an end in itself 'sharpness' is not always as essential as we think it is, and DoF is, to a variable extent, somewhat incidental to many images. For great enlargement of a suitable subject it is important though, and such images need to be shot in very different ways and are not about relying solely on DoF scales on the camera. DoF scales are guidance.

[Rick in CO]

This reminds me of an article about extreme wide angle lenses in the magazine View Camera (if I remember correctly). 

The author the article recalled testing a new series of lenses and came to the initial conclusion that they were not very good.

Upon hearing this, the company rep asked if he "focused in at the hyperfocal distance" for his test shots.

I've tried this for landscape shots and it works pretty well to get overall apparent sharpness with wide angle lenses.

Otherwise, as pointed out above, get the subject in sharp focus and use aperture selection to get the desired effect.

Selective sharpening in Photoshop helps, when necessary, but does not always yield a satisfactory result.

 

[adan]

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11 hours ago, adan said:

I got about 50m of the street in focus - even in just a contact print

I should, of course, have said I got 50m of the street apparently in focus.

[pixie]

Never forget that "depth of Field" scales on lens are for 5" x 7" print!

Barnack made calculations with friend who designed lens for 1st Leica..

The bigger the print, the less in focus.

 

[jaapv]

8 hours ago, pgk said:

Depth of Field (DoF) is one of the least well explained topics in photography. Its actually about perception. What we perceive to be 'sharp' IS sharp. This will vary and depends on many more factors than simply aperture and point of focus and some ill-defined rather arbitrary and out of date definition of how we view a specific print. And sharpness itself is a tricky to ermine topic. In this month's Photographic Journal there are several examples of images which are not as 'sharp' as they could be due to point of focus, aperture selected, motion and probably what they were shot on (P160, P191 & P216 if anyone has a copy). In no case does this detract from the photograph leaving me to suggest that as an end in itself 'sharpness' is not always as essential as we think it is, and DoF is, to a variable extent, somewhat incidental to many images. For great enlargement of a suitable subject it is important though, and such images need to be shot in very different ways and are not about relying solely on DoF scales on the camera. DoF scales are guidance.

Explaining it well doesn't help, I'm afraid...

[mujk]

I think it has been fairly well explained e.g. here:

https://en.m.wikipedia.org/wiki/Depth_of_field

The problem is just that it's dependent on perception, which is very subjective and hard to measure.

[Pyrogallol]

To confuse it more, I thought it was all about the “circle of confusion” the lens designers felt acceptable for the print size imagined when they decided what depth of field scales to put on lenses. I think I read that Leitz were more critical than others in their settings?

also I find that some discussions confuse depth of field with depth of focus. “Field” is in the field in front of the camera, “focus” is at the film or sensor position where the lens projects the image being recorded.

Edited February 27, 2020 by Pyrogallol

[Ko.Fe.]

Just take it easy. In focus, means not blurred, a.k.a sharp and it is not just where you focused.  It is 2020 and everyone should look and learn how to use something like this by now :

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

This is how I was able to determine what is going to be in focus then I stopped to take pictures by just using of  AF

Honestly...

Here is really nothing too complicated to explain, make long videos and brush it as mystery.

As long as you have Leica made RF lens or similar to it lens, it is easy. I explained it to young colleague in two minutes.

Here you go:

 

Put RF lens on the camera. Put camera via neck strap on the neck. Look down at the lens. 

You will see aperture scale at far end the lens, closer to the filter, hood. It shows aperture numbers for you to select for exposure.

Then, in the middle you will see focus distance scale. It will show you at which distance you have focused.

And then, closer to camera - DOF scale. You don't even need to know what DOF is. Just look at the aperture set on first ring, then find same number on DOF scale. It is shown twice. Everything in between  those two aperture marks is in focus at distance shown on the focus scale.

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Aperture set on f8. Lens is focused by RF on 3 meters. Looking at dof scale (bottom), finding 8 left and right. Looking up left 8 on the bottom is near 2 on the middle. Right 8 on the bottom is near 5 on the middle scale. Read as: with aperture set at 8 and with RF focus at 3 meters, everything between 2 and 5 meters is in focus (sharp, not blurred).

Reminder, if shutter speed is slow and object is moving it might not be in focus. Also do not use it if you are in the moving train :).

 

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 I wrote it so many times here, use this method and focus tab for zone focusing without even looking at the lens and without using of rangefinder. All you have to do is check aperture number and focus, dof scales to determine where focus tab needs to be for near, middle and far focus. 

 

 

[mujk]

The problem is that, as already mentioned, the image is absolutely sharp, or absolutely in focus if you like, only at the plane of focus. All subjects not at this plane (which with some lenses may actually be curved and not flat) are more or less out of focus. The DoF concept just defines what is acceptable blurriness, i.e how large the circle of confusion may grow while still being perceived as a point of light. There are different conventions for how this perceived sharpness is defined. The wikipedia article explains this quite well. Leica (and other) lenses with a DoF scale are calibrated according to a fairly "loose" convention, created in the days of film. With today's high-resolution lenses and sensors you will clearly see blurriness for subjects inside this DoF bracket, particularly when enlarging the image more. So in these cases the DoF scale cannot be trusted.