Depth of field Summicron 50 V3

[Miers]

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I have a film MP (latest version ) camera  and Summicron 50 V3 lens. I  am trying to get as much foreground as I can with infinity horizon in some landscape photographs. But I have some confusion about difference  between lens scale setting and focusing in the viewfinder . They don't agree .

When I set f16 at 250th and align infinity with central marker the scale indicates 5 metres out of focus in the foreground . But when look through the view finder the foreground out of focus is much further than that . Perhaps as much as 30 metres or more . Which do I trust : the focus through the view finder or the lens scale ? There is a difference.

I am using 200 ASA fuji  negative film

Thanks in advance

Robert

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[TomB_tx]

Sharpest focus is only at the distance at the center mark on the lane scale - the depth-of-field marks indicate "acceptable sharpness" over the range between the marks - but that "acceptable" is based on a medium-sized print at normal viewing distance. To get the most usable DOF from infinity at f16, set the infinity mark at the f16 line to the right of the lens scale. The left mark should show acceptable sharpness to a bit under 3 meters. You may do better to focus closer and let the infinity distance go a bit less focused.

Also, f16 will give a somewhat softer image even in the sharpest distance due to diffraction from the small aperture - but sometimes that's OK to get the DOF you want. Most lenses are sharpest at the plane of focus around f5.6 - but we take a lot of pictures at smaller apertures when the DOF is needed.

Edited November 1, 2024 by TomB_tx

[Erato]

These info might be useful to you, FYR.

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Leica M Rangefinder Focusing Tips and Tricks -- via RedDotForum

Timestamps
===================
0:00 - Intro
0:22 - What is a rangefinder
1:15 - Tip 1: Keep things clean
2:15 - Tip 2: Use hyperfocal distance
4:33 - Tip 3: Try zone focusing
6:09 - Tip 4: Pick the right focal point
7:41 - Tip 5: Estimate distance
11:10 - Tip 6: Learn focus ring positions
13:52 - Tip 7: Use your body to fine tune focus
16:15 - Conclusion

[Michael Geschlecht]

Hello Robert,

Welcome to the Forum.

The image you see thru the range/viewfinder window is an approximation of what the lens is capturing as delineated by the frame lines for the lens in use. This view is not a reliable representation of the depth of field of the lens in use & it should not be used for that purpose.

Additionally:

On many lenses of varying focal lengths depth of field indicators on the lenses that you look at directly are an approximation of the depth of field that is acceptable for general purposes.

Some people who use these indicators use a more critical standard for sharpness, where, for example:

If you want sharper pictures than the indicated settings suggest: You might set your lens to (For example.) f16

And then figure the depth of field at the measuring point for a lens aperture that is set TWO stops LARGER.

Meaning: Use the distances for f8.

And: If you want to have an even more fine tuned depth of field: You would then refocus the image so the point of focus is set at the place where the most important aspects are within the depth of field lines when the lens is set at f8.

While leaving the lens set at f16.

And setting the exposure for f16.

Best Regards,

Michael

Edited November 1, 2024 by Michael Geschlecht

[Miers]

Thank you to all who relied; I'm grateful ' 

I do have a clearer picture (ha ha ) of depth of field now.

[250swb]

On 10/31/2024 at 11:53 PM, Miers said:

 

When I set f16 at 250th and align infinity with central marker the scale indicates 5 metres out of focus in the foreground . But when look through the view finder the foreground out of focus is much further than that . Perhaps as much as 30 metres or more . Which do I trust : the focus through the view finder or the lens scale ? There is a difference.

 

Put the infinity mark next to the f/number not the central marker, or as mentioned above use the f/number one down from what you are using. DOF works, one third in front and two thirds behind what you focus on. If you want maximum DOF with a small aperture look at the scene and focus on something one third of the distance into the scene which means you have one third foreground in focus and two thirds background as a rough guide. The more you stop down the wider this range becomes and more so with wider angle lenses. It is only a range of acceptable sharpness that DOF gives you however, the only thing that will be truly in focus is the thing you focused on.

There is jargon such as 'blur circle' and 'circle of confusion' along with plenty of other terms that more accurately describe how DOF works optically but unless you are interested simply understand what the end result does.

 

Edited November 3, 2024 by 250swb

[Helge]

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Am 1.11.2024 um 01:04 schrieb TomB_tx:

Sharpest focus is only at the distance at the center mark on the lane scale - the depth-of-field marks indicate "acceptable sharpness" over the range between the marks - but that "acceptable" is based on a medium-sized print at normal viewing distance. To get the most usable DOF from infinity at f16, set the infinity mark at the f16 line to the right of the lens scale. The left mark should show acceptable sharpness to a bit under 3 meters. You may do better to focus closer and let the infinity distance go a bit less focused.

Also, f16 will give a somewhat softer image even in the sharpest distance due to diffraction from the small aperture - but sometimes that's OK to get the DOF you want. Most lenses are sharpest at the plane of focus around f5.6 - but we take a lot of pictures at smaller apertures when the DOF is needed.

The „acceptable“ sharpness is no individual definition. For 24x36mm it is commonly defined as a „circle of confusion“ of 0.03mm. This common value gives you the 2 values for the depth of field by a calculation (dependent on aperture and focus length). This circle of confusion is good for far more than „medium sized“ prints, however with a higher resolution (film or sensor) you might tighten that range.

[jaapv]

If you really want deep DOF the only way to go is focus stacking - DOF is nothing more than the zone of acceptable UNsharpness. The only really sharp place in a photograph is the plane of focus

The COC of 0.03 is based on film ( and old thick types at that)  and A4 prints.  For modern film 0.02 is more appropriate and for digital use you should tighten it to 0.01. In the end it is influenced by subject matter (high frequency or low frequency), subject contrast and above all magnification - and obviously the tolerance of the photographer regarding unsharpness.

[Helge]

That is actually rather nonsense 😀

The COC is based on the format and there is always a transition from maximum sharpness at the distance set to maximum „unsharpness“ at the far ends (infinity and closest possible to the front lens).

The two points (beginning and end of DOF) describe commonly defined points of sharpness. This sharpness is defined by the COC and always the same whether you use film, „thin“ film 😀(whatever you mean by using the term „thick“) or digital.

As already mentioned by others, there is no real focus outside focus. The finer the medium is able to resolve the picture, the better you will see the transition…

Its just optics 

[Al Brown]

For reliable hyperfocal distance subtract 2 f-stops. If you have set your f-stop at f/16 you should set the hyperfocal distance on the lens to f/8 (2 stops less) and so on...