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M240 depth of field


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Hi - I just purchased my first Leica camera - an M 240 (second hand) as well as an Elmar 24mm lens. If I try and maximise the depth of field at f11 say by focussing the infinity mark at the f11 depth of field marking on the lens, or by focussing at the hyperfocal distance, the foreground is crystal clear, but the background is slightly blurry.

 

In order to get a clear background, I have to focus the lens at a much long distance than the hyperfocal distance.

 

Could there be an issue with the equipment, or have I missed something fundamental?

 

Thanks.

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Focus by the rangefinder on the subject. Experience will teach you which aperture to use to get the DOF you are looking for.

If you want the horizon to be sharp - focus on the horizon. i.e. infinity. DOF is the zone of acceptable UNsharpness.

 

This has nothing to do with Leica, but with basic photographic principles.

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Welcome to the forum, @pkorotography. In a world where automatic focus is considered 'normal' it is not surprising to hear of your confusion.

 

Go back to basics. Set your camera to 'A' for light measuring and that will remove half of your problems.

 

Then, as jaapv suggests, use the focussing ring to choose your focal point. This is different from most cameras today. You get to choose rather than the computer inside the machine.

 

In my experience before all this automation the most difficult thing was getting the exposure correct. I never minded automation of that difficult task.

Focussing is simple in comparison. 

 

Depth of field depends on the subject and whether you want a blurred (out of focus) background in order to create a 3D image.

 

Your eyes, when it is a bright day, close the iris of each eye and create a huge depth of field (scope). On a dull day or in twilight the opposite happens. The iris of each eye opens and what you see is just what you are looking at (focus). Everything else is blurred. That is known as 'Bokeh' and provides the 3D type image.

 

You can adjust your camera to the available light using the ISO function. In very strong light, such as the south of France in summer, you will need very low ISO (International Standards Organisation) settings. In a coal cellar, trying to snap a black cat, you will need the highest ISO setting.

 

I hope that simple explanation is helpful.

 

P.S. Before some clever clogs wants to come on here and say that setting the exposure for light is simple then please keep quiet. For basics it is not necessary to confuse the issue however easy you find it. I do know how to do it after years of experience but it certainly isn't simple.

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Depends at what magnification you view your pics as DoF depends on magnification as you know. At 25% magnification on screen your settings should be okay i guess but at 50% or 100% DoF is shallower of course so instead of f/11 you may wish to choose f/8 or f/5.6 to focus the infinity mark on. 

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Hi - thanks for all the replies. I've tried measuring the hyperfocal distance by focusing at infinity and looking at the resulting image to find where it starts to lose focus, which is by definition the hyperfocal distance. This appears to be around 3.5m measured to the best of my ability. The lens markings and nearly all DOF calculators I've used put the hyperfocal distance at around 1.8m, which is the bit I'm confused about.

 

I've given up and have changed my routine to take one photo focused at infinity and one more focused at a closed range. The resulting images are then focus stacked. This seems to work just fine.

 

Cheer,s

Edited by pkorotography
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Always remember that DoF - as lct says - depends on final image size. And - DoF is not what is sharp, but what looks sharp at that final image size. Appearance vs. reality. Relative sharpness vs. absolute sharpness.

 

And for the most part, that is assumed to be a 5x7" or 8x10" print. Call it an 8X enlargement. 

 

If you look at pictures at 100% pixels, you are effectively asking for DoF that still looks sharp at a 30x45" enlargement. And neither the engraved DoF scales nor the traditional calculation of "hyperfocal distance" still work at that scale. You either need to focus on the one thing you really want sharp (as jaap says - because there is no longer any leeway at 30x) - or as lct says, view your pictures at the size for which the DoF/hyperfocal distance is intended - about 8" x 12", whether on your computer screen, or in a print.

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Well, issue of DoF applicability is in the area of CoC (Circle of Confusion). Lens engraving and many tables are based on wrong assumption of CoC, based on small enlargement scale. Picture of modern camera might be enlarged at higher scale.

CoC is connected with size of grain (or cell size). I can suggest you to use as CoC parameter 1.5 size of cell - 0.009 or simply 0.01 mm. Try and test it with appropriate DoF calculator. (For Mm and M246 - this is cell size)

 

 

However - Leica M-Lenses are exclusive. Something is made in design with transition from sharp zone to nice bokeh. Thus, I suggest to change a habit: close lense for two stops from opened diafragm and focus on the main element of the scene. Thus - main item will be sharp, all the rest at bokeh, and you’ll get the picture you’ve paid for. It is simply incorrect to use a habit “f/8 and been there” with this system.

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1. Average magnification was  in fact a maximum magnification at a time around WWII.  Somehow CoC size was proportional to the grain size of  135 film at the time. 

 

2. Connection of CoC to cell size is solid foundation for calculations. It is not possible to enlarge picture after certain size without loss of visual quality. It is about 240..250 non-interpolated Pixels per inch of print. 

 

3. Bayer sensor has a loss of visual details due to demozaic calculations.  Monochrome sensor is free of such calculation (if raw programmer was honest enough).  I assume, that min CoC for  Bayer sensor is about 1.5 cell size,  and 1 cell size for monochrome (or sigma foveon) sensors. 

 

Basing on this reasons I assumed correct CoC value.  It was in the past in the pre-leica (nikon and fuji) time of my photography hobby.  That I realised that I have to use tilt and shift lenses.  After a while I've switched to Leica.  Today I prefer blurred background at the infinity distant with meaningful foreground.

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Depends at what magnification you view your pics as DoF depends on magnification as you know. At 25% magnification on screen your settings should be okay i guess but at 50% or 100% DoF is shallower of course so instead of f/11 you may wish to choose f/8 or f/5.6 to focus the infinity mark on. 

Bingo! The DOF scales on Leica's lenses harken back to the days of film.  In the new paradigm of pixel-peeping, those scales are optimistic by 1-2 stops. 

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Bingo! The DOF scales on Leica's lenses harken back to the days of film.  In the new paradigm of pixel-peeping, those scales are optimistic by 1-2 stops. 

 

DoF scales are not made for pixel peeping as you say but not everybody is a pixel peeper and i don't see significant difference between film and digital at average magnification. YMMV.

Edited by lct
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Bingo! The DOF scales on Leica's lenses harken back to the days of film.  In the new paradigm of pixel-peeping, those scales are optimistic by 1-2 stops. 

 

Yes! And since DOF scales can't be changed (old lenses can't be re-engraved) and changing those on new lenses would lead to lots of confusion (I can imagine the vast number of forum posts already: is my lens pre- or post- DOF changeover :o), Leica still continue to use scales intended for film photography. This makes sense if you think about it ;).

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