SL2 DOF and Hyperfocal Information

[osroubek]

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I'm trying to better understand depth of field and hyperfocal distance information on the SL2. On the top display, when manually focusing with the button half-pressed it shows Back/Front/Focus information. If I obtain exact focus on the subject I understand what is displayed and the values make sense.  If I want to use hyperfocal focusing for example for landscape and try to retain foreground and background with acceptable sharpness  I read on this forum ( a recommendation from David Farkas) "To determine hyperfocal distance, just adjust the focus on the lens as far forward as you can, while still keeping the back reading at infinity." I tried this method but the readout for hyperfocal distance does not match what are the published hyperfocal distances for the lens I'm testing. For example, at F8 using a 75mm SL Summicron lens, the hyperfocal distance is supposed to be 77 feet. The camera indicates focus is at 180 feet while back focus is just at infinity, and front focus is 91 feet. This does not appear to be any where close to what one should be getting. Just wondering if anyone else has seen this or can explain it better for me. I would appreciate any information.

[convexferret]

8 hours ago, osroubek said:

I'm trying to better understand depth of field and hyperfocal distance information on the SL2. On the top display, when manually focusing with the button half-pressed it shows Back/Front/Focus information. If I obtain exact focus on the subject I understand what is displayed and the values make sense.  If I want to use hyperfocal focusing for example for landscape and try to retain foreground and background with acceptable sharpness  I read on this forum ( a recommendation from David Farkas) "To determine hyperfocal distance, just adjust the focus on the lens as far forward as you can, while still keeping the back reading at infinity." I tried this method but the readout for hyperfocal distance does not match what are the published hyperfocal distances for the lens I'm testing. For example, at F8 using a 75mm SL Summicron lens, the hyperfocal distance is supposed to be 77 feet. The camera indicates focus is at 180 feet while back focus is just at infinity, and front focus is 91 feet. This does not appear to be any where close to what one should be getting. Just wondering if anyone else has seen this or can explain it better for me. I would appreciate any information.

Hi. Where are you getting the published hyperfocal distances? The problem is that depth-of-field in general is a matter of opinion, there's no set standard and therefore any published information will reflect the preferences of the author. It's generally held that most older published tables are far too lax given the high resolution sensors and lenses that we're now using but it does depend on your output preferences as to what is acceptable.

[mike3996]

23 minutes ago, convexferret said:

The problem is that depth-of-field in general is a matter of opinion, there's no set standard and therefore any published information will reflect the preferences of the author.

Agreed.

23 minutes ago, convexferret said:

It's generally held that most older published tables are far too lax given the high resolution sensors

The tables aren't tied to pixel counts but rather the print size you want to print. If you upgrade from 24 megapixels to 47 but still print the same size as before, your old DOF tables remain valid.

[convexferret]

1 minute ago, mike3996 said:

Agreed.

The tables aren't tied to pixel counts but rather the print size you want to print. If you upgrade from 24 megapixels to 47 but still print the same size as before, your old DOF tables remain valid.

Of course, but people have the bad habit of checking their images not at the printing stage but rather at 100% in Lightroom or similar.

[mike3996]

9 minutes ago, convexferret said:

Of course, but people have the bad habit of checking their images not at the printing stage but rather at 100% in Lightroom or similar.

That people do! 😎

[jaapv]

35 minutes ago, mike3996 said:

Agreed.

The tables aren't tied to pixel counts but rather the print size you want to print. If you upgrade from 24 megapixels to 47 but still print the same size as before, your old DOF tables remain valid.

Not quite - due to the different ways of recording the images there is a difference between film and digital in OOF rendering. A sensor is more precise, for lack of a better description, resulting in the impression of a more shallow DOF, all other factors being the same.

[01af]

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vor 9 Stunden schrieb osroubek:

For example, at f/8 using a 75 mm Summicron-SL lens, the hyperfocal distance is supposed to be 77 feet.

That's right – for the 35-mm format's traditional circle-of-confusion diameter of 0.03 mm.

.

vor 9 Stunden schrieb osroubek:

The camera indicates focus is at 180 feet while back focus is just at infinity, and front focus is 91 feet.

This suggests the camera is calculating DOF for a circle-of-confusion diameter of 0.0125 mm (1/80 mm). Using a smaller COC diameter for a more stringent idea of 'acceptable sharpness' is ... umm, debatable.

[jaapv]

Happy to debate it, Olaf  

[Stuart Richardson]

I know that some people swear by hyperfocal focusing, as a printer I have come to standardize on thinking of focus as a plane, rather than a range. With high resolution cameras and lenses (whether film or digital), hyperfocal focus mostly works with small prints and web images. When you really dig into the details, the wider ends of the hyperfocal range are invariably softer than the center. In practice I find that the best image quality is obtained by finding the best composition to suit the subject and then placing the focal point on the part of the composition that is most important to be in sharp focus. I get that this is not always possible, and that sometimes you need to resort to hyperfocal focusing to get the photo you want, but I think it is better used to solve compositional challenges, rather than as a technique to be used in all cases. (This is a from a landscape standpoint...it makes more sense in things like street photography or night photography etc.

[FlashGordonPhotography]

i know I'm about to start up 25 pages of rubbish, so apologies in advance....

Many many things affect apparent DoF. Not limited to, aperture, print size, viewing distance, shooting distance. There are also things that mimic DoF and fool the eye: Subject isolation, lens compression, haze, heat and blur. Lens design. Even high ISO can fool us. How good your eyesight is also an influencing factor.

My advise is to ignore the charts and camera to a certain extent. DoF is about the acceptable unsharpness outside the plane of focus. Work out what is acceptable for you based on how you shoot and display your images and go from there. Foe example I know that to make me happy I need to add a stop to the recommended setting on a chart for how I perceive DoF.

YMMV. Shoot to your own standards.

Gordon

[Jared]

Hyperfocal distance, as mentioned previously, was based upon a circle of confusion size that was “reasonable” for 35mm film but still quite arbitrary.  Same for depth of field scales on lenses. As optics have improved and sensors have increased in resolution, the standard for what is “acceptably sharp” has changed.  In addition, things like print size can have a huge impact.  It appears that in creating the depth of field scale on the LCD of the SL2, Leica is using a less forgiving specification than the traditional 0.03mm circle of confusion that worked fairly well for film grain. That’s OK.  Any standard you pick is going to be somewhat arbitrary as soon as your circle of confusion is larger than your pixel pitch.

I would not bother to try and relate the SL2’s scale to the typical chart or to the typical lens markings. Instead, experiment to see if you find the SL2 values too stringent, just right, or too forgiving. Then adjust accordingly.  If you find it too stringent, measure closed down an extra half stop or full stop, then back off when you take the picture.  If you find it too lax, do the opposite.  Just right? Cool.  You would have to do the same for DOF charts or for lens markings.  Since I started shooting with 18+ megapixel cameras and making prints in the 13x19 or 16” range I have found the standards a bit lax and was routinely adjusting for the normal lens markings.  Luckily, with digital it is usually fairly easy to focus stack in most situations where hyperfocal distance is relevant, so conforming to a more stringent requirement is usually pretty easy. In fact, I often find myself opening up a bit to reduce the effects of diffraction and then adding a couple frames via stacking.  Depends whether you really want your whole image in a single frame or whether you are comfortable with software merging things.  Depends on the subject, too, of course.  Hyperfocal was never intended to be “true”, it was just “standard”. 

[masjah]

Even when I was using my R8/9 film cameras, I found the depth of field scale on my R lenses a bit too easy-going for (say) 10x15 inch prints. This was hardly surprising given that prints were smaller in the days when the criteria for acceptable unsharpness were first defined. I used to reckon to try to be at least one stop more stringent.

 

[osroubek]

Thanks to all of you for great dialog and advice!