Mamiya 7 and the foggy art of hyperfocal focusing

[one90guy]

I read all the posts yesterday and reread them again today. This all seems to me like taking something, focus, and making it so much more difficult. Now have never taken a magnifying glass to any of my photos and the ones that are enlarged almost always look fine. I have sold a few, given lots away, and shot a car show for pay with zero complains and also sold some prints. My F4 tells me when its focused and the Canon P lens gives good focus.

This is just my take on the subject, no trying to disagree with anyone. Am sure there are folks that have way more experience in this subject.

zilchOmd thank you for your explanation of hyperfocal focusing. and you made me want to revisit the subject. Its been years since looking into it and at the time it gave me a headache But since retiring there is more time to dedicate to photography.

David

 

[Alan Klein]

When I shoot landscapes with my RB67, I calculate the DOF I need. Then I stop down one extra stop for good measure. Since I also bracket, I'll use the shutter for that and always keep the aperture at the same setting.

 

[wiltw]

When I shoot landscapes with my RB67, I calculate the DOF I need. Then I stop down one extra stop for good measure. Since I also bracket, I'll use the shutter for that and always keep the aperture at the same setting.

In view of the fact that the fundamental problem of most DOF calculators -- and the DOF scales on most lenses -- is that they assume human vision is poorer than what your optometrist tries to acheve when calculating your prescription diopter strength for each eye, the above is a good practice to correct SOMEWHAT for that visual acuity fallacy. But it still does not end up reflective of 20/20 visual acuity, nonetheless.

 

[zilch0md]

zilchOmd thank you for your explanation of hyperfocal focusing. and you made me want to revisit the subject. Its been years since looking into it and at the time it gave me a headache But since retiring there is more time to dedicate to photography.

David

You're welcome, David!

The formula for determining the CoC that should be used for DoF calculations reveals only two variables affecting how small that circle of confusion must be at the film plane: enlargement factor and your personal preference for final print resolution (which, should take into account the anticipated viewing distance).

And yet, within this thread and throughout most forums where aperture selection and focus distance are debated, in regards to the spread functions of defocus and diffraction, you only rarely see any mention of diffraction, and the people who sometimes "come to blows," never attempt to quantify their personal preference for final print resolution.

Ironically, this information is as old as the hills, yet is all but forgotten. The concept of a "standard viewing distance of 25cm" is lost, especially. It was never meant to dictate that all prints should or will always be viewed at a distance of 25cm (9.84 inches) but was, instead, meant to allow discourse and comparison of resolutions expressed in terms of line pairs per millimeter. If one guy says, "I strive to support a resolution (actual subject detail) of 4 lp/mm in my prints, there was a day, when it went without saying, that this meant: "I desire 4 lp/mm in my final print at a viewing distance of 10 inches, which is the same as securing 2 lp/mm in a print to be viewed at 20 inches or 1 lp/mm in a print to be viewed at 40 inches."

Thus, the "standard viewing distance" of 25cm permits discussion and comparison of print resolutions, without having to refer to angular resolutions - which are not dependent on viewing distance. 6.88 lp/mm at the standard viewing distance is equivalent to 1.0 arc-minute of angular resolution - the figure used by THX, as the limit of human visual acuity, for theater design considerations, but it is generally accepted that healthy human eyes can resolve, on average, about 8 lp/mm at the standard viewing distance (25cm), which equates to 0.86 arc-minutes, expressed in angular resolution.

There's no way around it, sooner or later, any photographer who is truly interested in squeezing out every last bit of resolution from his system, will have to start by deciding what final image resolution he personally desires. There's no right or wrong, but you must get a figure in your head and then work backwards, to achieve that goal. Any other approach will yield some sort of compromise, as when stopping down further than you had to, in the quest for DoF, only to a greater risk of diffraction impacting your resolution goal across the entire print and longer exposures, which can make the system more vulnerable to subject and camera motion, etc.

Mike