Hyperfocal Distance

[Jim Jones]

Jim, I just checked my DoF calculator (mine = I wrote it). It strongly disagrees with you. You can download it from http://1drv.ms/1Ai54SN . Please show me yours. . . .

Oops, when I said the hyperfocal distance was about 2000 times the entrance pupil, I neglected the critical element of the image being viewed in correct perspective. Corrections for deviations of viewing perspective can be done mentally in the field with basic math. Your spreadsheet applies to the special condition of constant magnification. I change lenses more to change the field of view than to change the subject distance for constant magnification. As for the math used to derive the formula I use, it was done decades ago with pencil and probably a slide rule, although by then I might have had a new and amazing five function digital Heathkit calculator that cost only $128, and had to be wired and assembled from the individual components. The math was merely a step in understanding practical optics. Once there, the math could be forgotten, and was. Kingslake in Lenses in Photography gives the formula for hyperfocal distance as 1000 d = h where d is the entrance pupil and h is the hyperfocal distance. This seems too lax for modern film and printing, and too forgiving for Facebook selfies.

[Dan Fromm]

Jim, look at the second tab.

[Jim Jones]

Jim, look at the second tab.

For someone who was a computer maintainer from 1956 to 1959, I hate to admit being almost totally ignorant of spreadsheets and most other modern programs. A quick study of spreadsheets this morning wasn't enlightening to an aging mind. It's back to the copy of Kingslake sadly tattered from 60 years of use.

[Dan Fromm]

Jim, I too have seen ferrite cores. But hardware has little to do with software.

You really should learn to use modern tools, they're useful. And I say this even though my best unpublished paper in comp sci's title is "Spreadsheet Languages Considered Harmful." For context, see http://xkcd.com/292/

[Emmanuel BIGLER]

I hate to admit being almost totally ignorant of spreadsheets and most other modern programs.

Same for me. However some day I had to deliver our student's results after their exams under the form of a spreadsheet file.
Since this day I've discovered how to tweak with students' marks in terms of expected average, standard deviation, and number of students who eventually fail ;-)

And as far as DOF calculations are concerned, having learnt FORTRAN with punched cards, even a spreadsheet in the style onf the 1990's is too modern for me, I prefer an analogue do-it-yourself slide rule of this kind.

[Drew Wiley]

As a formally trained commercial photographer, my brother was addicted to those hyperfocal scales on typical MF lenses. I ignore the entire subject and simply
evaluate the problem with my eyes using the GG loupe. What features in the scene do I want in exact focus, what will print acceptably stopped down (just
do it and look at the effect thru the loupe!), and what might I want deliberately out of focus. This is esp easy on the big GG of the 8x10. But I pretty much know
what to expect just from experience with given lenses anyway. Maybe once on the last trip when I didn't have enough time to set up the view camera due to rapidly changing light, I did use the hyperfocal formula for a particular 6x7 shot, and in the print it was obviously a successful strategy.

[Jim Jones]

Dan, JK flip flops, not ferrite cores, were used in that computer in the 1950s. It was built with Univac I technology, although bigger and slower. It had hardwired components and lots of vacuum tubes. I wasn't familiar with ferrite cores until 10 years later.

Drew, a fine ground glass screen and strong loupe is certainly the best way to check DOF and focus. It would have been awfully inconvenient, although not quite impossible, when using Leica rangefinder cameras for many years. Most SLR viewfinders don't have enough magnification. DOF scales were often good enough, but not for occasional demanding photography. I wrestled with those optical formulas to find out why some photos displayed insufficient DOF.