09-23-2020, 10:39 AM

An extract from Using an HP48G Series Calculator to Determine Focus Distance, f-Number, Diffraction Limit f-Number, Shutter Speed and Base (for Stereography), Michael K. Davis, FEB 2017, 16 pgs.

" … load the equations, listed below … the beautiful thing about HP’s programmable calculators: Once you’ve stored an equation, you can solve for any variable, at will. You don’t have to store multiple arrangements of the same equation. Having just performed a calculation to solve for the f-Number that would provide sufficient DoF for your specified Near and Far distances, Focal Length, and Maximum Permissible CoC Diameter, you can, for example, easily overwrite the calculated f-Number with a different value of your choosing, then solve for any one of the other variables – solving for a new Near distance, for example, if you wanted to stop down or open up from the originally calculated f-Number and adjust your camera position, accordingly. This flexibility provides a spectacular advantage over having to program and select from multiple derivations of the same equation.

It is even more advantageous, in my opinion, when working with a Stereo Base equation. I can use it to solve for how far apart my two lenses should be (Base) for a given combination of FL, Viewer FL, Near and Far distances and my desired on-film-deviation (expressed as a percentage of Maximum Acceptable OFD), just as easily as I can solve for how close the Near can be for a change in Base, or what deviation (%MAOFD) will be recorded for a different Near with the same Base … "

BEST!

SlideRule

" … load the equations, listed below … the beautiful thing about HP’s programmable calculators: Once you’ve stored an equation, you can solve for any variable, at will. You don’t have to store multiple arrangements of the same equation. Having just performed a calculation to solve for the f-Number that would provide sufficient DoF for your specified Near and Far distances, Focal Length, and Maximum Permissible CoC Diameter, you can, for example, easily overwrite the calculated f-Number with a different value of your choosing, then solve for any one of the other variables – solving for a new Near distance, for example, if you wanted to stop down or open up from the originally calculated f-Number and adjust your camera position, accordingly. This flexibility provides a spectacular advantage over having to program and select from multiple derivations of the same equation.

It is even more advantageous, in my opinion, when working with a Stereo Base equation. I can use it to solve for how far apart my two lenses should be (Base) for a given combination of FL, Viewer FL, Near and Far distances and my desired on-film-deviation (expressed as a percentage of Maximum Acceptable OFD), just as easily as I can solve for how close the Near can be for a change in Base, or what deviation (%MAOFD) will be recorded for a different Near with the same Base … "

BEST!

SlideRule