It's really all based on a presumed visual resolution of an 8x10 print
at a reading distance of about 10". But it holds pretty well beyond at
larger prints and lower resolutions since we view such prints from
farther away. Works for me. If you don't like it change to 80 lines/mm
or whatever works for your eyes. The major confusion point, of course,
is that the image does not suddenly fall apart at 307 or 309mm.
Chuck Norcutt
On 5/11/2016 4:26 PM, Moose wrote:
BTW, my DoF calculator set at a modest CoC for 4/3 (.0167 or 60
lines/mm) says the 12-50 in macro mode (fixed 43mm) and focused at
300mm (a bit shy of 1 foot) has DoF range (rounded to the nearest mm)
@ f/8 - 295-306 mm
@ f/11 - 293-308 mm
I can never figure out what this stuff means. It's all predicated on
display resolution, display size, viewing distance and an assumption,
perhaps unstated, about visual acuity. If I view it large on a big
screen, I will perceive a different DoF than someone with less visual
acuity, a smaller screen, and/or less resolution.
--
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