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  Previous versions of gromacs's message #16951087 « EF 400mm 2.8 IS II autofocus performance? »
  

gromacs
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EF 400mm 2.8 IS II autofocus performance?


Your numbers are off by many orders of magnitude.

Here's the actual math:

1.8m×400​mm/24mm=30m landscape
1.8m×400​mm/36mm=20m portrait

4.39 µm pixel pitch
CoC = 0.0088mm
400mm f2.8
At 30m, DOF is 29.88m to 30.12m
At 20m, DOF is 19.95m to 20.05m

Top speed is 0.85s per 10m
At 30m, the 0.12m is gone in 10ms
At 20m, the 0.05m is gone in 4ms


Dec 18, 2025 at 07:02 PM





  Previous versions of gromacs's message #16951087 « EF 400mm 2.8 IS II autofocus performance? »