09-28-2011, 09:54 PM
[quote name='RussellB' timestamp='1317009344' post='11856']
Great posts, Wim, thanks much. So nice to have the super simplified diffraction limit formulas of 1600 over aperture for lens aerial resolution with 9% MTF...and the roughly "3.2 times pixel pitch in micrometers" formula for smallest aperture that can still deliver resolution approaching what the sensor can resolve. What's the 50% aerial MTF version of the 1600/aperture formula? Obviously the number 1600 would be smaller.
[/quote]
Just got home and looked it up for you.
For MTF-50 the number to use is 760 lp/mm for the 0.0005 mm wavelength, and 740 lp/mm for 0.000512 mm.
As a simplified formula, f50 = 0.38/(Nω), which equals approximately 0.46*Rayleigh limit. ω is the wavelength here, and N the f-stop setting. Set the latter to 1, and you get the number you are after. Wavelength to be expressed in mm, BTW.
Kind regards, Wim
Great posts, Wim, thanks much. So nice to have the super simplified diffraction limit formulas of 1600 over aperture for lens aerial resolution with 9% MTF...and the roughly "3.2 times pixel pitch in micrometers" formula for smallest aperture that can still deliver resolution approaching what the sensor can resolve. What's the 50% aerial MTF version of the 1600/aperture formula? Obviously the number 1600 would be smaller.
[/quote]
Just got home and looked it up for you.
For MTF-50 the number to use is 760 lp/mm for the 0.0005 mm wavelength, and 740 lp/mm for 0.000512 mm.
As a simplified formula, f50 = 0.38/(Nω), which equals approximately 0.46*Rayleigh limit. ω is the wavelength here, and N the f-stop setting. Set the latter to 1, and you get the number you are after. Wavelength to be expressed in mm, BTW.
Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....