Example Q calculations for Bayer CFAs

Restating the Q formula from this post with the Bayer CFA correction from yesterday’s post:

Qbayer = lambda * N / (pitch *1.7)

Where lambda is the wavelength of the light in micrometers, N is the f-stop, and pitch is the pixel pitch in micrometers.

For 0.5 micrometer light,

Qbayer = N / (pitch *3.4)

Since a Q of 2 means that the sensor and the lens are “balanced”, we can relate f-stop and pixel pitch for balanced systems:

N = 6.8 * pitch

or

pitch = N / 6.8

For a setting of f/6.8, we want a 1 micrometer pixel pitch. For a setting of f/8, the pixel pitch should be 1.18 micrometers. These numbers are much finer than any available sensors sized at micro 4/3 and larger.

If we think the correction factor should be one,

Q = lamda * N / pitch = N / (pitch * 2)

And for a “balanced” system

N = 4 * pitch

Or

Pitch = N /4

At f/8 we want a 2-micrometer pixel pitch, still finer than currently available for any available sensors sized at micro 4/3 and larger.

The bottom line is that any interpretation of applying image system Q and the idea of the balanced system to Bayer arrays gives the result that, for fine lenses, resolutions of at least a binary order of magnitude higher than currently available are desirable. This argues for 200+ megapixel full frame sensors.

This is at variance with conventional wisdom.