DaveFP wrote: realVivek wrote:
Should be the other way around?
Petegh wrote: DaveFP wrote:
Anyone know offhand where diffraction starts on the A7R4 ?
It starts at f4 for the blue spectrum, f5.6 for the green, and all three by f8.
ROY G BIV
Red Orange Yellow Green Blue Indigo Violet
would suggest that but I don't know for sure....
Diffraction becomes important when the wavelength of the wave is (at least) on the order of the size of the aperture, so for some fixed aperture it happens to larger wavelengths first, i.e. the blue end of the spectrum.
You can understand this intuitively by the following: we all know large apertures don't make us worry about diffraction, right? But decreasing the aperture is equivalent to increasing the wavelength, since these are the only two physical scales we are considering. So large wavelengths are affected more, just as small apertures are.
