[Closed] STUPID photo

is it not in fact entirely independent of the lens and only dependant on the relative aperture ?

That's what I thought, but I've been told that it also depends on your focal length to some degree. I've not put that much thought into the physics of it TBH, but intuitively I'd agree with you. Of course you're right with relative aperture, as it depends on the camera sensors pixel density AND the aperture rather than just aperture.