I once tied myself in knots evaluating the Zeiss 25mm (using an adaptor) versus the Canon 24mm T&S and the Canon 24-105mm at the 24mm setting. This was with a full frame 1Ds MkII. At anything less than infinity and at f5.6 the 24-105 seemed to be very, very slightly sharper than the other two, but with fractionally greater distortion and vignetting. At f8.0 or smaller, or at infinity, I couldn't see any meaningful difference between them.
It was at about this time that I vowed (sadly for the 100th time) that I'd stop chasing illusory quality gains and concentrate instead on trying to take better real-world photographs, which in practise usually means waking up earlier, seeking permission to photograph from private property, travelling further, experimenting more with studio lighting, looking harder at the scene in front of me, returning to a location multiple times in different light, being pushier in street scenes, etc. In fact almost anything apart from fretting about lenses which looking back over forty years of photography has actually yielded very few dividends!
