I have owned the H system since it first became available and at one time or another have owned all of the lenses (except some of the versionIIs). Comments above regarding diffraction are very pertinent. For reasons not clear based on the physics, the H lenses seem to be more sensitive to diffraction (deteriorate more rapidly per f stop) than other medium format lenses (although most of those I only used with film). I am so convinced of this that I avoid f-stops higher (smaller) than f11 with a passion. Also, elimination of vibration is essential, meaning heavy rigid tripod & mirror lock-up (move it to one of the programmable buttons on the rear of the grip for convenience). When this is done the sharpness can be spectacular. All of these issues became all the more critical when the H4D50 became my daily camera over the H3DII31 (reasons for this well documented in other LULU threads). I am suspicious that the diffraction effects may be more apparent on the medium format over the DSLRs because of the overall softening effects of the AA filter on the DSLRs which tends to hide/soften the transition. Also I must say that the 30 mm was never as sharp as some of the other lenses such as the 55-110 which has produced some "shockingly" sharp shots, especially at infinity. I finally sold the 30mm and switched to the 28mm which is perceptively sharper, even to non-photographers (but be careful of the edges on a more full frame sensor ... less of a problem with H*D31). One man's two cents. Bill
