Of course, to be fair to BJL, he has already conceded that telephoto lens design cannot provide the extra quality necessary to compensate for the smaller sensor, so comparing a Zuiko 150mm lens with a Canon 300mm merely confirms this fact.
If we examine the other end of the range, the situation is quite different, but I'm not sure if the reason is that Canon simply do not make high quality wide-angle lenses.
The Zuiko 7-14mm F4 seems to be so good I feel like buying an E-500 just so I can use this lens. The nearest Canon equivalent is the 16-35/2.8. The Zuiko has the advantage of being slightly wider. The Canon has the advantages of being one stop faster, lighter (surprisingly) and cheaper.
The MTF charts for these two lenses are here
The thin solid and dashed lines on the Canon charts represent contrast at 30 lp/mm. The orange lines on the Zuiko chart represent contrast at 60 lp/mm. If the Zuiko MTF response at 60 lp/mm is as high as the Canon MTF response at 30 lp/mm, we could claim that the Zuiko lens has double the resolution, which it needs to have if the 4/3rds system is ever to equal the image quality of FF 35mm.
Examining these charts at equivalent distances along the x-axis, ie. comparing response at 2.5mm from the centre for the Zuiko with 5mm from the centre for the Canon and so on, it seems to me that the Zuiko has more
than double the resolution of the 16-35, ie. on the whole its response at 60 lp/mm is actually better than that of the Canon at 30 lp/mm.
Dear me, Canon. You really will have to lift your game otherwise Olympus will steal the show .
I wonder if there's any way I could fit this lens to my 20D? The MTF response is so flat, the fall-off at the edges of the slightly larger 20D sensor might not be noticeable.