Which Canon Lens for E-P1?
Hope the following SUBJECTIVE comments are helpful:
I own both, though I'm happier with the results I get from the 50-135mm when shooting on my Panny G1 w/ FD-MFT adapter. During my manual focus, film-shooting days, working for a newspaper back in the 80s, I had ample opportunity to use both, but always reached for the 50-135mm unless I knew for sure the assignment demanded the longer reach of the 70-210. I hung on to both these FDs after the demise of MF, Today I still consider the 50-135 the zoom of choice.
The shorter zoom had a snap and contrast that always translated wonderfully to b&w prints, though I never concerned myself with making comparisons about bokeh-- which I consider a tiresome fetish among many shooters these days--and I'm not about to start making bokeh comparisons now.
Even the slight softness I experienced shooting at f/3.5 imparted a lovely look to head & shoulder/torso portraiture. Any softness cleared up quite nicely by f/4.5 or 5.6, plus I preferred the handling characteristics of this smaller, more compact zoom design.
Whereas, I find the 70-210 to be somewhat mushy at full aperture, medium- to long- distance shooting. It was merely OK, but was outperformed by many other 70-210 and 80-200 zoom designs of its day.
Really, I think the 50-135 was one of Canon's most vastly underappreciated mid-80s lenses; perhaps too many shooters just figured it occupied a neither-here-nor-there focal length range. It enjoyed a relatively short production run and then Canon dumped a carload onto the market at bargain basement prices, while the Canon 70-210 and the 70-150 lenses of other manufacturers like Nikon remained on the market a while longer.
ANOTHER OPTION: Unlike the underrated Canon FD 50-135, Nikon's 70-150mm f/3.5 Series E zoom has always been a popular, well-regarded zoom, even among some professionals. If you're looking for something quite compact, with a bit more reach on the long end than the FD 50-135, but still want to stay with the Canon FD mount, try searching for either the Kiron 70-150mm f/4 or the Vivitar 70-150mm f3/8 in FD breech lock mount. It was Kiron that made the 70-150 Series E lens on an outsourced basis for Nikon, and consequently both the Kiron and Vivitar are very similar in design, operational feel and optical results to their Series E sibling.