The relative merits of these two lenses are always being debated -- the following is what the pros I know have to say about them (I'll include myself as well....). 1) 50-135 is way better at 50mm than the 75-150 2) 75-150 is way better than the 50-135 at all other focal lengths. In fact, it's center sharpness and contrast exceed those of the MF 105mm f2.8 Micro Nikkor although it has significantly more field curvature than the micro-nikkor. Also, all the versions of the 75-150mm Series E lens had Nikon's integral Multicoationg (NIC) applied to them. Mid range contrast resolution on this lens (75-150 Series E) is well in excess of 80 lp/mm (measured on a chart and on Opossum fur at 1/15 x lifesize). In fact grey-white hairs (not whiskers!!!) on a baby Opossum are easily resolvable at 1/15 lifesize even where they cross each other (on Fuji Sensia 100 and Velvia). Since an Opossum hair is ~75um in diameter this gives us a resolution of better than 100 lp/mm. By contrast on a similar scale the 50-135mm lens scores in with a "mere" 60 lp/mm or so.... Either is plenty sharp ehough for pro work, way sharper than desirable for portraiture. The 75-150mm is less expensive, but not as wide at the wide end. What do I always take with on a trip: 1) Long Cannon (600 f4 or 400 f3.5 EDIF) 2) 55mm f3.5 micro 3) 24mm f2.8 AIS 4) 28mm f2.8 Series E 5) 75-150mm Series E 6) 300mm f4 EDIF I'll carry either the 600,400 or on long hikes/climbs the 300 f4, one wide angle (either the 24 or the 28) and always the 75-150. Hope this helps out a bit..... Grover Larkins
