[CGW]

I agree 100 percent with that (right down to not using mine much). It is kind of funny that Nikon nailed it so well with two successive and completely different versions of that lens. I do have a guess that this fl/aperture might happen be a relatively easy target to hit. I always thought that Nikon's "E" series 100mm was an extremely nice lens also, and I had an Olympus 100/2.8 (IIRC) that was my favorite lens of the ones I had in that system (when the OM system was new). (Just edited to mention that I realize these last two examples do not in any way live up to the build quality and durability s-a mentioned for the 105's)

When you bump up a stop, the field of lenses start to drift into different directions more noticeably.

The large number of RF105/2.5s sold obviously proved that the market loved 'em enough to carry the original design and its kids forward with successive SLRs. I prefer the 100/2.8E for its size and weight. It really gives away very little to the 105/2.5. The 105/4 Micro is also sweet but a bit hard to find. I'm still a sucker for the old 85/1.8 and prefer it to the later--and very different design--85/1.8AF. The 85/2 didn't really cut it. Ironically, the new and dirt cheap(<$300) manual Rokinon 85/1.4 is looking like a killer lens on film and digital cameras.