[normhead]

Another thing, the Pentax 100mm WR has its front element so deeply recessed (which is common for macro lenses in the 90-100mm range) that a lens hood is not all that necessary, except for extreme conditions, so one can take full advantage of its compactness for pleasurable handling and convenience without concern.

The Tamron and 50 are the same, the Sigma is the only one where a lens hood is really critical. And the method Sigma employed with that lens hood is simply dark ages, but it too is recessed.

[BrianR]

Exactly our experience. The Tamron is better pixel peeping and staring for a long time but the other attributes of the 100, size, WR, weight etc. more than make up for that, at least for me..

Have you ever compared them for chromatic aberrations? At or near wide open, the dfa100 can get pretty colorful on high contrast edges. Really my only complaint with it (and a minor one considering the rest of its awesomeness).

The first Pentax DFA 100mm f/2.8 was very fine optically, having fine contrast, but not very well-built.

Its build is mostly lacking when compared with the WR model, but it's pretty durable overall I'd say.

Another thing, the Pentax 100mm WR has its front element so deeply recessed (which is common for macro lenses in the 90-100mm range) that a lens hood is not all that necessary, except for extreme conditions, so one can take full advantage of its compactness for pleasurable handling and convenience without concern.

It's a plus and a minus. Deeply recessed protects the front element but it also moves filters further away from it and you usually want them as close as possible for the best results. That said, the raynox DCR-250 is a nice combo with this lens, but I wonder how much of a difference it would make if it was closer to the front element (no, I don't wonder enough to take a hacksaw to mine).