This is not to say it's not a great lens, IQ and other-wise, but the big argument against it (and mine) is that it is too large and heavy. I have considered it many times in the past and everytime have decided against it. It just doesn't seem worth it to me to lug that thing around for the extra reach over a PL 12-60:
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Note the 75-300 on the other side - it's almost the same size and the 75-300 weighs 423g vs 561g for the 12-100. Yes, I know that one is a constant f4 and the other is a variable slow lens. But again, it's just more than I would ever want to carry. I have a Canon 15-85 lens in DSLR APS-C lens (12-136mm equivalent). That's about the same weight as the 12-100, but not as long. That's larger than I want to carry too, but at least it has more reach. I do want to like that 12-100,
but I'm not the only one who thinks it's too large; it's a common complaint.