Not a big fan of zooms. When I do have one I usually fear the worst, to the point of more often than not thinking myself out of them in reasonably short order.
The 75-300 is a different story. It has never owed me much (even after my second one), but has delivered well out of proportion to it’s cost.
The 12-100 has a lot more work to do to convince me. It cost a bomb compared to my current kit (I have had dearer, but not by much and not anymore), it is out of my comfort zone weight and size wise and it is my enemy of enemies, a superzoom.
The 100 f4 seems to be about on par with the 75-300. Is that a compliment to the cheap lens or a disappointing result from the pro lens? I tested the 12-100 against a bunch of good to great lenses at 12-45mm focal lengths and it did well against the pack, beating most, but I did not test it at the long end.
I will do some more scientific testing soon, mainly out of curiosity, not necessarily fear of a dud. I know it will do the job it was bought for (landscape), I just need to get back to using my primes more for general stuff and stop using this lens out of laziness. It was specifically bought for another purpose.
I purchased this lens as a work horse do-it-all landscape and semi macro lens, with added AF benefits if needed for paid work. That is what it is good at and that is what I have to remember when choosing my gear. It takes months, often years before I can fully settle down with a lens and my expectations seem to be ever higher*. Early jitters have to be worked through. The reward is a reliable friend with a known personality.
*It seems I have already moved on from the relatively fine 16mp files of the EM5’s. How quickly we forget.
See the technical section for a more recent field test of the 12-100 f4 on the Pen F.