The Olympus 40-150 f/2.8 PRO has been on my short list ever since it came out. I may pull the trigger soon. It would be used almost exclusively on my E-M1. I haven't had a chance to play with this glass... but in reading the specs, I see that it's bigger and heavier than Pentax's DA* 50-135 f/2.8 WR for APS-C, which is saying something indeed. So, my question for those who use this lens... what is the weight and handling like in the real world? Is this, in a practical sense, a tripod-only lens? I've got the 12-40 f/2.8 PRO and the Panasonic 100-300 f/4-5.6. If the longer Olympus lens is a problem in terms of handling in the field, perhaps I'd be better off with the new Oly 12-100 f/4.0 or the Panasonic 35-100 f/2.8.