I recently completed the Inca Trail, trekking 4 days thru the Andes to Machhu Pichhu. I took along the EM1 with 12-40 pro. I carried this combination on a Peak Design Capture clipped on my Backpack strap. The camera was uncovered and exposed to the elements. We went thru ecosystems ranging from rain forest to an altitude of 4200mts crossing the Dead Womans Pass. We encountered the blazing sun as well as driving rain. The camera/lens combo handled the elements reasonably well. There were 2 issues: Occasionally I needed to remove the battery to reset the camera for no good reason. More annoyingly, the post element in the lens would fog up at times requiring disconnecting the lens from the body. Overall very happy with the performance of this "Pro" combination. Any hints on avoiding the fogging would be helpful.