I've tried a few similar binoculars. I had a Celestron 8x30 model a while ago, that was sent back as it had excess play in the focus mechanism. At the moment I have an Olivon 7x30 porro that looks identical to the Nature trek.
My problem with the examples I've had of waterproof porro in this style is the focus. It appears to me that because there is some kind of greased seal on each eye-piece, each can have slightly differing resistance to movement up and down the body. This causes one or other of the eyepieces to lag a little. Adjusting the dioptre to suit isn't possible as it's different nearly each time, and of course worse in the cold.
I tried a couple of new strategies to help get over this. One was to push the eyepieces gently into my face to provide a sort of spring loading to get them to move in predictable ways, the other was to hold them off the body by light finger pressure. These are not solutions that I can recommend and only brought partialy better focussing. The other, lesser problem has been that the central focussing ring had axial play. Before the bridge is moved the ring has to worm its way to the stop. Small amounts are tolerable, but too much is, er, too much.
All this is a real pity, because "once it's focussed", it gives a nice detailed view.
I hope that with use, the focus might wear in a little. In the meantime, I now regret not spending more and getting the Vortex Raptor or the similar Kowa porro 8x. I had a Raptor for a few hours before returning it as it had a big ding on the objective surrounding. I recall that the focus worked properly on it.
Perhaps these were just problems with poor examples that came my way. It's put me off buying similar bins untried.
Dave
