i was on a hunting trip several years back and had a bushnell scope.i was cold and rainy.the scope fogged up and got wet on the inside.the moisture was not from the rain.i had a simmons that got darker and darker.company said it had a crack on the inside.i bought my first leupold,when i got to where we were hunting i thought i needed to shoot it again to make sure it was still on.it was off.the left to right crosshair locked up and would not move.it does happen in the field and when getting a scope you get what you pay for.