Didn't like my Viper 10x50s.
The diopter was far too easy to inadvertently move (no locking mechanism) because my natural hold put my thumb right up against it and the focus was way too fast - very easy to go past point of beat focus and have to go back and forth to find it.
On a 3 day hunt, mine was constantly collapsing one or the other eye cup, making a quick look impossible.
The glass was very nice, though.
