I bought the 3-15x42 at Cabelas last month when it was on sale for $399. Put it on top of my Rem 700 VSF and brought it to the range. Everything is excellent out to 8x magnification, then it starts to lose its clarity / focus. At 15x I couldn't make out the target clearly at 100 yards.
I brought it home and took it off the rifle and tried a similar test holding the scope... same thing, looking at my neighbour’s fence 50 yards away it lost focus at 8x and got worse as I dialled it up.
I returned the Scope to Cabelas and it's in the process of getting refunded as we speak.
I read a lot of reviews prior to buying and they were mixed, some really good, some not so much but I thought I'd take a chance...
Anyways, I replaced it with a Vortex Viper 6.5-20x44 and it is awesome. IMHO it is far better than the Minox ZA5.
Jeff