I have the ATN 4K 5-20x with the latest firmware 3.1.03.271 and have decided to return it.
My main complaints is for what this thing cost (and I ordered the rangefinder that attaches to it as well but haven't received it yet), I expected better.
I found the digital zoom just too grainy for my taste. Glass quality is meh. At 20-35 yards its fine but at 50 it's unacceptable.
here the picture at 50 yards with a 20 shot group if I recall (2 mags from my .22 Vulcan Tactical shooting JSB 18gr diabolos.
I am using the highest magnification with the extended setting in the advanced menu, about 50x.
(ignore the time stamp, it resetted while I was trying to edit my profile in the menu and I didn't notice. This was yesterday.)
I also had the screen freeze on me several time that required a long press (10+ sec on the power button) to shut down. Firmware while improving is still buggy.
I did really like the zero reticle feature, really easy to use. I love the HUD knowing wind, inclination, compass heading, pressure, temperature, built in level...
I mean this thing is a technology treasure trove. I debated keeping just as a spotting scope... the photo and video recording is also very convenient.
The night vision is also pretty decent. The included 3 scope rings are a very nice touch but the included ir light while bright enough for 30 yards should have included a rechargeable battery.
In short, if your shooting under 35 yards and need nightvision, this is great but past that ymmv.