I previously used Vortex Diamondback 8x42 binoculars for whitetail hunting in the Northeast. After moving to Alaska it quickly became obvious I was going to need to step up my optical game. In my opinion 8 power binoculars are not enough for western mountain hunting and because I also use a spotting scope, 15 power is too much zoom for my binoculars. Because I am in a position to only buy one pair of binoculars and wanted the most versatile pair possible, I had to figure out whether that pair would be 10 or 12 power and a 42 or 50mm objective. To answer that question I made the rounds going to Cabelas, Sportsman's and a specialty birdwatching store. I personally looked through and handled Swarovski, Leica, Zeiss, Vortex, Leupold and GPO. When comparing each of these companies flagship binoculars it can be hard to notice all of the differences in optical quality. As expected though, the image of the Swarovski NL Pure and Zeiss Victory SF were best followed by the Leica Noctivid, Vortex Razor UHD and GPO Passion HD. Personally what I have found to be more important than minor differences in image quality is the ergonomics and overall quality of construction of the binocular. In this category I would still give the edge to Swarovski and Zeiss but right up there with Zeiss I would put the GPO Passion. In fact the GPO felt and looked very similar to the Zeiss Victory. (Quick side note, the Zeiss Victory is great but the Zeiss Conquest is embarrassingly bad for the price). This is no surprise considering GPO was founded by a former Zeiss executive. The GPO Passion really impressed with the silky smooth focus, locking diopter and perfect resistance in the twist of the eyecups. In my opinion the Swaro's were the best overall followed closely by Zeiss, Leica and GPO; however, considering the GPO Passion was about $2,000 less than the three Alpha glass companies, it was an easy decision for me. In regards to the zoom I decided that ten power was the best compromise between zoom and field of view plus they were a little easier to hand hold than 12 power. I personally decided to go with the larger 50mm objective because the added weight was worth the better low light performance and size of the exit pupil. I did have to buy a larger bino harness from Stone Glacier to be able to fit them but overall I am very pleased with these binoculars.
In conclusion, the overall quality of the GPO Passion's are on par with the very best binoculars for thousands of dollars less.