Years ago I owned and loved my Zeiss 7x45 Night Owls, but it was very difficult to justify their size and weight as optically nearly-equal, but much lighter alternatives were introduced - so I sold them. I have wondered ever since, why every pair of Zeiss Victory and Victory FL binocular has left me so unmoved (either optically or mechanically). Was it possible that the Night Owls had some magical image/build quality that Zeiss has simply been unable to recapture (as with the 7x42B/GAT)? Well, I just came across a beautifully maintained Zeiss 10x56 Night Owl, and using them has been quite a revelation. First, they are big and heavy - more so than the newer 10x56 FL's. But the image quality - WOW!!! They are sharp (especially in the center - a Zeiss signature) and bright beyond compare (Abbe-Konig prisms). The image sparkles in the same way that the 7x42 B/GAT image sparkled (and the 7x42 FL). Now, the weight is understandably a deal breaker unless, like me, you have a masochistic streak when it comes to superior optics. But, the primary reason for their heft is that this is the last pair of binoculars Zeiss made using "environmentally unfriendly" leaded Schott glasss. This glass was developed and perfected over a 100 year period, and perhaps this explains something. By moving away from leaded glass (and very thick elements at that), Zeiss had to re-invent similar (or superior) performing optical glass - which they clearly have with the FL. Everything that came between the Night Owl and the FL though, had unacceptable levels of chromatic abberation (especially the 10x Victories, which could double as a kaleidoscope!) and flare. I'm not sure if the proliferation of flare was an optical flaw or had more to do with poorly designed housings - but the original Victories were the worst "flare-performers" I have ever used. So, perhaps the new 10x56 FL (which I have not yet tried, but seems to get high praise for brightness and overall performance) have done little more than restore the superior optical qualities that Zeiss had created 13 years ago (negligible chromatic abberation and flare combined with extraordinary brightness and color rendition). And while I'm sure Zeiss has shaved a few ounces off the weight, the FL simply does not (for my money) exude the "cost-no-object" subjective feel of this 13 year old Night Owl - even though both have housings made of glass-fiber reinforced plastic.
I just wanted to pass along some of my observations - FWIW - and I would appreciate comments by any of the more learned optical experts who grace us with their presence in this forum.