I think its slightly unfair to compare the leicas with the vipers when there is a £750 ($1400) price difference tho don't you.
No, I don't, and for at least two reasons. First, for me the aspect of most interest in binoculars is optical quality, so I love optics that are superb AND cheap (e.g. Nikon 8x30EII) but I've chosen to budget for those that are not (i.e. that are expensive) if that's what it takes to meet my standards. Second, and in this particular case, there is an issue of what ED/HD/XD/LD exotic glass accomplishes. There have been relatively inexpensive porros with ED glass that have achieved a low CA view, and there is at least one inexpensive roof (the Promaster Elite ELX ED) that by all reports here at Birdforum does the same. So given that earlier posters in the thread were interested in the prospect of an ED 8x32, my point is that it remains to be seen how they perform, because the full-sized Viper is an underachiever in this respect (as an ED binocular, and as a full-sized roof prism generally).
As for the issue of CA in general, I just describe what I see. What one should buy will take into consideration many factors, and CA might be one of them. The full sized Ultravids are outstanding binoculars, and I've purchased and use them despite their CA. Anyone who wants to is free to do the same with the Vipers. I'm just saying that I'm not impressed with their XD label given that they don't even deliver the performance I expect from a well designed and made nonED.
The human brain does a very good job of eliminating CA from our awareness, but that doesn't mean that just because you aren't conscious of its effects that it isn't robbing the view of information! I notice CA all the time, whether in binoculars or just my regular eyeglasses. I notice the difference in magnification between my corrected right versus left eyes when I look at rectilnear subjects like my laptop screen. I notice changes in the astigmatism in my right eye according to the hydration level of my cornea (it changes very slightly after I take a shower or go for a swim). My eye doctor says that I am hyper-aware of very tiny issues with my eyes, and that I must be pushing my visual system to its limits throughout much of my everyday life, not just when I'm birding or playing with binos. Well, I already knew that. I'm a VERY visually oriented person, and specifically have always been "obsessed" with fine details of texture and pattern in everything that I look at. Perhaps the important thing to realize here is that evaluating binoculars did not make me this way, rather, it is because I'm such a visually oriented person that I became interested in using optics (hand lenses, loupes, cameras, binoculars, telescopes, microscopes) and owning good ones in the first place. Another thing to know is that just because a person can see the flaws in an optical device doesn't mean they can't use it just as effectively as someone who is less aware (it drives me crazy when people say not to look for CA--as if not being aware of it somehow makes you able to overcome its effects!).
--AP
