All I can say is that I enjoy the Leica Ultravid/Trinovid line of binoculars and will continue to enjoy them, I will not stack any more BBs regarding CA.
This matches up with some experiences I've had with my Ultravid 7x42. I'm not very good at ID at far distances, so I don't go out of my way looking at specs too far out like hawks way up high. Plus, it's a lower power bino and far away birds can look like specs sometimes anyway. I have noticed a few times colorization seems a touch off with these far distance birds, but when they get closer I'll ID the bird and realize the color did not look quite accurate at the far distance. I'm not talking about color fringing, but just what you mentioned. Close and middle distance birds seem to have accurate color rendering and look amazing through the Uvid Plus. Perhaps if I were to think about getting a 10x for distant birds like for Hawk watching I may go for Zeiss, Swaro or Nikon instead. For the viewing distances I prefer (am comfortable with) the Leica is just wonderful.
I recommend that you get Jerry Liguori's book," HAWKS at a distance: Identification of Migrant Raptors."
Read the forward by Pete Dunne and then familiarize yourself with the book. On page 8 he discusses optics for hawk watching. He recommends using only binoculars. He has used Zeiss 7x42 binoculars for many years because of their wide FOV. None the less he also insists that they be high quality binoculars no matter their power.
Your Leica 7x42 Ultravid will do just fine with its 8º FOV.:t:
ISBN 978-0-691-12559-5 Princeton Press Princeton.edu Quality Paperback.
I actually have that book already ... it's good and I have used it several times to help me with ID. I have it ready for when I need it and think it's well done. I'm just rubbish at Hawks high up in general, but still hope to get better at ID (of all birds). I think someday if I can retire I'll have more time to put into building my ID skills up. I tend to not look high up like other birders and naturally tend to look in trees, scrub, etc.
For instance, I met a lady at this one spot last Sunday who also had a 7x (classic Zeiss Dialyt) and she told me to look up as there was a Hawk soaring high above. I would never have noticed, but she was scanning the skies. We think it was a Cooper's , but agreed we're both rubbish at far distance ID.
... I have noticed a few times colorization seems a touch off with these far distance birds, but when they get closer I'll ID the bird and realize the color did not look quite accurate at the far distance. I'm not talking about color fringing, but just what you mentioned. Close and middle distance birds seem to have accurate color rendering and look amazing through the Uvid Plus...
Grey and overcast is when you really see CA and white skies also.You're going to see detrimental CA when skies are gray and overcast. Trying hawk-watching in these conditions - you would be surprised just how instructive it is, in terms of sussing out objectionable CA.
I have been using an old 10x50 quite a bit and, although distant colours get washed out as noted earlier, my impression after having used this and other single coated porros is that older binoculars can still control chromatic aberration quite well. I gather leaded glass was used back in the day for similar reasons as today's ED glass.
Leaded glass is flint glass, i.e. it has a high refractive index and a low Abbe number (high dispersion) and is or was used in the negative elements of an objective.
Fluorite (calcium fluoride crystal) and so-called ED, HD or SD glasses have low refractive indices and high Abbe numbers (low dispersion) and are used in the positive elements of many modern objectives.