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Message: <blockquote data-quote="henry link" data-source="post: 3309737" data-attributes="member: 6806">I barely have time to add two cents to this discussion, but here it is. It's well known that eyepieces are sources of lateral color, some designs more than others, but the only binoculars I've seen with so much lateral color that I wouldn't buy them have been roof prism binoculars of a certain type, including some very expensive "alphas". They share a complex objective design with a wide air space between a negative focusing element and a fixed air-spaced triplet. Objectives with wide air spaces are are known to be another potential design source, besides eyepieces, for lateral color. This kind of design was first used in the Leica Trinovid about 1990 and has gradually been adopted by most makers, with a few exceptions like the Zeiss SF, the first Swaro EL and some Chinese clones including the Zen-Ray ED2, which use a positive focusing lens placed closer to a fixed cemented doublet. Also, old and new binoculars with simple cemented doublet objectives, whether they be roof or Porro, expensive or cheap, don't seem to have much of a problem with lateral color.Adopting ED glass appears to improve, but not completely eliminate, lateral color in the wide air space objective designs. Sometimes even that doesn't seem to work. See the images below of two ED binoculars with very similar pedigrees, Zeiss 8x56 FL and 8x54 HT. To my eye one of these has a perfectly acceptable level of lateral color near the field center, but the other one doesn't.<a href="http://www.birdforum.net/showpost.php?p=3014161&postcount=4" target="_blank">http://www.birdforum.net/showpost.php?p=3014161&postcount=4</a>Henry</blockquote>

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