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Message: <blockquote data-quote="Hermann" data-source="post: 3647986" data-attributes="member: 4925">Very interesting stuff! Maybe Zeiss actually used the technique described here, albeit in a scope, not in binoculars, in the Zeiss Dialyt 40x60 (<a href="http://www.monocular.info/cz_dial40x60.htm" target="_blank">http://www.monocular.info/cz_dial40x60.htm</a>). The Zeiss 40x60 had an AK prism and came onto the market in 1977, well before phase coatings as we know them arrived in 1988. The optical quality was very good indeed, on a par with scopes using porro prisms like the Zeiss Jena Asiola (<a href="http://www.monocular.info/cz_asiola.htm" target="_blank">http://www.monocular.info/cz_asiola.htm</a>) or the Kowa TS 1. It was also clearly better than its Hensoldt predecessor (<a href="http://www.monocular.info/dialyt40x60.htm" target="_blank">http://www.monocular.info/dialyt40x60.htm</a>) or its smaller brother, the Hensoldt 25x56 (<a href="http://www.monocular.info/dialyt25x56.htm" target="_blank">http://www.monocular.info/dialyt25x56.htm</a>), so much so that the difference couldn't be explained by probably somewhat more modern coatings. In fact, I used the small Hensoldt for travelling for quite a few years and asked Zeiss if they could "upgrade" it which they declined to do, so I sold it. A friend of mine had a Zeiss 40x60 for quite a few years, and I remember we both wondered how Zeiss acchieved such optical quality with an AK prism before phase coatings arrived. Maybe that Gijs' posting explains what we saw.Hermann</blockquote>

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