I find it hard to believe that a porro from 1978 was hitting 92%, at any wavelength. I have a 8x30 Zeiss West from 1978 and don't know its transmission, but in comparison to modern glass it looks like somewhere in the 70% - 80% range. Compared to a modern roof, like my 8x32 Conquest HD, the side-by-side difference in transmission is stark, and the HD isn't likely hitting 92%.
Well, I may be totally wrong but the transmission figures I have seen for older porro's have been in the 70% percent range, so I'm really surprised by the Deltrintem's figure. How would this transmission rate as an percentage average over the visible spectrum?
James, just in case you misread my post, it concerned the Conquest not Deltrintem.
Lee
Arek,
I'm also curious about the very high peak light transmission of the multicoated Deltrintem from 1978. Can you suggest a reason why it measured so much higher than the 7x50 Jenoptem from the "end of the 80s" in the article below? Presumably both used T3M multicoating.
Henry
The Deltrentis/Deltrintem binoculars when introduced in 1920 did, in fact, have 3 lens/5 element Erfles eyepieces. Hans Seeger in his most recent (2015) book, "Zeiss-Feldstecher Handferngläser von 1919-1946. Modelle-Merkmale-Mythos" - pages 144-151, examines this subject in detail. He shows that from 1920-1926 these model binoculars used a 3 lens/5 element Erfle type eyepiece very much like the second one presented in the Albinos' article; from 1926-1932 a modified 3 lens/6 element Erfle was utilized; and, then from 1932-1946 the 2 lens/ 4 element eyepiece shown first in the Albinos' article was introduced which, interestingly, had an aspheric middle (facing the objective lens) element. So when, in 1947, Zeiss Jena modified the binocular to have a 3 lens Erfle, they were actually reverting to the original 1920 design.