I was fascinated enough by the cool looking SL series binoculars to buy almost all of them in the late 80's, including the 8x56.
The series had a number of quirks. Focus was very slow and awkward and only the 8x56 had roll-down eyecups for eyeglass wearers. The 8x56 also had a very narrow 5.8 degree FOV and the close focus was something like 25-30'. The 10x50 is the only one I wish I still owned. It was a very nice binocular for astronomy.
The photo shows the innards of the 7x50. The 7x42 and 8x56 used an identical design. Optically, it's as simple as a binocular can be; a cemented doublet objective, cemented Porro prism cluster (usually air spaced) and a 3 element Kellner eyepiece, altogether only 8 glass to air surfaces. If you want the highest light transmission this is the way to do it. The same simplicity can be achieved with a cemented AK roof prism. The Zeiss Dialyt 8x56 comes close, but the prisms are air spaced, so it has 10 surfaces. The Swarotop coating of the time claimed 99.8% transmission per surface, but the transmission curve was skewed toward yellow. Peak transmission in the yellow is not so good for low light where the eye is most sensitive to blue/green.
In the old days the term "HABICHT" was applied to everything that Swarovski Optik made: binoculars, spotting scopes, rifle scopes, etc. The old fashioned Porros that we now call Habichts were then called the "Traditional Series" in the US to separate them from the futuristic looking Habicht SL series. The Habicht SLC were originally two small 30mm models and were given the "C" suffix to mean SLCompact, as all the other SL's were 40mm or larger. The SLC designation has remained, somewhat inappropriately given its original meaning, even for large aperture models. I notice that by 2000 the Swarovski catalogue had dropped the HABICHT designation for everything except the "traditional" Porros, rifle scopes and oddly, pocket binoculars.
