I am currently in a little "reverse porro phase" so two of these cute little things arrived today. Both in absolute pristine condition, apart from some slight dust and one slightly hazy prism.
One is a 7x20 made by "Campbell Hamburg" (Made in Germany and "Est. 1816" on the prism covers) -- though I don't know if that was the actual maker or just a reseller. It seems to be from the 50's or maybe even earlier and it looks like it has rarely been used. It even has BaK4 prisms -- exit pupils look perfectly round.
The other is a "Tasco" labeled skeleton bino in 8x20 -- rather narrow 262ft/1,000yds but still very nice (I am over my EWA-phase as I have enough of them already) optically -- and no stuck diopter or stiff focuser. It works like it was made yesterday except for some slight haze on one side which doesn't affect the view so much that I would open it. Everything else is just in perfect condition. It even still has the rubber rings around the metal eyecups which seem to be missing on many of these. "JTII"-sticker still attached. I just love those reverse porros. People often just seemed to have bought them as a "novelty item" and then never used them judging by the fact that all 4 of the ones I have are almost pristine.
The "Campbell" is even nicer optically and super clean on the inside. Razor sharp views and quite a bit wider than the Tasco.
But when looking through these, I kind of wonder how much actual progress there was in the last 70 odd years apart from the coatings and field flattening? And why did I spend all that money on new roof prism binos? Just kidding. Of course a new roof like my Fuji HC 8x42 is better -- but not by as much as one would expect.
The Tasco has an almost completely flat field -- I don't see any degradation towards the field stop at all. And in contrast to my 7x18 skeleton, where the ocular bridge hits my nose, I can see the field stop in the Tasco as the ocular bridge is just straight across and flat. On the 7x18 J-B93 it is arched upwards (kind of a flaw in design).
The 7x20 is brighter and even slightly sharper on axis but shows more field curvature. Both have a bit of pincushion distortion -- the Tasco slightly less so.
I paid 50€ for the Tasco and a measly 35 for the "Campbell" -- a fantastic price considering the condition and quality.
I am just completely smitten with these little reverse porros at the moment. And especially the skeleton binos are for me as much an optical instrument as they are pieces of art that look lovely on display in a book shelf.
The Tasco has no J-B or J-E numbers anywhere, only a little symbol stamped in the body and "Japan" on one of the prism covers.