Quote:
Originally Posted by chris lewis
I collect old post war binos like yours. Post war Japan produced the majority of classic porro binos produced prior to the Chinese mass producing them over the past two decades. The post war Japanese binos had to meet with stringent Q. and A. standards at the time. Japan produced literally 100's like the yours under different names. I have heard of Zodiac but not had one.
The binos you have are circa 1970's. Yours are a 'standard 7x50' with the 7.1 degree Tfov and a Afov of 50 degrees.[ 7.1 Tfov degrees X's 7x mag. = 50 degrees Afov.] 7x50's give a bright image via there 7 mm exit pupil [ 50mm aperture divided by 7x mag. = 7.1 mm exit pupil] and traditionally work well in limited light and they excell on very dark skies where your eyes can dilate fully to take maximum advantage of the large exit pupil.
They have have a single coating of Mgf. and Bk-7 prisms - as do the majority of binos released post war to the 80's when multi coatings and then F.M.C. became more the norm for Japanese binos. Optically they are good and still give a very usable image - however more modern medium to high end binos with F.M.C. lens and Bak-4 prisms etc. do offer better light transmission, contrast, resolution of detail and reduction of distracting internal secondary reflections / ghostings. They are not W.P. and esp. in humid conditions internal mildew can be very destructive and even eat away the prism and lens coatings as you have found out. For eye glass wearers the E.R. ['eye relief'] can be restrictive also. They are not 'robust' as such either - so do not drop them.
You were brave to dismantle, clean and recollimate them - just make sure you do have pin point star images at night.
So yes there are still very usable binos that are still superior to most entry level Chinese binos.
Chris
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WoW chris!! Thanks for going to the effort of writing all that, it was precisley what I was looking for!!
That made my day, as these were my grandfathers, passed to my mother, then to me.
I would have almost removed a 1/4 gram of mould, dust from the internals, not a mark or residue or shadows / smudge was left when finished. I actually noticed they packed one of the prisms to fix a defect in the chassis of the binos, I fixed that more adequatley too.
I must say though, I personally would have used a coarser thread on the attachments, as the very fine thread they used makes it difficult to start screwing things back together.
Thanks for your time Chris, it is appreciated, as I have found no other info on them.