X hits on this document

Word document

Archives of an email list on the history of binoculars. - page 28 / 150





28 / 150

added bonus of wider fields of view

  So , although personally I find Individual focussing a bit of a pain ( and can think of more interesting uses of rubber than covering binoculars  with  it ) : - )  , for what it's worth my advice is , regardless of tooling costs , go for the sailing and astronomy market and stick with IF and rubber .  

  Regards to all - Kenny .


Subject: New Porro II

From: gordiray@___t

  Why not get the Kamakuras  or one of their or some other Chinese factory to copy the now widely publicized KM  blc  8 x 60  Porro II IF no rubber?  Why no rubber?-because it adds lots or weight which is better alloted elsewhere in the package.  The 7.5mm pupil gives the rotating eyeball more margin for scanning the field  while fully dilated  on a boat, at night, in a vibrating helicopter, etc.  Recall that the eye pupil is not at the center of eyeball rotation.  I have a dkl 10 x 80  Busch type to which blc/eug  oculars from the 80 deg inclined 10 x 80 were hybridized.  Their f.l. is longer than the Busch type 28mm. so the hybrid has magnification lower than 10.  Those 6 element oculars, which seem to have also been used on  the deck mount 8 x 60 (?). synch beautifully with the Busch objectives and prisms, at least subjectively.   I acquired it already hybridized,and it seems more comfortable than the unmodified Busch l0 x 80.   Everybody is selling 7 x 50 .  Ridiculous red blocking coatings are used as gimmicks for distinction. Wide field, big eyepiece, rugged,big prism , glue minimized , rubber free in 8 x 60 or 9 x 70 succeed. High cost? recall the many SLR camera lenses , which require tighter tolerances than eyepieces, were selling for far less than telescope eyepieces of similar dimensions and component counts, even with the focuser included.

--Gordon Rayner


Subject: Porro II Project

From: "James J. Gorman" <jgorman@___omposites.com>

   As one who much prefers the Porro II configuration  to the Porro I, for perhaps idiosyncratic reasons of hand fit and "feel", I am  much interested in the DO Porro II project.  With respect to Mike Rivkin's  request for feedback, I would suggest CF and a pebbled synthetic gray covering  for widest appeal.  The last polished binocular I recall was the ill-fated  silver version of the Rollei/AVIMO 7 x 42.  I most often use IF in daily  walks in the fields with the dog, but most acquaintances who regularly use  binoculars, whether for birding or marine use prefer CF.

  A very nice 7 x 50 Porro II glass was by Kershaw, named "Vanguard".   It seems to me a modernized version of the Ross/Kershaw No. 5 Military glass,  but I have been unable to find reference to it in my admittedly  modest binocular library.  It has a butter-smooth if unusual CF  arrangement, with some internal mechanism, rather than an external bridge  connecting the oculars.  The image is quite excellent, being very bright  and sharp, with only quite minor edge distortion.  The color rendition  is superb, and the contrast excellent without being overbearing.  Mine has  a small collimation error, some minor dirt and fungus, and the left ocular  barrel appears to have been dislodged and imperfectly reset.  With that,  however, it is a truly excellent field glass.  It has the feel of an early  50's design, with a serial no. 53681, though whether Kershaw ran all their  binocs. in the same series I do not know.  I would be much interested if  anyone knows something about this binocular, and wonder whether it is similar in  concept to the DO project glass.  Take Care,  Jim Gorman


  Jim sent some .jpgs, but I am over-committed now & don't have time to ftp them.  The Vanguard is a unique design, with odd curved prism housings that look like they were designed by an art

Document info
Document views564
Page views564
Page last viewedFri Jan 20 02:13:56 UTC 2017