is center focus. These also ran on 2 AA batteries. They were a 7.5x to 15x electric zoom with a 40mm objective. The exit pupil was 5.3mm at 7.5x and a F.O.V. of 6.25 degrees/336 ft. at 1000 yds at 7.5x. The body was a magnesium alloy. The height was 6 3/4" and the bino (model No. EPZ40) was 44 oz. The electric zoom assembly was a combination of brass and plastic gears.
re: Zeiss 4HF12 binoculars. Having restored a couple of these wonderful instruments, I can tell you that they all show the same high level of craftsmanship. Parts are matched and individually fitted. The prism clusters are very adjustable, which is a blessing for the technician and a hateful curse to the amateur. The tolerances of the eyepiece focus assemblies makes them far smoother and steadier compared to newer designs, and the overall weight of the instrument make for very steady and enjoyable viewing.
Regards to all, Earl
Subject: Zeiss 4HF12 binocular, etc.
From: "Gene A. Lucas" <geneluca@___com.com>
RE: Big Zeiss binos restoration mentioned in List No. 273 -- I might point out that the text re: the big Zeiss binos in Fort Myers, Florida was quoted from the EAS web pages...not from me. I have not seen those binos, unfortunately. Perhaps someone on the list could comment about the Zeiss model no. and perhaps give some additional info (if known)....
RE: Gordon Raynor's List No. 273 note on an article in the September/October 2003 "Home Shop Machinist", p. 24, concerning cutting disks on the lathe. The lathe fixture consists of two circular plates faced with rubber, clamping the material to be trimmed into a disk in between. One plate is held on the lathe spindle, the other pressed up tight with the tailstock ram. One must of course, proceed with caution, using light cuts! Cutting plastic disks will burr up (the plastic melts easily and sticks to the cutting edge) unless using fast turning speed (with increased caution!) and very sharp tools. I have seen other articles suggesting a thin disk could be held with "Super Glue" for temporary fixturing. The part is removed with a light tap after machining.
Cutting Solar Filters -- The above-mentioned technique might be used to cut various size solar filter disks (perhaps for binocular objectives?) out of the newer gold-coated plastic welder's filters, which are a tough, dark plastic material. They are available up to approx. 4-1/2 inches square. I have one here at my desk, "Green Diamond" brand, P/N FS-5H, Shade no. 12 per ANSI-Z87.1-1989 (which is certainly adequate for solar observation), 4-1/2 by 5-1/4 inches (113 x 132 mm) square, about 1/8 inch (0.125 or 3.2 mm) thick, with an approx. 1/8 inch (3-4 mm) raised lip on the edges. Reflective gold coated one side (scratch resistant). Cost about $3.
Machine tool tips: "Home Shop Machinist" and its sister/companion publication "Machinist's Workshop" are excellent sources of tips and information for non-professional hobbyists like me, with good sources of tools, etc. They are published semi-monthly, that is, the two titles alternating every-other-month. Not too much on optics or telescopes, but Glenn Wilson of Denver is an occasional contributor.
Handy Measuring Tools: Harbor Freight Sales (web site: http://www.harborfreighttools.com or see your local store) runs a sale on a Chinese made 0 to 6 inch (zero to 150 mm) metric/english digital caliper every so often for around $20. Comes in a nice plastic case. Press a button and convert the reading from inches to millimeters! And Grizzly Tools (Web page: http://www.grizzly.com) had a cute little 4 inch dial caliper for sale for under $12 when I visited their store in Bellingham, WA this spring. (They also have a Left-Handed digital caliper model.)