A perfect solution for binocular dew shields
Posted 19 December 2012 - 09:20 AM
I think I have found the perfect solution in the form of automotive silicone rubber tubing. I bought two 250mm lengths of black 90mm diameter silicone hose from eBay vendor mrsilicone as it was *lot* cheaper than from the website at GBP16.92 including P&P (almost half the price).
I thought 250mm would cause vignetting, but I don't see any indication of that at all.
Posted 19 December 2012 - 07:14 PM
Another way, which I have used, is foamed core, solid skin ABS Drain Waste Vent DWV pipe . ( Is it also used for electrical conduit? I do not recall. A trip to Home Depot, Lowe's, Ace, etc. , or similar big box home repair outlets would give the answer). Larger sizes than 4 inch diameter require a trip to specialty suppliers, as I recall.
Two handsaw cuts, about 3/8 to 1/2 inch apart, parallel to the axis of the pipe, remove a thin, long piece. The tube contracts slightly from this treatment. That gives spring action which allows fitting the tube to a range of telescope/binocular tube outside diameters.
Accurate diametral crosscuts are easily made with use of a miterbox handsaw guide.
The inside can be roughened with sandpaper and/or flat black painted, or lined with black velvet or flocking or foam, etc. The outside can be made uniform with a solvent wipe, such as MEK , acetone, lacquer thinner, etc.
The slot can be facing down, for dew drainage, or in opposition L-R in binoculars with IPD clearance issues, such as the WW II Busch design FLAK 10 x 80 with 45 degree inclination.
It seems that the foamed core ABS DWV tubes are almost certainly lighter than the suggested silicone rubber hose.
Posted 19 December 2012 - 07:28 PM
Posted 20 December 2012 - 07:57 AM
I tried to upload a picture, but even at 640 by 480 it was 211kB and was rejected - Grrr.
I've put it on my website:
Oh yes, the black thing fastened to the central rod is a "red dot" type reflex gun sight attached to a barrel mount type Weaver/Picatinny rail.
Posted 30 December 2012 - 04:26 PM
Posted 30 December 2012 - 04:43 PM
I have found that a light weight cardboard makes a good dew sheild.
Yes, I found the cylindrical cardboard containers from corn meal and such are the perfect size to fit my 16x70s. Take out the bottom, paint them flat black and they're ready to go. They even come with plastic objective covers!