Day 42, M6A1 Elbow Telescope
If you collect odd bits of optical junk, you will at some point end up with some military surplus. Today's entry is an M6A1 Telescope Elbow, manufactured during the Second World War by the Bulova Watch Company. My understanding is that these were bolted on to pieces of artillery. There is no means for adjusting the direction of the scope, they were clearly meant to be bolted onto something else.
It's a chunky boi, made from cast iron and clearly meant to be used in the field. It has about a 60mm aperture, of an unknown focal length, but I supect it's probably around f/4 just by the dimensions. The eyepiece is a massive 3" in diameter, and has a deeply knurled knob to adjust focus. I suspect the overall magnification is about 5x, although I have not tried to measure it specifically.
It bears a plate with the following text:
TELESCOPE, ELBOW
M6A1
NO. 1849, G.I.R.
BULOVA WATCH CO., 1944
It has an internal filter wheel that can be set to clear, neutral, red and amber.
Links
The University of Toronto Scientific Instruments Collection has one that appears identical to this one:
Bulova Elbow Telescope Artillery Gunsight – University of Toronto Scientific Instruments Collection
It is my understanding that instruments
like this typically used eyepieces of the Erfle design,
which were five element assemblies that provided good field of view (65 degrees)and sharpness. The company Jaegers
resold large amounts of surplus optics, and I suspect that many an M6A1 was scavenged for this eyepiece.
I believe the focal length of the eyepiece is somewhere around 38mm. The rubber
eyecup on mine is a little bit cracked, but still flexible and generally in good condition.
I didn't spend a lot of time trying to shoot a picture through it, I just held my Canon up to the eyepiece and clicked
on the boring flowers in my neighbors yard. Overall, I would judge the image quality to be good, but not outstanding.
Perhaps in a future installment, I'll post another of my war surplus optics that I like even better.
Hope you all have a good weekend.