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Ross No. 5 Mk 4 “Tuna Can” 7x50 (1 Viewer)


Not Sure.
I picked these up today. An interesting looking bin. 7x50 and they are nice and bright. Very clean inside and out. Very solid feeling without being too heavy.

Any idea of how to date them? I'm guessing 1943 or 1944. These were used a lot by coastal watchers. There is a range finder "Graticule" on the right side.


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New York correspondent
United States
Hello Dude,

I have a similar binocular: No.5, mk 5. If they are coated, they were probably upgraded after WWII. The red terminals are for internal electric heaters. Mine has an obscured engraving, ending in 944. !944?

Stay safe.
Arthur :hi:
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Not Sure.
Not exactly birder bins, but they look to be pretty nice for stargazing and general use. I'm guessing they are probably an "armory refurb". They've definitely been cleaned internally, or not seen much action.And the green paint looks to have been touched up a bit. I like them. Unlike anything in my collection.


New York correspondent
United States

A UK collector told me that the No. 5 Mk 5, were as good or better than the wartime Leitz Porro II 7x50. I agree. Another collector wrote that the Porro II design did not lend itself to edge sharpness. The design certainly had better light transmission than contemporary Porro I designs.

Unfortunately, like many military glasses, it was not made for very near sighted users.

Use them well!

Stay safe,
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John A Roberts

Well-known member
Hi rdnzl,

Terence Wayland's extensive research on Ross binoculars can be found on Peter Abrahams' classic Europa site,
see at: http://home.europa.com/~telscope/Ross/

I’ve attached a copy of the PDF on military binoculars. See from page 5 on regarding the No. 5 models
The page starts with an outline of the No. 5 variations:
- see the screen grab: the No. 5 Mk IV was introduced in November 1941, and
- the text then goes on to list serial numbers and production dates


p.s. the home page for the Europa site is at: http://www.europa.com/~telscope/binotele.htm


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