RE: [Leica] M Mount Patents

[Jeremy Kime <jeremy.kime@bbc.co.uk>]

Perhaps the patent for the bayonet mount was in part through the advance of
using a four lug mount, rather than three lugs?
There were other cameras as well which preceded the Leica M in having
bayonet mounts. Take a look at the Steinheil Casca (on Stephen Gandy's
CameraQuest site, for example.

Jem

> ----------
> From: 	Gaifana@aol.com[SMTP:Gaifana@aol.com]
> 
> I'm kind of curious to know how the M mount (or any bayonet mount) could
> be 
> patented after Contax had presumably done it (or introduced it to the 
> public). I know I'm looking with U.S. patent law retrospect, but that
> would 
> have never flown today. Perhaps the only reason it was "patented" in the
> U.S. 
> was reciprocity with Germany, which perhaps had weaker patent standards.
> By 
> 1952, the bayonet mount was present in Contaxes and Rollei filters, both
> of 
> which predate the M3.
> 
> Of course, today, any patent today only lasts 20 years - if today's regime
> 
> had been in place in the 1950s, the Leica clones would have shown up in
> the 
> 1970s. 
> 
> 
> In a message dated 2/16/00 10:04:40 PM, austin@darkroom.com writes:
> 
> << By the way, 1952 US Patent number 2,618,201 is far more interesting.
> That 
> is an invention by August Brohl and Ludwig Leitz of an improvement to the 
> bayonet mount, used subsequently for the M camera, wherein the invention
> is 
> the addition of alignment indicators on the body and the lens.  In other 
> words, this is a patent on the red dots on the lens and body to help align
> 
> the bayonet lugs.  As disclosed, the bayonet mount itself was known and 
> thus already in the public domain by 1951.
> 
> [Austin] My 1949 Hasselblad has a red dot on the body, and a red dot on
> the 
> lense, to aid in mounting alignment.  Perhaps there is more to the patent 
> than the red dots?
> 
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> 
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