Archived posting to the Leica Users Group, 2000/02/17
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At the suggestion of Jeremy Kime I went searching for Leitz US patents relating to the development of the M, and found several very interesting developments in the 1950s. As time permits, over the next few weeks I will try to summarize (translate from legalese) them. For example, there are several optical glass patents I found, the patent for the Summicron DR, the two patents for the bayonet mount, the design* patent for the overall ornamental shape of the M3, and the patents for the changing viewfinder lines. *A "design" patent lasts 14 years and only covers non-functional ornamental details. A utility patent then lasted 17 years from issuance (now 20 from filing) and covers functional elements. In short, the M clearly was a revolution in technology. The features have more "gee-whiz" than we realize. For example, the 4 lug bayonet (US 2,643,581) was designed so that there would be no vignetting in the corners. Pretty clever! To help, if anyone would like to look at the body of an M3 and see if there are any patent numbers, I would appreciate it. Thanks, Bob Rose "Don't just sit there, invent something!" >>> Jeremy Kime <jeremy.kime@bbc.co.uk> 2/17/2000 3:45:51 AM >>> Robert, I have one at home which dates from the 40s I believe. It seems to place emphasis on the lens throat offering greater diagonal width due to the choice of 4 lugs rather than the more common 3. I'll see if I can dig it out for you. It might be easiest to send it to your address. If you wish to e-mail me that to jem.kime@cwcom.net. best regards, Jem > ---------- > From: Robert Rose[SMTP:] > Reply To: leica-users@mejac.palo-alto.ca.us > Sent: 17 February 2000 01:09 > To: leica-users@mejac.palo-alto.ca.us; dalmy@mindspring.com; > leica@topica.com > Subject: [Leica] The Leica Instamatic and M Mount Patents > > United States patent 4,037,238 (the '238 Patent) by Ludwig Leitz and > Walter Mandler, assigned to Ernst Leitz G.m.b.H., filed 9/5/1975, claiming > priority from German patent DE2445289, filed 9/21/1974. > > This is an improvement patent on a type of point and shoot camera using > "Instamatic" type film cartridges, yet having a zoom lens that is internal > to the camera. Prior cameras of this type required attaching external > lenses to achieve different focal lengths. This invention achieves > internal focusing, so that the external dimensions of the camera do not > change, and allows continuous variation of focal length. Also disclosed > and claimed is a method for focusing the camera. > > In other words, this is for a Leica zoom Instamatic camera. I wonder what > it would have cost! > > What else would you like to know? > > 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. > > Could this be the legendary M mount patent? If so, then I have no idea why > someone did not make a competing bayonet lens for the M cameras until > 1999. > > If someone could point me to any other M mount patents I would be > grateful. > > > >>> David Almy <dalmy@mindspring.com> 2/16/2000 4:49:05 AM >>> > Robert, > > So, for free, tell us what it says! I got the same headache Martin did > and, as usual, still didn't have a clue. > > Thanks, > > David W. Almy > Annapolis > > -------------------------- > > Robert Rose wrote: > > > > Hey, I read this stuff for a living. It is written this way so that we > can charge lots of money to the uninitiated. > > > > Seriously, once you get the hang of it, it does make some sense. > > > > Bob > > > > >>> Martin Howard <howard.390@osu.edu> 2/12/2000 10:58:14 PM >>> > > peter zimmerman jotted down the following: > > > > > > But patent # 4,037,238 is very interesting, particularly when you > > > see the names of the inventors! > > > > > > > On a web site with readable content, on a web page thereof describing > > aforementioned patent, means on said web site for searching said > contents, > > the impression of: > > > > a. a manner of writing said patent text, said manner defining an > > excruciatingly annoying reading experience, said experience leading to > > incomprehension thereof said patent test; and > > > > b. said incomprehension accompanied by headache. > > > > M. > > > > -- > > Martin Howard | > > Visiting Scholar, CSEL, OSU | What boots up must come down. > > email: howard.390@osu.edu | > > www: http://mvhoward.i.am/ > +--------------------------------------- > > > > _____________________________________________________________ > > If you haven't already, visit Andrew Nemeth's excellent website > http://nemeng.com/leica/ where he maintains several areas of interest to > subscribers of this list. If you can, give him some input for his FAQ. > > > > _____________________________________________________________ > > Who will win the Oscars? Spout off on our Entertainment list! > > http://www.topica.com/lists/showbiztalk > > > > _____________________________________________________________ > > If you haven't already, visit Andrew Nemeth's excellent website > http://nemeng.com/leica/ where he maintains several areas of interest to > subscribers of this list. If you can, give him some input for his FAQ. > > > > _____________________________________________________________ > > Who will win the Oscars? Spout off on our Entertainment list! > > http://www.topica.com/lists/showbiztalk > > _____________________________________________________________ > If you haven't already, visit Andrew Nemeth's excellent website > http://nemeng.com/leica/ where he maintains several areas of interest to > subscribers of this list. If you can, give him some input for his FAQ. > > _____________________________________________________________ > Who will win the Oscars? Spout off on our Entertainment list! > http://www.topica.com/lists/showbiztalk >