Re: Nikon/Canon rf lenses on Leica bodies????

[Michael Volow <mvolo@acpub.duke.edu>]

I'm not an authority on Canon lenses of the late 1960s. However, I do know 
that
Canon made a non-TTL 19mm/3.5 lens for their breech-lock reflex mount. It
was like the early Nikor 21mm/f4, meant to be used with the mirror locked
up and with an accessory finder. There was an adapter to fit it to Canon
RF screw-thread rfdr cameras, with distance scale focussing (non-coupled).
At approximately the same time they also released a rfdr-only screw-thread
version of the lens which couples to Canon rfdrs but requires an external
finder for viewing. This is the lens that I have and which works perfectly
on Leica M's with a screw-to-bayonet adapter. I suspect both lenses have
the same formulation, since the one for the reflex was not for TTL
viewing. The reason I suggest that the formula was retrofocus is that the
fron element is quite large, and the rear element is small and quite far
from the film plane. At least far compared to other rfdr ultrawide-angle
lenses where the rear element is quite close to the film plane. The long
distance from the film plane is what enables the Canon 19mm to be used
with the M6's meter. Although I have not seen a 21mm/2.8 Elmarit, I
suspect some of the same design features were necessary to allow it to be
used with the M6's meter; the meter won't work with the Super Angulons
21/4 and 21/3.5 because their rear elements are so close to the film
plane. 

On Thu, 11 Apr 1996, Jack Campin wrote:

> Date: Thu, 11 Apr 1996 23:39:57 +0000
> From: Jack Campin <jack@purr.demon.co.uk>
> To: leica-users@mejac.palo-alto.ca.us
> Subject: Re: Nikon/Canon rf lenses on Leica bodies????
> 
> Michael Volow wrote:
> > Using a screw-thread to M adapted I often use my Canon 19mm/3.5 on my M6. 
> > It couples accurately. Unlike the Super Angulons, it also works with the 
> > built-in meter (I assume it's a retrofocus design even though being a 
> > rangefinder lens).
> 
> Were there different versions of this lens?  The one I have is in FL mount,
> used via a screw adaptor (with that focal length, who needs a rangefinder?)
> but it projects _way_ inside the camera - it came with an accessory finder;
> the idea was clearly that you used it mirror-up.  This doesn't look like a
> retrofocus design to me, and I can't imagine Canon redesigning the thing to
> be *non*retrofocus specially for use on their SLRs.

At that time there were very few ultrawide ( <21mm ) TTL retrofocus lenses 
for reflexes, primarily the 20mm/f4 Flektagon for the Exacta. Nikon 
introduced their first TTL 20/f3.5 I think in about 1967. (I actually 
bought my Canon 19mm in Japan in '67 or '68.) I think Canon's ultrawide 
retrofocuses came a bit later. 
> ----------------------------------------------------------------------------
> jack@purr.demon.co.uk  -  Jack Campin, 2 Haddington Place, Edinburgh EH7 4AE
> 
> 

Michael Volow, M.D. (mvolo@acpub.duke.edu)
Department of Psychiatry, Durham VA Medical Center, Durham, NC
919 286 0411 Ext 6933