[Leica] Leitz Large Lecture Hall Epidiascope IIIs (was: Time-line: focal length in centimeters versus mi

["Willem-Jan Markerink" <w.j.markerink@a1.nl>]

Forgive me for this repeated posting, just want to be sure that I 
don't miss any audience due to the previously cryptic/non-descriptive 
header:

- ------- Forwarded message follows -------
From:           	"Willem-Jan Markerink" <w.j.markerink@a1.nl>
To:             	leica-users@mejac.palo-alto.ca.us
Date sent:      	Thu, 28 Nov 2002 23:13:30 +0100
Subject:        	[Leica] Time-line: focal length in centimeters 
versus millimeters on projection lenses, Epidiaskop IIIs
Send reply to:  	leica-users@mejac.palo-alto.ca.us

Dear group,

Last week I became the proud owner of what must be one of the most
unique pieces of Leitz projection equipment, the Large Lecture Hall
Epidiascope IIIs[*]....a monstrous steel contraption, 211cm tall, 
64cm
wide, 94cm long, 300-500kg. Needed a full-size horsetrailer with
loading-ramp to haul it home, 5 men for pushing it in the trailer, 3
men for controlled unloading....8-))

Here a preliminary image, lenses removed:

http://www.a1.nl/phomepag/markerink/epimonst.jpg

However, even though I bought it from the university where it had 
been
in active duty many many moons ago, it had been so long out of duty,
pushed aside in a projection room, only recently being forced to move
due to demolishing of the lecture hall itself, that no body knew its
year of build or purchase....it even preceeded the career of the
current janitor ("It's old Jim, but not as we know it...."....8-))

My only time-line reference is the fact that I already had an 
episcopic lens from another IIIs, with different focal length 
annotation; 1:3.5/700mm instead of f=100cm/1:3.5 (both 'EPIS', and
yes, that's 20cm & 30cm lens diameter....the big one is too heavy to
lift to chest-height(!)). Can anyone tell me whether this helps
putting a date stamp on it, at least accurate to a margin of a 
decade?

Serial number of the projector itself is A87052, but I doubt that
helps anything, unless a few known samples around this number exist.

Oh, diascopic projection (up to 4x5", wooden slide-adapters of 
14x14cm) is 110v/1500W (E40 lamp), episcopic projection is 4x 1500W
(with lens/condensor between lamp and paper, each lamp one lens, 
never
seen that in smaller episcopes; probably a must in large lecture 
halls
because of the highly inefficient nature of the episcopic projection
(reflective)). Episcope lenses are 50cm/1:5.7 and 60cm/1:4.5, in a
dual/revolver set-up (for slightly different formats of
slides)....same lenses are used on smaller Diaskop and Epidiaskop.

[*] have yet to find the official German name, did speak to Leitz
folks on the PhotoKina, who agreed with my 'Grossraum Epidiaskop 
IIIs'
translation....further cooperative research is pending, as hardly
anyone working at Leitz today knows much about any
(Epi)Diaskop....either they are able to trace down one or more
senior/retired employees, or I might get an invitation to do research
in the Leitz archives itself....ah, the honor!....:))

See also....

http://www.a1.nl/phomepag/markerink/epimonst.htm

....for the only picture from a IIIs I have found in Leitz literature
thusfar (this one has a 130cm episcope lens, 70cm diascope lens, but
with 'internal' focus, unlike the 'open' screw-collar of both my 
700mm
and 100cm episcope lens (and both diascope lenses as well....only on
an older & smaller Epidiaskop I have such sliding/internal focussing
lenses)  

Only one time before have I seen such a IIIs projector being traded,
in the UK (within some kind of association of historical photography,
tried to track down more info back then, but failed due to their
shielded membership structure (internal auction)).

More about the last range of 'smaller' Diaskop and Epidiaskop (until
late 60's) on:

http://www.a1.nl/phomepag/markerink/diaskop.htm
http://www.a1.nl/phomepag/markerink/epidiask.htm

Bottom line:
If *anyone* knows more about *any* of these projectors, in particular
this huge IIIs, please step forward, in the name of optical/academic
history....;))

- --                 
Bye,

Willem-Jan Markerink

      The desire to understand 
is sometimes far less intelligent than
     the inability to understand

<w.j.markerink@a1.nl>
[note: 'a-one' & 'en-el'!]


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- --                 
Bye,

Willem-Jan Markerink

      The desire to understand 
is sometimes far less intelligent than
     the inability to understand

<w.j.markerink@a1.nl>
[note: 'a-one' & 'en-el'!]


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