[rollei_list] Re: Paris-bound with my Art Deco Rolleicord
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Thu, 2 May 2013 10:33:21 -0700
----- Original Message -----
From: "Sanders McNew" <sanders@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Thursday, May 02, 2013 6:53 AM
Subject: [rollei_list] Re: Paris-bound with my Art Deco
Rolleicord
Carlos, you are correct on the focus issue. I bought three
of these bodies -- one in decent shape, and two beaters for
parts. Paul reported that the focus assembly was built of
much lighter material than modern Rolleiflexes, and was very
susceptible to damage from drops and knocks. All three of
the bodies I sent him had this issue -- each bound up a bit
when focus was racked in and out, due to deformities in the
focus assembly caused by damage to the cameras over time.
Unless you're lucky enough to find one of these cameras
that's lived its 80-year life sitting on a shelf, my guess,
based on Paul's observations, is that many of the surviving
users are going to present the same problem now. It's
something to consider when buying an early Rolleicord.
Re flare: The taking lens on my Art Deco appears remarkably
clear of haze and marks. Obviously I didn't use a hood when
I shot the photo -- I was in shade, and thought I could get
away without it. (And I had assumed that the simpler
triplet lens, with fewer interior surfaces, would be less
susceptible to flare.) I'm going to shoot a few rolls with
a hood and see whether that helps to control the flare. I
found an inexpensive Zeiss Ikon 1110 hood that fits the Art
Deco Rolleicord, same 28.5mm push-on design -- I'll try it
out and report back, in case anyone is interested.
Sanders McNew
www.flickr.com/sandersnyc
Regarding flare: There are two sources of flare, one
is from reflection of light from the surfaces of the air
spaced elements. This is present all the time. The other is
from reflection from the internal surfaces of the lens
mount. These are also there all the time but are usually a
problem only if there is a bright light source in the image.
A lens hood does nothing for flare from sources of light in
the image. Its purpose is to prevent reflection of light
coming in the lens from outside the image area. That can
make a considerable difference under some conditions and
little in others. It also helps to prevent reflections from
extra-image light which is reflected from the surfaces
inside the camera. Rollei eventually introduced baffles in
the film chamber to reduce this reflection.
The Triotar is a Triplet with six glass-air surfaces
and relatively low flare. the Tessar has one more element
but its cemented so does not contribute significant flare.
I've found that the greatest cause of low contrast from
older lenses is haze inside the lens. I am not sure what
causes the haze but it cleans off easily with standard lens
cleaner or alcohol. The problem is getting to the surfaces
which usually means some disassembly of the lens. The
difference in image contrast from even a little haze is
surprising.
Flare increases geometrically with the number of
glass-air surfaces. It is quite low for four surfaces (as in
a Dagor), fairly low for six surfaces as in Tessars and
Triplets, and significant for eight surfaces as in Planar,
Plasmat and Dialyte and similar lenses. Above eight surfaces
the flare is sufficient to make coating necessary for these
lenses to be practical.
Beside contrast flare also affects color purity and
saturation.
--
Richard Knoppow
Los Angeles
WB6KBL
dickburk@xxxxxxxxxxxxx
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