[rollei_list] Re: rollei shutter sticking
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Sun, 19 Feb 2006 14:52:07 -0800
----- Original Message -----
From: <FSilberman@xxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Sunday, February 19, 2006 11:00 AM
Subject: [rollei_list] rollei shutter sticking
Just wondering, but generally how long is the shutter stay
timed before the
slow speeds start to lag or stick. I generally get a 2 to
3 of years & I
regularly use the camera & run lots of film through it.
just wondering as I'm not
sure if the tech I use is doing as fair job or not?
Best,
Frederic
There is no fixed time for this. It depends on the design
of the shutter, the kind (if any) of lubrication used, how
much the shutter is used, and the amount of dirt that gets
into it.
Nearly all high quality shutters made for the last ninety
years use a clock-work system to regulate the speeds. It is
usually the sludging of the lubricant in this mechanism that
results in the problem. Modern synthetic lubricants are less
likely to oxidize or to evaporate than those of the distant
past so the interval between needed servicing is much
longer. To some extent the sluggishness can also be caused
by absorption of fine dirt by the lubricant. The rate at
which this happens depends on the atmosphere and the design
of the shutter, i.e., some are more open to the air than
others. Reasonably frequent use of the shutter will tend to
keep it from getting sluggish.
Slow high speeds can also be due to weak drive springs
and to dirt on the shutter blades or in the blade driving
mechanism. Most shutters use a toggle arrangement to drive
the blades through a thin rotating ring to which one end of
each blade is connected. The blades slide against each other
and any residue at all will cause friction and slow down the
opening and closing of the blades. Normally, there is no
lubricant on the blades or the blade driving ring.
Springs are weakened by use. The repeated stretching or
compression of the spring can cause eventual metal fatigue.
The old warnings about leaving shutters tensioned are based
on a misunderstanding about springs. As long as the metal is
not stretched beyond its elastic limit constant tension or
compression will not weaken the spring. It is probably a
good idea not to leave some types of shutters tensioned
because there is force applied to various parts in the
shutter, but weakening the springs is not a problem.
So, as far as time interval, its not possible to come up
with an exact number because there are so many variables. My
Rolleiflex 2.8E was serviced by Harry Fleenor about ten
years ago and the shutter is still right on the nose.
Several shutters I've done myself also have not seemed to
vary over a very long time.
There is at least one reasonably priced shutter tester
available. The one I have came from Calumet, its nearly
doubled in price since I got mine but is still around $100
US. I have not checked to see if its still available, it may
be a victim of digital. Such a tool is very useful for
checking cameras for consistency and accuracy. If you are
doing commercial work I think one is nearly a necessity. It
will tell you immediately if there is a problem.
Keep in mind that the highest couple of speeds on most
shutters are marked for their _effective_ speed at full
clear aperture of the shutter. On Compur-Rapid and
Synchro-Compur shutters the top speed will read about 20%
low on a total open time tester such as the Calumet one.
This is normal but leads some people to think the shutters
are defective.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
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