Potential shutter speed problems

[P3D Tom Martin <tlmartin@xxxxxxxxxxxxx>]

Gary Groose writes:

>The roll turned out to be mostly overexposed, so I will not sweat trying
>to precision re-mount any this time.
=20
To which Dr. T replied in part:

>Some Kodaks have a slow shutter which leads to overexposed slides.

This actually is a very important point that many photographers who use
manually timed cameras (most 50's stereo cameras) frequently overlook.
In a era of computer controlled electronics, the novice stereo
photographer, and a few old timers as well, forget that the time that is
listed on their shutter speed settings is seldom the actual speed that
their shutter is firing at.

It is quite logical to assume that heavily used camera will wear out
parts, and springs will loose their tension, but it is just as likely to
assume that that long passages of time (30 or 40 years is a common age
for stereo cameras) will also cause timing springs to loose their punch.
Sometimes they were not accurate coming out of the factory, and have
never been corrected (quite common on less expensive cameras).

As a user of many old cameras, I found out early on that it was well
worth my money to invest in a shutter tester ($69 I believe is the
current price). I test each camera before I use it, and write the actual
shutter speeds on a piece of tape that I stick to the camera or case. It
is surprising how many times I will find that all of the settings are
really quite close to their printed speed, ...except for one! Shutters
that should go 50, 100, 150 are actually 48, 62, 146. The 50 and 150
speeds are close enough, but the 100, for all practical purposes, is no
longer usable.

I ran across this problem early in my stereo life with a Kodak Stereo
camera that was giving me very inconsistent exposures on my first few
rolls through it. My low light and flash shots all were perfect
exposures (well, close enough :). The full sunlight shots however, were
mostly overexposed. I was very disappointed with these first tries with
a stereo camera and set it aside for a few months to work on other
projects.

After acquiring a tester, and testing several other cameras with it, I
ran the Kodak through its paces. Sure enough, the 200 speed was actually
89 (slower than the 100 speed setting!). Knowing that fact, I avoided
using 1/200 and my next roll had no exposure problems.

Although this is a common problem with Kodaks, I have found shutter
speeds that were off on most other brands of stereo cameras (yes, even
Realists!).

If you only have one or two older cameras and don't want to invest in a
tester, finding someone who has one shouldn't be too hard. Try local
camera clubs, camera repair people, or camera shows. The cost of the
test shouldn't be very high, but it does take about 15 to 20 mins to do
the test and calculations.

If you can=92t find anyone locally with a tester, you can run a test roll
of film through so that you can at least get a feel for camera=92s
accuracy.  To do this, take a light reading of potential test scenes
using a light meter that you know is accurate. Find a scene that gives
you a setting of about 1/25 at f16 for the speed of film that you are
using. Take the photo, and then walk it up. That means the next photo
should be taken at 1/50 at f11, the next at 1/100 at f8, and so on. When
your slides come back, these scenes should all have the same relative
exposure. If one is lighter or darker than the rest, just don=92t use tha=
t
setting when you shoot. If they all are too light or too dark you can
compensate by lying to your light meter about the ASA (or you can do the
same to the Sunny 16 rule). Too light is overexposed, so use a higher
speed ASA rating for that film. Too dark, use lower.

A good craftsman knows his tools, and every photographer should know
what his (or her) camera can and can not do. Shutter speeds are one of
the most frequent problem areas on older cameras, and not difficult to
overcome.

I don=92t know if a slow shutter was one of the problems Gary had with hi=
s
first roll of stereo pics, but I thought perhaps someone on the List
might find some use for this memory jogger when using old cameras.

Tom Martin
mailto:tlmartin@xxxxxxxxxxxxx


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