Shutter Speed Testing
Tips and Trix for Amateurs
by Göran Årelind
Working with old, vintage cameras can be both very interesting and also challenging. In order to conduct an accurate test of shutter speeds, I bought a shutter tester on eBay. The tester itself is quite simple, accurate and not too expensive, below US$100, including the required light source. I recommend buying the light source, it’s rather hard to find a good one. The delivered one has a good intensity that can be adjusted with a potentiometer on the tester (big black knob on the side). Another advantage with this tester is that you get the results in decimal form AND in fractions of a second reading, 1/10, 1/50 etc. To sum up – it’s a fair price for an amateur! The email address of the supplier I selected is email@example.com. He has a wide range of testers, ask advice about which one best meets your requirements.
The real challenge occurred when it came to set up the tests – how to line-up the transmitter and receiver (one LED and one Photo-Cell) properly? The test results are very much dependent on this part. If they are not accurately aligned through the axis of the shutter, one in front of the shutter, the other behind, results will be poor. I’m lucky as I work with just a few different brands of TLR cameras and they are very similar to each other so I can “invent” something suitable for all my cameras.
You don’t need to disassemble the camera for testing. However, to illustrate the set up more clearly, I have used the focusing lensboard assembly from a Yashica 635, complete with shutter and all covers. The left lens is the viewing (top) lens and the right lens is the taking (bottom) lens. On most TLR cameras, there will be a tube fitted to the rear of the taking lens assembly to provide additional light sealing as the lensboard is moved in and out during focusing.
I made an adapter that will fit into the tube to hold the receiver for the shutter tester – the images below show what it looks like.
I used a polymer material called POM, also known as acetal or Delrin. This is strong, but rather easy to work with. It's similar to nylon but harder. It is easy to machine, a bit like brass. For this and the other parts, I used a lathe. I guess that you can get POM in most hardware supply stores. It comes in many different styles, for this part I used a 35 mm rod. Of course, you can use any material that you can work with.
The next two pictures show the adapter mounted inside the tube and finally, with the receiver mounted to the adapter. Be careful to not push the adapter too deep – that’s not necessary and could damage the rear lens element. The “inside” of the camera is now ready.
The next step is to set up the transmitter in front of the shutter, which in practical terms means in front of the taking lens (unless there has been more dismantling). Most TLR cameras have either a bayonet fitting for filters and lens hoods, or for older and/or more basic versions, a plain ring for attaching filters and hoods.
I used an old lens hood with Bay I mount for this first prototype. This fits the majority of Yashicaflex and Yashicas TLRs from 1954 onwards; many other TLRs; most Rolleicords, except very early versions, and most Rolleiflexes with f/3.5 lenses, except very early versions. Of course, a similar adapter could be made for Rolleiflexes with f/2.8 lenses requiring either Bay 2 or Bay 3 mount lens hoods, depending on the lens.
Here are a few pictures of the lens hood based front transmitter adapter.
I made a plastic “washer” and placed it in the bottom
of the hood. Be careful – there is a spring loaded ring inside the hood that
must operate freely (pic. 1).
On the washer, I fixed a short tube with the inner diameter fitting the transmitter perfectly. The whole hood was then filled with epoxy resin guaranteeing that the pipe and washer will not come loose (pic. 2).
Pic. 3 shows the final result.
We now have two adapters guiding the transmitter and receiver in almost perfect alignment and there is very small risk for any stray-light to interfere with the measurements.
The full set-up is shown below.
Good luck with your tests!!