Shutter Speed Tester

A cheap solution – if you already have a computer with a sound card.

Since I started collecting/using old cameras, I realized I'll need some kind of shutter speed tester in order to evaluate the shutter speeds.

Since the commercial testers are either too expensive or not readily available (I live in Croatia), I decided to try and make one myself. I've checked out several plans and schemes, and decided upon the one that seemed the simplest to build – you can find the scheme here: http://www.geocities.com/Yosemite/2131/shspeed.html

In short, the parts required are really cheap and readily available from any electronic parts store. I even bought a generic “device box”, although the box can really be smaller – it needs to be a bit larger than a 1,5V battery.

Here's how it looks like:




The parts required are:

The device is plugged into the microphone input of the computer sound card, and a sound editor program is used – if you're using Windows, CoolEdit (shareware) is a good choice. The important thing is that the program has a precise time scale and wave display.

Put a light source (lightbulb is OK) in front of the lens, open the back of the camera, put the tester with the transistor cell near the shutter, switch the tester on, start “recording” in your software, and then press the shutter.

The recorded “sound” should produce two peaks in opposite directions – one when the shutter was opened, and the other when the shutter was closed. Just measure the timing between the peaks, and that's your exposure time.

The wave form in CoolEdit looks like this:


Actually, that's my Nikon FM on 1/15 speed. In the lower right corner, you'll see that “Length” (refers to selected white portion between two peaks) is 0,067 seconds – which is actually the shutter speed of 1/15.



Here's another sample, using “Audacity” - an excellent (free) sound editor for Linux (there's also a Windows version!):




The above sample (selected portion in the lower waveform) has length of approx. 0,066 seconds, and the speed tested was 1/15 on my Flexaret TLR. The speed of 1/15 should have the length of 0,067 seconds, so the measured speed is just a bit slower than nominal. But for all practical purposes, it's right on the money: the actual difference (0,066 and 0,067) is something like 1%. As a sidenote, many sources agree that a speed difference within 1/3 stop (33%) is acceptable.

Measurements shorter than 1/250 usually get a bit difficult to measure precisely, but will at least give you a good idea of whether the shuttter speed is off.

Here are the internals of the tester: no printed circuit board is necessary, and you'll notice that the wiring is not very elegant, to say the least :-)

After all, if I could put it together, anyone can.




You can see that the “box” can actually be a lot smaller.

Have fun!

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