The Fellsphoto Vintage Collection

Testing shutter speeds


Having put film through several cameras only to get various degrees of overexposure I decided not to risk wasting any more until I had a shutter speed tester.

The device I use I found on David Richert's website. It uses the software Audacity, described as a 'Free Cross-Platform Sound Editor'. His illustrated webpage with circuit diagram is here: Sound Card Shutter Tester

If you view his page you will see that he uses a small white LED flashlight. His may well work just fine, but I have to say that I had many problems using a similar setup with poor readings due to insufficient light reaching the sensor, although I suspect that often this was due to not having the light aligned with the lens axis. At one point I could get no readings so concluded the sensor was faulty. I was so convinced of this that I replaced it, but to no avail. As it turned out, the problem was with the light source.

Changing to a mains light was the solution. With the camera placed underneath the light, as you see in the pictures below, the setup is convenient in use and gives consistent strong readings.

Below are some examples showing the setup and the results.


ebay camera buyers will be all to familiar with seller's description: "shutter sounds right at all speeds"

Well, my Bessa Rangefinder certainly sounds right. The Compur-Rapid shutter does indeed have it's top speed of 1/400th giving that confirming, satisfying, hard 'clunk' that it should.



1/400 1/200 1/100 1/50 1/25 1/10 1/5 1/2 1
actual 1/201 1/94 1/65 1/28 1/27 * 1/4.3 1/1.2 2.8

        So: big surprise when we find that the higher speeds are half what they should be!

(slow speeds not all fully tested)


my Voigtlander Brilliant with its Compur shutter 'sounds right at all speeds' - but is, in fact, 1/100th at all speeds. It's perfectly usable ....... providing you don't mind a single speed camera!

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testing my Franka Solida III with Prontor-S shutter and f2.9 Rodenstock Trinar lens



1/250 1/100 1/50 1/25 1/10 1/5 1/2 1
actual 1/250 1/79 1/62 1/26 1/9 1/5 1/2 1

With the cable release socket on the shutter assembly the double exposure mechanism is bypassed.


the data

Previously I'd done ten firings of each speed but found it took too long and generally didn't improve the results, although it is more likely to show up random inconsistencies.

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testing a Zeiss Ercona with Prontor-S shutter and f4.5 Novar lens



This camera has double exposure prevention which requires the 'film' to be wound on each time, an inconvenience that adds considerably to the time to do the test. As it doesn't have its cable release socket on the shutter assembly to bypass the double exposure prevention, the shutter was fired manually from the front actuating lever.


Ercona shutter speeds Audacity screen Ercona spreadsheet
screenshot of test firings showing two measuring bands results spreadsheet

what this means is:


1/250 1/100 1/50 1/25 1/10 1/5 1/2 1
actual 1/180 1/72 1/36 1/19 1/13 1/9 1/4 1.4


the slow speeds (1/10th-1sec) are all over the place, but the higher speeds (1/25th-1/250th) are all roughly 3/4 of indicated

this being the case, compensating on the meter (i.e. setting ISO160 for ISO100) will give correct exposures

Zeiss Ercona


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testing Zeiss Ikon 515-2 with Compur-Rapid shutter and f3.5 Nettar lens

Zeiss 6x9 Nettar with frame finder


1/400 1/200 1/100 1/50 1/25 1/10 1/5 1/2 1
actual 1/155 1/86 1/66 1/31 1/27 1/9 1/5 1/2 1

remarkably, this one is accurate in the slow speed range


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testing my Kodak Retina 1B with Synchro-Compur shutter and f2.8 Retina-Xenar lens



1/500 1/250 1/125 1/60 1/30 1/15 1/8 1/4 1/2 1
actual 1/322 1/201 1/116 1/58 1/33 1/18 1/7 1/3 1/2 1


As the Retina has double exposure prevention, the film has to be wound on before each exposure. One elastic band had to be dispensed with as it fouled the wind-on lever, which on Retinas, is on the bottom of the camera!


This page is rather like a film. It's being developed!

more to come ........




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