Shutter-Speed-Tester for your iPhone
I'm a 19 year old student from germany and I wrote a small application for the iPhone wich might be interesting to some of you !
It is called "Shutter-Speed" and it allows you to measure the shutter speed of your camera by analyzing the shutter-release-sound.
After you recorded the shutter-release-sound, the app will display the waveform of this sound. Opening and Closing of the shutter produces two peaks, as you can see in the picture. From the distance between those peaks, the app calculates the shutter-speed and also tells you the deviation from the target value. Afterwards you can save your measurement.
More information here: http://www.echolot-online.de/Shutter-Speed.html
Best results can be obtained from cameras with diaphragm shutter (like TLRs). SLRs or cameras with focal-plane shutter do also work, but they produce a more complex waveform, wich makes it difficult to measure shorter times than 1/60.
I compared the results from this app with an optical measurement and the values are much more exact than you might think, at least for times longer than 1/500.
I would be very happy if some of you try out this app
Lukas, what a great idea for an app !! I was literally about to test the shutter in my newly acquired Mamiya Sekor 55mm TLR lens using my analog CRO when I read this post. One problem is that I am an Android devotee perhaps I'll borrow an iPhone for this , in fact I think I might....
Downloading now :-)
just grabbed it - pretty sweet!
thanks for developing
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I downloaded it too. I'm busy this morning, but I'll test it out later today.
Unfortunately, it isn't measuring the amount of time light passes through the shutter. At slow speeds, it will be sort of accurate.High speeds, less so. On an SLR, there's no knowing what it might be measuring. Good luck, you'll need it.
I've compared results from contraptions like this to a proper test of shutter speeds using a phototransistor and a scope with calibrated time base, these give an approximation at best. Useless for my purposes, which involve measuring how long the shutter actually passes light.
Edit - There are lightmeter apps. Why not write a shutter speed measuring app. that uses the light sensitive element of the cellphone to actually measure the shutter speed, not the sounds the shutter makes, i.e. doing it properly??
Last edited by E. von Hoegh; 09-24-2012 at 11:16 AM. Click to view previous post history.
Shutter-Speed-Tester for your iPhone
I cannot figure out how to use it.
Thanks for the positive feedback, I'm looking forward to your test results
@rich815: well, what exactly is your problem ? you might have a look on the app-website I linked in my post: http://www.echolot-online.de/Shutter-Speed.html
Of course it is only an approximation. But in most cases, it's a quite good one. I compared the values from this app with an optical measurement (photoresistor + audacity) and till the 1/250 the results are quite accurate, the deviation is not more than 1/3 f-stops. Of course this also depends on the camera you are using.
This app isn't designed to measure the shutter speeds at microsecond-level. You won't be able to tell if the 1/250 is more likely a 1/220, but this isn't really necessary as you don't see the difference in your final image anyway. What you can detect, are larger deviations, wich really affect your image. For example if your 1/125 is rather a 1/80.
I had the same idea with the light-sensor, but unfortunately you can't read this sensor without the use of private APIs (forbidden commands). What you could do, is attaching an phototransistor to the mic-input of the iPhone, but I haven't tested this yet.