Smart Phone Shutter Speed Tester

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Carl Hall

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Whilst I was counting down the hours at work today I stumbled across a link to an iPhone app on a Facebook group which claims to be able to test the shutter speed of cameras by measuring the shutter noise and measuring the time. I thought to myself that this seemed too good to be true, but I had a deeper look anyway. Turns out there's an Android version of this app, so I swiftly downloaded it (about £2 something) and set about giving it a go when I got home.

Basically you press the red record button on the app and then fire the shutter on the camera. It then presents you with a fancy little graph showing you all of the noise and sounds that were made as the shutter fired. Then all you have to do it drag two little dots to each high spot in the graph (i.e. opening and closing), and the app will tell you the amount of time between the two dots, which will tell you how accurate your camera shutter is (assuming of course, that the app is accurate!).

I gave this a try on a few cameras that I own, trying to use a few different types: A C220, a Lubitel 166B (which I haven't actually used since I bought it), an RB67, a Praktica L and an EOS 5. I made sure to try each at various shutter speeds, and I found the results to be quite interesting:

(the white box in each series of tests is the speed I was testing against, and the white text above that is the measured time between the blue dots)

Lubitel 166B:

View attachment 43304

Mamiya C220:

View attachment 43305

Canon EOS 5:

View attachment 43308

Mamiya RB67:

View attachment 43307

Praktica L:

View attachment 43306

Before I began testing any of the cameras I had a feeling that some cameras might be easier to test than others (i.e. the C220's leaf shutter and lack of mirror movement would be easier to measure than a Praktica L or RB67 which cause earthquakes), and that seemed to be the case with the results. Interestingly I was not able to find any distinct high points on the Praktica L above about 1/60 as I assume the mirror slapping up and down drowns out any quick movements of the shutter.

I've no idea if anyone will find this interesting or useful, but it wasted away an hour of my evening occupying my mind, so I'm happy. Plus now when I find old cameras in charity shops or at car boots I can give this app a try and see if it tells me anything about the accuracy of the shutter speeds, and if it's possibly worth a buy.
 
The old fashioned way of measuring shutter speeds (at least with leaf shutters) was to photograph a gramophone record with a white strip laid on it - knowing that it was making (e.g. 33 revolutions per second, you could calculate the time.

Shutter speeds though - like much in photography - are not as straightforward as they appear. There are two different ways of looking at a shutter speed: how much light is let through, and how much motion is stopped. And they don't give the same result in terms of fractions of a second. Take the easiest one to explain, the between lens or leaf shutter. It opens up (starting as a small hole and getting larger until fully open); stays open for a certain amount of time; and then closes (the hole getting gradually smaller until completely closed. That much is obvious on the face of it. What isn't quite so obvious is the effect of aperture on exposure. No, not the usual effect - the one created by the way the shutter opens. Suppose you have a wide aperture; it will only be fully exposed for the duration that the shutter is fully open; but a small aperure will be fully exposed for most of the time that the shutter is in motion. The net result is that you get a greater exposure at small apertures for a given shutter speed than you'd expect. This whole topic is referred to as shutter efficiency, and it applies also to focal plane shutters, although it's not as easy to explain why without diagrams. Basically the closer the shutter is to the focal plane, the greater its efficiency.

Hence the amount of exposure at a given shutter speed and the action stopping potential are not equivalent.

Figures on request - but it won't add much to the understanding.
 
StephenM said:
The old fashioned way of measuring shutter speeds (at least with leaf shutters) was to photograph a gramophone record with a white strip laid on it - knowing that it was making (e.g. 33 revolutions per second, you could calculate the time.

Shutter speeds though - like much in photography - are not as straightforward as they appear. There are two different ways of looking at a shutter speed: how much light is let through, and how much motion is stopped. And they don't give the same result in terms of fractions of a second. Take the easiest one to explain, the between lens or leaf shutter. It opens up (starting as a small hole and getting larger until fully open); stays open for a certain amount of time; and then closes (the hole getting gradually smaller until completely closed. That much is obvious on the face of it. What isn't quite so obvious is the effect of aperture on exposure. No, not the usual effect - the one created by the way the shutter opens. Suppose you have a wide aperture; it will only be fully exposed for the duration that the shutter is fully open; but a small aperure will be fully exposed for most of the time that the shutter is in motion. The net result is that you get a greater exposure at small apertures for a given shutter speed than you'd expect. This whole topic is referred to as shutter efficiency, and it applies also to focal plane shutters, although it's not as easy to explain why without diagrams. Basically the closer the shutter is to the focal plane, the greater its efficiency.

Hence the amount of exposure at a given shutter speed and the action stopping potential are not equivalent.

Figures on request - but it won't add much to the understanding.
Click to expand...

That's really interesting - I'd never considered how the mechanics of the shutter and different shutter types affect the timing. I may have to ponder over this more today :)

Carl - I bought the iPhone version of one of the shutter testing apps and a little light sensor probe that pushes into the headphone socket. The app works with shutter sound without the physical device, but actually measures light transmission with it installed. Basically, you open up the back of the camera, place the sensor where the film would sit and operate the camera with it pointed at a light source (I use a table lamp). Honestly, I've only used it to test my Rolleicord and an old OM2 and it's sat in a drawer ever since. It picked up on the longer speeds of my Rollei being a touch short, which is borne out when looking at test negatives and also confirmed the OM2 was buggered...but that was obvious anyway. Probably does nothing that a roll of test negatives couldn't do equally well, but I guess it helps to confirm whether your camera is dodgy or you're just hopeless with a meter!
 
FujiLove said:
That's really interesting - I'd never considered how the mechanics of the shutter and different shutter types affect the timing. I may have to ponder over this more today :)
Click to expand...

As a small hint on pondering focal plane shutters - the shadow cast by an object on a wall gets larger as the object to wall distance increases. If you think of the slit in a focal plane shutter as a negative object, you can imagine that the effect of moving the shutter further away from the focal plane as effectively increasing the slit width - and hence the exposure duration.

As to poor exposure being solely a matter of meter and shutter, that's not necessarily the case either. You lose light to scatter at every air to glass surface in a lens (about 5% per surface if the lens is uncoated, 1% if multicoated (approx)) which is why complex designs needed multicoating to work. And why there used to be a "T" stop system, with the "T" standing for "transmission" so that a T/4 aperture let through the amount of light you'd expect from a non-loss f/4 aperture. And apertures? Ansel Adams found that some of his lenses were wildly out on the aperture markings at smaller stops, and calibrated his lenses so that he knew what the apertures really were.

Ooo, I do like to make things complicated :D
 
After all this science and precision I rely on Our Lady of Blessed Latitude (probably more than I should). It would be interesting to try this on my LF shutters but since I generally never shoot faster than 1s it would likely be academic.
 
I think T lenses are still around in the cine world; just been reading a VSL article about a Samyang/Rokinon lens that comes in f and t versions. I'm guessing that these phenomena have something to do with the odd qualities of a 28-50 zoom lens I have which seems to need a wider aperture than any other lens for the same light!
 
I believe it's mainly because cinematographers have to be very careful of exposure variables; if they switch lenses mid scene and the f/8 on one lens gives a brighter/dimmer image than the f/8 on another, they're scuppered. The T system offers as close to absolute consistency as you'll get.

The construction of zoom lenses is complex, and a lot of the assumptions that you may make about lenses don't hold.
 
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