Shutter speed accuracy in DSLR cameras
In the Nikon factory tour article, Matjaž pointed out that not all shutters are made equal – some are more precise than others. So, I decided to test my Konica Minolta 5D.
It did pose a bit of a challenge, though – with film cameras, all you had to do was replace the film with a light sensitive device. I decided I'd much rather not take the sensor out of my camera, so I had to measure the reflection off the sensor. It was relatively simple - I got a M42 screw mount to Minolta mount adapter, fitted it with a phototransistor and a light.
First of all, I measured shutter lag, i.e. the time between pressing the shutter release and shutter activation.
It takes 50.6 ms from the moment the mirror is raised to the moment the shutter opens.
And now, for shutter time accuracy:
1/60 s = 16.667 ms. The measured value is, with the measured value of 16.7 seconds. This is surprisingly accurate.
1/125 s, 8 ms. The actual time is 7.96 ms.
1/250 s = 4 ms. The actual time is 4.16 ms.
1/500 s = 2 ms. The actual time is 2.13 ms.
1/1000 s = 1 ms. The actual time is 1.105 ms.
1/2000 s = 0.5 ms. The actual time is 0.508 ms.
1/4000 s = 0.25 ms. The actual time is 0.254 ms.
0.5 s. The actual time is 0.509 s.
1 s. The actual time is 1.01 s
I consider these results to be very good, with a maximum error of about 10%, which is acceptable considering that this is an entry level camera.
The test was performed at room temperature. Note that these are the optimal conditions, with the smallest possible errors. As soon as possible, I'll repeat the test at other temperatures and with other cameras, so stay tuned.