Wednesday, 16 August 2017

What are the physical limits of a mechanical shutter?


I've recently found myself shooting a lot of photos on the maximum speed that my camera (a Canon 600D) allows (1/4000). This is quite extreme when thinking about mechanical movements, so I assumed that the digital shutter must be used at that speed. What is the maximum speed that is possible for the mechanical movements and where does the electronic shutter kick in if at all?


P.S. My brain also tells me that there is a possibility that with the amount of light available and the speed being so high that the entire sensor might not actually have to be fully exposed( at one time) to the light source but that a small slit between curtain 1 and 2 should be sufficient.



Answer



The Canon 600D uses a mechanical shutter, and it does indeed go up to 1/4000th rate. There is no "electronic" shutter in Canon DSLR's that I know of. You pretty much nailed it on the head with your 'ps'...the two shutter curtains race over the sensor with a tiny slit (see 'Focal plane shutter, high speed' figure), with the second curtain a minuscule fraction of a second behind the first curtain.



As for maximum speed, I can't say for sure, but pretty high. There are many DSLR cameras that have a 1/8000th or 1/10000th shutter rate, usually "pro grade" models. The high maximum speed of this type of shutter is one of its strengths (leaf shutters, for example, tend to be limited to about 1/500th.)


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