Thursday, July 03, 2014

Shutter actuation count

Although the modern DSLR contains a mass of electronics (and more computing power than the average university had when I was an undergraduate!), it is still in many respects a mechanical device. The mechanisms that flip the mirror out of the way and move curtains across the sensor to make an exposure are very similar to those from film SLRs going back to the 1960s. Inevitably, these mechanical devices eventually wear out and fail. The shutter mechanism in particular is quite complex and delicate and must operate at high speeds to make fast exposures. Camera manufacturers test the reliability of their shutter units and rate then for some expected number of actuations before failure. Canon does not publicise this information and it is not quoted in the specifications of cameras on their web-site but, since about 2009, photo-journalists have been ale to get hold of the figures - presumably direct from Canon. For example, the table about 2/3 way down this 2012 review of the Canon 1DX. To summarise this table, consumer models like the 400D are rated at 50,000; models aimed at enthusiasts like the 60D and 70D are rated 100,000 and professional models are rated several times higher, with the 1D X having the highest rating of 400,000.

Your camera keeps count automatically and internally of the number of times you click the shutter. Some manufacturers (e.g. Nikon) include this shutter actuation count in the EXIF information embedded in each photo, but this is not the case with Canon. In fact it is not easy to discover the actuation count for Canon DSLRs! If you Google "Shutter actuation count" you will find plenty of web-sites that claim to be able to give you this information.

Most are based on reading the EXIF data from a photo taken using the camera. Typically they invite you to take a picture (a small, low quality JPEG will do fine) and upload it. A number of these specifically list a whole load of Canon DSLRs amongst those covered (e.g. this one -which lists "Canon EOS 60D"). If you try it, you will find that they tell you that the info is not available. So why include these Canon models amongst those they claim to support?

Another tranche of sites will tell you about a Windows utility called EosInfo. The idea is that you download and install this program (there is a download link about half way down the page), connect your camera to the computer via the USB lead, turn it on and then run EOSInfo. It should connect to the camera via USB and report the info you want. It claims to work on "Canon DIGIC III/IV DSLRs *except* the 1D* series". However, it has not been updated since 2009 and camera models and firmware move on. With my Canon EOS 60D (firmware version 1.1.1), although it is based on DIGIC IV, on connecting the camera and running EOSInfo, the program falls over with a exception error during the connection attempt.

I have found two methods that DO work on my camera:
  1. Astro Photography Tool (APT). From the download page, download the demo version and install it. Connect your camera to the computer via the USB lead, turn it on and then run APT. It shows a black screen with dim-red text (presumably designed to protect the astronomer's night-sight). The shutter actuation count is shown in the bottom-left corner of the screen.
  2. Magic Lantern. This is a firmware add-on for certain Canon DSLRs. If your camera is supported download it and follow the instructions to install it on your camera. Once installed, it has a Debug menu which shows the shutter actuation count - amongst other data. (I have been experimenting with Magic Lantern for many other reasons and will post about it in due course).
Should I be concerned about my shutter actuation count? I am inclined to look at it rather like the mileometer reading on my car. It gives me a rough idea about when I should expect to need a major service and I would take it into account when buying second-hand. It gives some indication whether it has been heavily used by a commercial driver or kept in the garage by one careful owner! And I would expect the price asked to reflect this. After all, the shutter mechanism can be replaced. It would be a major repair and would probably be expensive - but considerably less that a new camera. However, I have had my 60D since Dec 2010 and the actuation count is roughly 28,000 (in 3.5 years). At that rate of usage, I would expect it to take 12.5 years - that is another 9 years - to get to 100K actuations. Well before then, I think I am likely to want a new camera for many other reasons!