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Inspired by "Does live view increases the number of shutter actuations?"

This question should apply to most mirrorless system cameras, but I'd like to see an answer that applies to the Olympus OM-D series, as I'm preparing to purchase an OM-D E-M1 Mark III.

As I understand it, the mechanical shutter of a typical mirrorless camera requires two actuations for each exposure in single shooting mode: the shutter closes to end live view, then opens and closes for exposure, then opens again to resume live view. (This may vary depending on shooting mode; for example, burst shooting at the highest speed the mechanical shutter allows only requires one cycle for each shot after the first one, and shooting in electronic front curtain mode requires only one cycle per exposure.)

Do Olympus OM-D cameras properly count this as two shutter actuations in the internal shutter count? This is important because the shutter count would otherwise be inaccurate. (The shutter on the E-M1 Mark III is rated for 400k actuations.)

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To my knowledge, Olympus cameras use a combination of mechanical and electronic shutters. I doubt that they would use the mechanical shutter twice as you described. If nothing else, it would be quite noisy and noticeable.

I checked the information for my Olympus E-M5 camera, which I've been using for over 9 years now. Its internal counters show:

22,066 shutter presses 23,531 shutter actuations

I took one standard shot and verified that both counters got incremented by 1. I expect that I got the extra actuations from special scenarios. I also expect that actuation count to be the same count that Olympus references in their press.

You can also notice that these numbers are way under 100k, so even doubling them would not get you close to reaching that shutter count. I would not worry about the shutter failing. I've never had a camera die on me because of shutter issues.

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So... I stumbled upon this video showing how the Anti-Shock mode works on the E-M5 Mark II and it turns out my question was based on an incorrect assumption.

This assumption is in the way a focal-plane shutter traditionally operates. As implemented on most SLR cameras, whether digital or film, after an exposure, both curtains are returned to their original positions in order to recock it for another exposure. This means the film or sensor can only be exposed in one direction of the shutter curtains' movement. In order to take a picture in live view mode, a typical DSLR camera needs to perform the following steps:

  • Open the first curtain to start live view.
  • Close the second curtain to stop live view, then recock the shutter by returning both curtains to their original positions.
  • Release the shutter to take a picture.
  • Recock the shutter again.
  • Open the first curtain again to resume live view.

This process means that two shutter actuations are required to take a picture in live view. Note that in continuous shooting mode, it may not be necessary to resume live view between shots, reducing the number of extra actuations required.

However, the way the shutter works on the OM-D E-M5 Mark II (and presumably most other mirrorless system cameras, including the E-M1 Mark III) is different. Since there is no optical viewfinder, the camera needs to be able to provide a continuous live view feed, so the shutter needs to be left open during normal operation. As such, the shutter is designed so that it can recock only the first curtain after an exposure, leaving the sensor exposed; the second curtain need not be recocked until the next picture is taken. The steps to take a picture are therefore as follows:

  • (immediately after a previous exposure) Open and cock the first curtain only, leaving the sensor exposed for live view.
  • Close and cock the second curtain to stop live view.
  • Release the shutter to take a picture.
  • Open and cock the first curtain again to expose the sensor and resume live view.

This process only requires one shutter actuation for each picture taken, regardless of shooting mode.

To answer the question, I did end up getting the OM-D E-M1 Mark III last week and I can confirm that it counts only one mechanical shutter actuation per shot in any drive mode that uses the mechanical shutter.

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Mirrorless cameras usually have electronic first curtain shutter that is easy to implement: just gradually release the reset signal to match the speed of the mechanical second curtain.

Therefore, one picture = one shutter actuation.

There is no mechanical first curtain.

That's at least how my EOS RP works; other mirrorless cameras can vary but given the benefits of electronic first curtain shutter, I think many are similar to EOS RP.

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  • I thought the electronic first curtain is an option and isn't enabled by default? – bwDraco Mar 4 at 20:34
  • @bwDraco On an EOS RP, electronic second curtain is an option that isn't enabled by default. It results in horrible rolling shutter effect if enabled. Electronic first curtain is always enabled. Or that's at least how I understand my camera. – juhist Mar 5 at 18:06

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