What else is happening before the first curtain on E-M1?

Started Mar 31, 2014 | Discussions thread
Anders W Forum Pro • Posts: 21,468
Re: Shutter video

radsaq wrote:

Anders W wrote:

radsaq wrote:

Anders W wrote:

radsaq wrote:

If the shutter is cocked and then reopened immediately before the sensor is reset, doesn't that mean the entire process could be done in the same time that a normal shutter cycle occurs? The shutter will normally be waiting some number of milliseconds in the cocked (closed) state to let the sensor reset happen before it opens. As far as we can surmise, it's not, and so that has effectively freed up that same interval to be used for the same step, just in a different order. Right?

I would hope you are right but I am not so sure about that. I don't think the first mechanical curtain really needs to wait for the sensor to reset, at least if they've programmed things optimally from the beginning. It will take the mechanical shutter about 1/320 s to close its first curtain (since that's about how fast the blades can move on the E-M1) and in order for the EFCS to sync with the second curtain, the sensor must have the capability to reset within the same interval.

We also have the observations to which I link below from another thread:


So a slight delay compared to mechanical shutter only (but less than the 1/8 s minimum of earlier anti-shock settings) seems likely at this stage. That said, I'll be more than happy if anyone can prove me wrong.

Here's a comparison of the sound of two 1/160s exposures in manual/MF with IS off. The EFCS is on top:

Looks like it's an additional 25ms of shutter lag?

Aah, many thanks for that! Very nice test and very nice results! As I said, I would have preferred to be proven completely wrong, but a delay of only 25 ms comes close enough for me to be happy. That's only 20 percent of the minimum delay previously available with anti-shock (125 ms) and with close to complete rather than partial blur elimination!

Two follow-up questions:

1. Is the zero-point on your time scale an absolute one, i.e., does it conform exactly to the time when the shutter button is fully depressed? If not, is there any way you (or anyone else) can manage a test that let us see the absolute shutter lag times (time between shutter button pressing and actual exposure)?

I am thinking here not only or primarily about the impact of the EFCS (where we now know we need to add about 25 ms) but also of the short release lag-time setting. One thing that still puzzles me is that Imaging Resource couldn't see any effect of that setting in their measurements and even claimed that it sometimes increased the lag slightly. See here:


Nearly the same story on the E-P5 where they (probably incorrectly) speculated that the short lag time setting was accomplished by means of EFCS:



Since you appear to have everything set up nicely for testing this by means of sound profiles, could you please check it out.

Again, many thanks for the contribution you already made as well as for the additional ones you might be able to provide.

I wish I could claim any sort of sophistication, but I simply held my smartphone up to the camera, snapped a couple shots, then imported them into audacity and trimmed them until they roughly lined up (note: they're definitely not quite lined up :-)), followed by an amplify. I believe the first small bump in each is me actuating the shutter release, but I could be wrong.

Well, this is a hard part. There is the possibility of enabling the beep on shutter press but I am not sure how far that will take us since we don't know how quickly the beep is issued after the button is pressed under this or that circumstance. If you have a remote, you could possibly try holding that close to the smartphone and coming down on the button quickly and violently. Anyone have a better idea? I am not at all sure mine is any good.

I'm also somewhat confused as to what's actually happening in each case. Is the exposure happening during the third and fourth large blips (055-080 for EFCS, 055-060 for MFCS)? Someone else feel free to copy and label the screenshot if you're confident about it.

This is my interpretation. If anyone else thinks differently, please feel free to offer an alternative view.

0. Shutter "cocked" (prepared for action)

1. First mechanical curtain closing (for sensor reset without EFCS) and opening (for exposure without EFCS)

2. Second curtain closing (to end exposure and read the sensor)

3. Second curtain opening (to resume live view)

Furthermore, it appears as though the short release lag option is only cutting down the time to exposure by 5-10ms (from about 40ms to 35ms or so?). Useful to have options, but probably not worth the battery drain for most people.

Well that's one of the interesting questions here. You might be right that the time saved is very small but ...

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