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:

Alien from Mars wrote:

Here are my humble suggestions.

FCC- First curtain closes

C-1 - cocking of the 1st curtain

C-2 - cocking of the 2nd curtain

FCO - first curain opens

SCC - second curtain closes

SCO - second curtain opens (should be one of these peaks, really doesn't matter which one).

I also aligned the graphs using 2 first peaks which seem unchanged for all shutter modes.

So the shutter lag in "release lag time short" mode is ~4ms shorter than regular one.

In the EFC mode first curtain moves ~2ms earlier that in fully mechanical mode.

Yes, it is conceivable that the peak you marked is FCC. Whether it is or not should be readily testable (are you listening radsaq?) by comparing ordinary 1/8-second antishock with no antishock. If your theory is correct, we should see an increase in the time between the peak you marked FCC and the one you marked FCO. If not, we should instead see the peak you marked FCO divide into two separate ones.

As to SCO: I think it might well be the case that the second curtain opens quite slowly and gradually and that's why we see "a long peak" (from about 0.120 to about 0.180 in the first graph) in this case. It wouldn't have to wait for the entire sensor to be read but could start opening as soon as the relevant rows have been read. Any other/better ideas?

Here's two more, 1/8s anti-shake at 1/160s followed by a 0s anti-shake shot at 1/40s:

Many thanks. So Alien appears to be right about where the FCC is located, i.e., before rather than after the two big peaks that we think correspond to shutter "cocking" (and which are relocated to the end of the sequence with release lag-time set to short).

Let me add that this may explain why some people have seen an improvement with regard to shutter-shock when setting release lag-time to short. It may be that the problem that regular anti-shock (not the new EFCS version) takes care of is not so much the FCC but the shock/vibrations due to "cocking" the shutter, which are more proximate to the exposure (with regular release lag-time) than the FCC and, if the noise amplitude corresponds to the amount of shock/vibration, more intense as well.

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