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Confusing electronic shutter modes

 
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Steve S



Joined: 10 May 2013
Posts: 48
Location: Southern Arizona, USA

PostPosted: Thu Mar 01, 2018 11:31 am    Post subject: Confusing electronic shutter modes Reply with quote

The threatened thread on Nikon D850 electronic shutter modes being apparently stillborn, I’m going to offer my imperfect understanding of more-or-less electronic shutter operation on recent cameras. I have no particular qualifications in these matters but have not found on the web a concise summary of the following, so here goes. Corrections, emendations and comments are urgently encouraged.

EFCS aka EFSC, etc:
The progressive exposure of the sensor normally initiated by the movement of the opening shutter curtain is emulated electronically by progressively rendering pixels sensitive to light. The speed and acceleration profile of this must match that of the closing shutter curtain if the exposure is to be uniform over the whole frame. In the case of a mirrorless camera this action can be started without any mechanical operation, since the sensor is normally exposed for viewing and any mechanical shutter is open. In the case of a DSLR, the shutter must have been opened sooner, typically while the mirror is rising, as in initiating live-view mode.

Normal flash synchronization is possible. EFCS exposures have no vibration from the opening curtain, but still have some possible vibration while the closing curtain is moving, but there will be no appreciable effect on the image so long as the exposure is considerably longer than the travel time of the closing curtain.

Silent Shooting aka Silent Photography aka electronic shutter, etc:
Ideally, all the pixels in the sensor could be turned on simultaneously and after the exposure time turned off simultaneously and read quickly without any need for a mechanical shutter, a “global shutter”. Practically, for reasons beyond the scope of this posting, today’s CMOS sensors of interest can’t do that. Rather they must be turned on, exposed, turned off and read row-by-row, sort of simulating a slowly moving focal-plane shutter with a narrow slit. Olympus m4/3 cameras can cover the frame in less than 1/50 second; the D850 and higher-end Sonys take ~1/14sec and the Fuji GFX 50s fully a half second. (See Jim Kasson’s blog, The Last Word.)

Note that even though EFCS may be enabled in the menu system, it is not used in the “silent” modes. Also note that Nikon’s “quiet” modes are something quite different.

Oly offers flash sync in electronic shutter mode, to 1/50sec. Everyone else bags out, no sync. Some Canons sense when a Canon-compatible flash is connected and if the silent shutter mode has been enabled, they disable it. Others just don’t send a sync signal.

Nikon was late to get with the program: aside from a weird, lame, low-rez, JPEG-only implementation on the D4/D5, the D850 is the first Nikon with a fully electronic shutter; as Mike discovered empirically, the D500 does not.
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Lou Jost



Joined: 04 Sep 2015
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PostPosted: Thu Mar 01, 2018 11:45 am    Post subject: Reply with quote

I am very interested in how this is implemented in the D850. I love mirrorless silent-mode cameras for completely vibrationless microphotography. Shutters and mirrors are from the last century. And who wants to buy an expensive camera that is only good for a few hundred thousand shutter actuations? That may have been acceptable in the old days but not for a stacker who shoots four or five thousand pictures a day.

Unfortunately so far the only company that does a good job implementing this is Oly. But if it could be done well on an APS or FF Nikon sensor, I would go for it.

Rumor has it that Nikon will introduce a good mirrorless camera soon...
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mawyatt



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PostPosted: Thu Mar 01, 2018 1:29 pm    Post subject: Reply with quote

Steve,

Thanks for starting this thread. I have no experience with anything except Nikon. As mentioned on the other thread, the D850 can have the flash/strobe bleed-thru if the high intensity optical flash extends into the read out phase of the image capture when in the "Totally Electronic Shutter Mode", which I'll call TESM.

Maybe folks with other cameras with TESM can try to see if they are sensitive to exposure bleed-thru?

Best,
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mawyatt



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PostPosted: Thu Mar 01, 2018 1:56 pm    Post subject: Reply with quote

Lou Jost wrote:
I am very interested in how this is implemented in the D850. I love mirrorless silent-mode cameras for completely vibrationless microphotography. Shutters and mirrors are from the last century. And who wants to buy an expensive camera that is only good for a few hundred thousand shutter actuations? That may have been acceptable in the old days but not for a stacker who shoots four or five thousand pictures a day.

Unfortunately so far the only company that does a good job implementing this is Oly. But if it could be done well on an APS or FF Nikon sensor, I would go for it.

Rumor has it that Nikon will introduce a good mirrorless camera soon...


Lou,

The D850 has the TESM as mentioned, so shutter wear out caused by focus stacking is moved into the electronic realm and practically infinite I would think. I'm stuck with Nikon because of my lens and auxiliary stuff investments, so somewhat biased towards Nikon. However, I do think the D850 is the best overall camera body Nikon has produced, and maybe the one of the best available (I'm sure the Canon and Sony folks have their preference).

Besides the dynamic range and pixel count, the AF is definitely leading edge and Pro Sports performance. Why all new cameras don't have the XQD memory cards is a shame, these are really a dramatic improvement in speed and ruggedness. At first I wasn't too sure about these cards when I got the D500 when it came out, I quickly realized what an improvement they were. I really can't think of much I could ask for except maybe enabling Hot Shoe Flash when in TESM Rolling Eyes

The D850 has just about every base covered for my use, and I can use all my old Nikon stuff Very Happy

Best,
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Lou Jost



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PostPosted: Thu Mar 01, 2018 2:21 pm    Post subject: Reply with quote

Mike, I have also been a Nikon person for the last 40 years, except for a few years in the late 1980s when Canon fluorite super-telephotos were better than Nikon's telephotos, and again briefly when Canon FF sensors were better than Nikon's. But stacking brought me to mirrorless Olympus, which can still use all my Nikon lenses, and those of almost any other brand too. I could never go back to a mirrored and shuttered camera. But I am jealous of the APS and FF sensors. I just wish I could easily use flash with the electronic shutter.

Does a light go on when the camera makes the exposure? If so, a photocell could trigger an external flash, right?
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mawyatt



Joined: 22 Aug 2013
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PostPosted: Thu Mar 01, 2018 2:35 pm    Post subject: Reply with quote

Lou Jost wrote:
Does a light go on when the camera makes the exposure? If so, a photocell could trigger an external flash, right?


That I don't recall any light. There might be a indicator if you tether the camera to a computer, that maybe some custom software could detect. The Delay Trigger Circuit I posted seems to work OK with the D850, and Peter's Digital version should also work. This would give a rough idea of when the exposure was taking place, but as mentioned in my other post it's has somewhat of a variable delay between when the external trigger is initiated and the camera actually starts the TESM exposure.
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Charles Krebs



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PostPosted: Fri Mar 02, 2018 10:51 am    Post subject: Reply with quote

Steve S
Quote:
Corrections, emendations and comments are urgently encouraged.


This can be a confusing topic especially since the nomenclature used by the manufacturers differs, and the manner in which these features are implemented is rarely described in detail.

A couple possible corrections....

I believe the Olympus sync speed with fully electronic shutter is 1/20.

Most cameras (at least all the Canon models I am aware of) that can use an EFSC will revert to using the first mechanical shutter curtain if electronic flash is detected and used. It can happen so quickly that it can be hard to notice.
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Steve S



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PostPosted: Fri Mar 02, 2018 11:18 am    Post subject: Reply with quote

Charles, I only looked at the E-M1 Mk2 manual, which says 1/50 for silent mode, but also 1/20 for some other things; 1/50 does sound fast, given the rest of the industry.

I didn't know about Canons reverting from EFCS with flash; will have to research Nikon, but no time for a couple of days.
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