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There is a setting in menu of my camera wether to use or not to use electronic first curtain shutter. So far I know that using electronic first curtain reduces shutter lag and the noise my camera makes when shooting photos. And electronic first curtain shutter could also be useful to reduce camera vibration when shooting distant subjects, like in moon photography.

So, three good reasons to use it. Should I use it? Is there any disadvantages when using electronic first curtain shutter? There must be, or why else would they even give me a setting in camera menu to choose whether to use it or not.

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As far as I know, it is a flash-only thing. If I'm wrong, I apologise (and would love to know myself!). –  Chinmay Kanchi May 24 '13 at 8:20
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@ChinmayKanchi - essentially unrelated to flash sync. Instead of having the sensor exposure controlled by a shutter opening it is controlled by electronically "turning on' the sensor when it is already light exposed. –  Russell McMahon May 24 '13 at 12:32
    
Alright. My apologies @EsaPaulasto. –  Chinmay Kanchi May 24 '13 at 12:41
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Interestingly, the answers seem to all apply to Sony. On Nikon 1 systems, the flash-sync speed is affected and goes down to 1/60s from 1/250s, so yes it can have something to do with flash-sync. –  Itai May 24 '13 at 13:30
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@Itai - Yes, that kind of effect ln flash sync sure counts as disadvantage. I like answers related directly to Sony cameras, but I hope not limited to Sony only. –  Esa Paulasto May 24 '13 at 17:27

3 Answers 3

up vote 3 down vote accepted

The main disadvantage is that it won't work properly with all lenses (particularly A-mount or other adapted lenses, but also aging E-mount lenses). The mechanical delay introduced by the normal operation of the shutter will allow the iris to close down normally for just about any lens that isn't damaged (or suffering from major dust/grit ingestion); the timing is similar to the mirror flip of a traditional SLR. The EFCS (electronic front curtain shutter) reduces shutter lag to the point that the iris may not have time to close down completely, which can both affect overall exposure for long exposures and cause exposure grading (changes in exposure across the frame) for shorter exposures.

As long as you are using Sony E-mount lenses that are in good condition (or adapted lenses that are manually stopped down), it shouldn't be a problem.

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Stan - my Minolta 17-35mm is arguably aging - maybe 5 years old, but in good order and usually a lovely lens. I think that there may be some explicit difference in the lenses - whether it is "wait for me" signal or a changed timing spec or ??? I know not. This will significantly improve things for me under situations were I want say 1/2000s - 1/4000s in an action situation but an increase in light can push the speed higher. Answer: Use Sony lens or mFCS. –  Russell McMahon May 24 '13 at 13:43
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@RussellMcMahon - I'd suspect a changed timing spec, since the auto aperture on the Minoltas was assuming a mirror by default. (It's been a while, but I'm pretty sure I recall the 9-series Minoltas stopping down when the mirror raised rather than when the shutter was tripped.) Anything made with the SLTs and NEXs in mind would be starting with a different set of assumptions. –  user2719 May 24 '13 at 13:51

Summary:

  • Usually useful. Noise reduction is significant.
    A single muted unsharp mechanical noise may be overlooked in many situations. But the "double tap" of two mechanical curtains is fairly distinctive.

  • May cause problems with

    • high speed motion

    • older Minolta lenses
      The effect at high shutter speed is observed with 2 Minolta lenses that I tried, and not seen with 1 Sony lens. See end.

    • and at very high shutter speeds (~+ 1/8000 s)


Added: See "Yes!!!" at end.
EFCS may cause large under-exposure at very high shutter speeds.
Sample of 1 so far. Mine !!!
Makes sense (see end) but exact basis as yet TBD.


Sony SLT & mirrorless cameras and many Canon EOS DSLrs offer EFCS.

I have a Sony A77 SLT - I use it in EFCS mode and have only used mechanical FCS to compare the modes. For me the main advantage is reduced noise. The SLT fixed mirror and single shutter operation vastly reduce noise compared to a mirror plus 2 shutter actions SLR.

It is implied by Sony that the EFCS may cause image blurring with moving objectcsat large apertures at larger focal lengths. The rationale for this is given below - basically the EFCS has a finite dot writing speed which causes it to be unable to provide a high enough "enable" signal to start sensor light-writing.


From this web discussion.

The Sony NEX5n manual says (lost in translation):

They note that Sony suggests EFCS not be used in some situations eg.

  • When you shoot at high shutter speeds with a large diameter lens attached, the ghosting of a blurred area may occur, depending on the subject or shooting conditions. In such cases, set this item to [Off].

And then provides this plausible discussion:


The first electronic curtain is likely rate limited by the clock it shared with readout. So it can't clear rows faster than it could read them. The second curtain isn't limited by this clock. A mechanical shutter with a sync speed of 1/250 exposing at 1/8000 will move a slit 250:8000 of the height of the frame across it. If the height has 4000 rows, then the size of this slit is 4000*250/8000 = 125 rows. For an electronic shutter, which has a sync speed of say 1/12 (at still resolution; the A77 shoots at up to 12fps, right?) this becomes 4000*12/8000 = 6 rows. At 1/24 it would be 12 rows. So if you're panning with a fast lens wide open, tracking a subject, it's not hard to see how the background could smear.

What they're really saying is that at high shutter speeds and narrow depth of field, turn it off when shooting moving subjects. Sports, wildlife; that sort of thing.


Sony also say:

  • When a Minolta/Konica Minolta lens is used, set this item to [Off]. If you set this item to [On], the correct exposure will not be set or the image brightness will be uneven.

See Stan's comment in this. I'd have thought that the camera could easily add delay if required - say a default delay if the lens is not in the camera's "library". And a user adjustable delay could easily be added.

And discussion says:

Not sure what the difference in lenses is; maybe newer Minolta and all Sony branded lenses have better defined aperture timing, or can go from one aperture to another without passing through an implicit reset state (wide open). Or some other practical difference that matters here.


Yes!!!

My A77 often exposes incorrectly at very high shutter speeds - ay high ISO and bright day when subject matter swings from shadow into bright sun.
In aperture priority mode, as light increases shutter speed increases. As increaseing light moves shutter speed from 1/4000s to 1/6000s the image darkens appreciably and at 1/8000s the image is massively underexposed.

BUT I just tried this with mechanical front curtain shutter and the problem appears to vanish. This testing was done with CFL bulbs and a white ceiling as its 1am here but I'll be trying this in daylight asap.

In this case it may be that the very fine tolerances between electronic turn on and mechanical exposure removal are easily swamped by small error in mechanical timing.
Even at a full curtain traverse time of say 1/250s, to get 1/8000s effective the shutter needs to be open 250/8000 = 1/32 ~+ 3% of the width of the sensor. If shutter edge is "out" by 1% in position the exposure may be reduced by 1/3. A 2% position error gives only 1/3 exposure and a ~= 3% position error gives ~= darkness.

This may well be a calibration adjustment. More anon when/if I find out.

Added 2:

I do not have time now to experiment further at present but:

Exposure with and without EFCS at 1/8000s was good with Sony 50mm, f/1.8 (DT 1.8/50 SAM) even when imaging a CFL light bulb and surroundings at f/2.4.

Exposure problems occurred at 1/8000s with EFCS but NOT with mechanical FCS with

  • Minolta 17-37 f/2.8-4 D -> usually an excellent performer.

  • Tamron 28-200mm, f/3.8-5.6 -> an "only OK" lens overall.

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I'd accept this if you kindly clean it a bit into a more coherent form. It is a bit "messy" as it is now. –  Esa Paulasto Aug 1 '13 at 6:58
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@EsaPaulasto - And it's not for the sake of a ribonned coat. Ret Butler's final recorded response comes to mind :-). Do feel free to use such information as you can gain from the material that I spent the time and effort to provide, should it so suit. –  Russell McMahon Aug 2 '13 at 23:50

I shoot with the Sony A77 and use the electronic first curtain shutter by default.

Pros:

  • reduced audible noise(only second curtain makes sound)
  • reduced lag between trigger and shutter actuations
  • less physical inertia from the shutter and resulting in less camera shake

Cons:

  • some have experienced exposure issues due to timing differences between the shutter and other components(lens aperture speed of stopping down, remote flash, etc.)
  • uneven wear of the first vs second shutter
  • potentially more sensor noise

I've personally not experienced the exposure issues, but that's just with my gear, setup, and use cases. Given sufficient illumination for proper exposure, the added heat/energy from the electronic noise shouldn't be an issue.

I have noticed that using the mechanical first curtain, I do experience more camera shake from the added inertia. The sound level difference is noticeable as well between the two modes.

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