Electronic Front Curtain Shutter and fast legacy lenses with high shutter speed..should be OFF?

Discussion in 'Adapted Lenses' started by shaolin95, Oct 12, 2014.

  1. GabrielPhoto

    GabrielPhoto TalkEmount Top Veteran

    Jul 3, 2013
    So I was just reading about this today and it seems that if I am going to be using large apertures with high speeds, turning it off for legacy lenses is the right option.
    On my quick tests at home, it seems to reduce the "glowy" effect with my 50mm 1.4 for example so it seems to indeed be wise to turn it off but I would love for other users to test and confirm if they see the same thing.
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  2. michelb

    michelb TalkEmount Veteran

    Oct 27, 2013
    Greater Montreal area in Quebec, Canada
    Michel Brien
    Is your adapter closing down the aperture automatically ?

    Looking at Gary Friedman's books on NEX-7 and A7/A7r ( only applies to A7 since A7r does not have EFCS ) and SLT A-77

    His explanations are:
    1) With legacy lenses ( i guess he means those with automatic aperture controls) is that since these were designed for classic SLR's, the time saved by the system using EFCS is the time the lens needs to stop-down to the specified aperture is normally used by the mirror moving up and first curtain shutter closing. If this is the case, the lens does not have the time to stop down completely before the front curtain starts opening therefore giving uneven exposure. So in theory, on a bright day with EFCS on and require a fast shutter speed and small aperture, the lens does not close before the exposure giving occasional overexposed pic.
    1) He also mentions that when using flash in HSS, the same phenomenon happens and you can also get uneven exposure or banding.

    In the A7/A7r guide:
    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 function to [Off].
    When a lens made by another manufacturer (including a Minolta/Konica-Minolta lens) is used, set this item to
    [Off]. If you set this function to [On], the correct exposure will not be set or the image brightness will be

    So both explanations seem to point to the time lag the aperture has to close. This would be useless with legacy lenses used manually ( aperture closed before light measuring therefore no lag to close the aperture since it is already closed to the taking F-stop )

    I had read somewhere else issues about angle of light entering the camera that was influenced by older lens designs mainly wide angle lenses and this would affect corner sharpness.
    I also heard of some TTL flash incompatibilities unless this is set to OFF ( Minolta MFC-1000 with ring or twin light )
  3. jai

    jai TalkEmount Top Veteran

    Feb 4, 2013
    I hadn't heard about this, would be curious as to why?

    The only downside I had heard about with electronic shutters was rolling shutter effects, but that only applies when something is moving through a frame and shutter speed is low?
  4. Jefenator

    Jefenator TalkEmount Top Veteran Subscribing Member

    Nov 23, 2012
    Oregon, USA
    I've seen samples of banding, where the electronic processing for the virtual front curtain doesn't quite match the physical rear curtain. But that was only at or near the maximum shutter speed. (This was back with the NEX-7 - not even sure if it happens at all with the latest cameras.)

    I seldom if ever use those highest of shutter settings, so I go ahead and leave EFC on. (I enjoy the benefits - quicker response and less noise & vibration - a lot!)

    Disabling EFC might be a good idea if you plan on using the highest of shutter speeds.
  5. NkedFatWhiteGuy

    NkedFatWhiteGuy TalkEmount Veteran

    Oct 28, 2013
    Portland, Oregon
    I am curious about this. With E-Mount bodies, you either need to use an adapter for A - Mount lenses (the LA-EAx series), a "dumb" adapter that requires the lens to be manually stopped down for metering as well as for composure and actual capture, or one of those fancy adapters that allows electronic coupling for other manufacturer lens (some of the Metabones I think do this).

    Since the "dumb" adapter does nothing to control the lens at all, I would not expect there to be an issue. With the Sony LA-EAx adapters, there is an SLT mirror and electronics that should control everything as is the lens were mounted to a Sony DSLR. With the fancy - schmancy electronically coupled adapters, well, I don't have any idea what is going on with those... is that where this problem might exist? When someone is attaching a Canon AF lens via a Metabones adapter which provides aperture and AF control?

    Sorry, just trying to understand what is happening a bit...
  6. chrid

    chrid Super Noob

    May 5, 2014
    Yeah I don't know of any adapter that stop the lens down when shooting, thought you just pre-set the aperture and fired away.