What the hell is "flicker reduction" ?

Discussion in 'Olympus Cameras' started by kirschm, Nov 16, 2014.

  1. kirschm

    kirschm Mu-43 Regular

    82
    May 4, 2014
    Germany
    When googling for...

    olympus "flicker reduction"

    (Oly settings menu within 'Display')

    ... I find nothing that really explains what it means.

    1) What does this setting mean?
    2) What are typical situations, where somebody can explain what it means?
    3) Which setting should we choose in order to achieve what?

    Let's limit to stills only, no video... for the time beeing...
     
  2. Growltiger

    Growltiger Mu-43 Top Veteran

    652
    Mar 26, 2014
    UK
    If you live in the USA set it to 60.
    If you live anywhere else set it to 50.
    If you don't know where you live set it to Auto.

    Perhaps it tweaks the shutter speed if it is around that number so that it exactly matches the power frequency and so avoids flicker, which can be very bad with some stadium lighting.
     
  3. christofp

    christofp Mu-43 Regular

    138
    Jul 21, 2012
    Camera will tweak the EVF-exposure to reduce 50/60Hz flickering in EVF (which has around 200Hz refresh rate).

    On thing to note:

    The camera will open or close the aperture to get the correct exposure/timing. A lot of people complain about lens-rattle, most of them don't realize it's caused by anti-flicker.

    Because I have three lenses with loud aperture (25/1.4, 75/1.8 and 50-200/3.5) I have switched flicker reduction to "OFF".

    Chrsitof
     
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  4. gryphon1911

    gryphon1911 Mu-43 Hall of Famer

    Mar 13, 2014
    Central Ohio, USA
    Andrew
    That is correct regarding the power/light frequency.
     
  5. Clint

    Clint Mu-43 All-Pro

    Apr 22, 2013
    San Diego area, CA
    Clint
    From the manual (p 93/E-M1, p 91/E-M10)

    Reduce the effects of flicker under some kinds of lighting, including fluorescent lamps. When flicker is not reduced by the [Auto] setting, set to [50Hz] or [60Hz] in accordance with the commercial power frequency of the region where the camera is used.
     
  6. mronen

    mronen Mu-43 Regular

    74
    Jul 20, 2012
    Does it affect the actual shutter timing or only the EVF refresh synchronization?

    Moshe
     
  7. Leif

    Leif Mu-43 Regular

    98
    Sep 28, 2012
    Germany
    Leif
    It has to be the shutter or sensor reading as well because it influences the final video. If you record a video at 60hz here in Germany, for example, it will look horrible.
     
  8. kirschm

    kirschm Mu-43 Regular

    82
    May 4, 2014
    Germany
    Back to my initial question... I asked the same in a German Forum... the results are not final yet (or better: the thread seems to be dead meanwhile)...

    But there was a well known Olympus guru that recommended to set flicker reduction to 'Off' in order to be on the safe side to get what you see... at least I understood it that way...

    Those familiar with German language... starting Post #16 here: http://www.oly-forum.com/forum/foto...n-für-rauschunterdrückung-und-rauschminderung
     
  9. Growltiger

    Growltiger Mu-43 Top Veteran

    652
    Mar 26, 2014
    UK
    It appears that no one is sure what it actually does. Does it affect the EVF, or still photos, or video? How? Perhaps you can ask this guru if he knows?
     
  10. Tilman Paulin

    Tilman Paulin Mu-43 Veteran

    329
    Jun 10, 2013
    Dublin, Ireland
    For stills it would have no effect, as it it's a setting only affecting video capture.
    Most of our light sources do not emit a continuously equal amount of light but vary their intensity depending on the supply voltage/frequency. (e.g. 110V/60Hz in USA, 220V/50Hz in Europe)
    This is usually not visible to the eye, but a camera recording video can pick it up and it can become a problem when the two are "out of sync". (There will be a flicker in the video / Das Video wird flackern.)


    This thread unfortunately mixes up terminologies. Some people talk about noise reduction (Rauschunterdrueckung), other people about "flicker reduction" (not sure what the German technical term would be... "flicker" would translate as "flackern" z.B. "eine flackernde Lichtquelle"


    Hope this helps a bit? :)
     
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  11. Petrochemist

    Petrochemist Mu-43 Top Veteran

    655
    Mar 21, 2013
    N Essex, UK
    Mike
    I believe Tilman has hit the nail on the head. Personally I rarely shoot video, so I have more use for Flickr reduction - shrinking photos before sharing on-line to reduce bandwidth & perhaps theft.
     
  12. kirschm

    kirschm Mu-43 Regular

    82
    May 4, 2014
    Germany
    Re the Olympus Englisch / German translations... those are the 'pairs' that you see in the menu (or german vs. english manual) when switching back and forth the language. Especially the Flicker Reduction translation is a ton of garbage

    • Rauschreduzierung / Flicker Reduction (what we are talking about here)
    • Rauschminderung / Noise Reduction (the thing about darkframe)
    • Rauschunterdrückung / Noise Filter (the 'classic': JPG noise setting)

    The reason that all those 3 are often discussed in a single thread is obvious:
    1) all settings seem to handle 'noise' (because everything is translated starting 'Rausch')
    2) all 3 'Rausch'-translations in German language mean the same...
    3) confusing, isn't it?

    Those strange Olympus translations are the reason that many German users switch their Olympus to english language.

    But let's limit this thread to flicker reduction only...

    Back to the 'guru': He answered 'turn it off' (we were only talking about stills, not video)...
     
  13. Growltiger

    Growltiger Mu-43 Top Veteran

    652
    Mar 26, 2014
    UK
    But why? If it only affects video, and it helps anyway, why turn it off for stills?
     
  14. kirschm

    kirschm Mu-43 Regular

    82
    May 4, 2014
    Germany
    The 'why' is exactly my missing piece of the puzzle...
     
  15. SojiOkita

    SojiOkita Mu-43 Top Veteran

    620
    Feb 23, 2014
    France
    On my Panasonic 25 mm, it was the cause of "rattlesnaking noise" (you can find some example on youtube).
    Now that it is set to off, never had any problem with it.
     
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  16. kirschm

    kirschm Mu-43 Regular

    82
    May 4, 2014
    Germany
    That's a nice side effect... but beside of all those nice side effects (no rattlesnaking, etc.) I am wondering why setting it to off is best for the final picture outcome...

    Let me translate some statements in the german thread that might lead to some insights:

    "... it can have tremenous impacts, if you don't see that you take pictures at flickering conditions and suddenly at the end of the day you get only black pictures and don't know why"

    And an other speculation/remark from an other user: "exposure measurement in the bright phase, but actual exposure in the dark phase ??!!"
     
  17. Tilman Paulin

    Tilman Paulin Mu-43 Veteran

    329
    Jun 10, 2013
    Dublin, Ireland
    ouch! These are even worse then Photoshop "Smudge tool" -Wischfinger :D
    Yes, extremely confusing and unhelpful translations...


    After reading Reinhard's original statement, I have to correct myself. He is right and it can affect still images. But only with very short exposure times and flickering light sources.

    Up to post 24 he's talking about noise reduction though, only in post 27 he switches over to talking about flicker reduction.

    His point is:
    -the 'flicker reduction' setting not only corrects for flickering in video captures, but also for the flickering that you would see in the electronic viewfinder (you're seeing a video signal in there after all)

    -So he prefers to see this flicker in the viewfinder, so that he is aware of a potential problem. (-> if there's flickering in the viewfinder, he knows that one of his lightsources is flickering and he needs to be careful with short exposure times)

    ---

    My conclusion would be:
    -Switch it to off when you're only shooting stills.
    -Switch it to on when you're shooting video under artificial light sources.

    cheers,
    Tilman
     
  18. kirschm

    kirschm Mu-43 Regular

    82
    May 4, 2014
    Germany
    @Tilman Paulin

    Hm, think I got it... so the risk when shooting under flicker conditions at short shutter speeds is that the short exposure is just at the same moment as the 'dark-flicker-phase'?

    At longer shutter speeds it doesn't matter because on and off an on and off etc. compensate on average?

    And as you said: setting flicker reduction to off does not prevent all this, but is an alert for you that **** might happen... right?
     
  19. Tilman Paulin

    Tilman Paulin Mu-43 Veteran

    329
    Jun 10, 2013
    Dublin, Ireland
    that's a "yes, exactly" to all three questions :smile:

    Flicker reduction on or off won't change anything on your still images. But with "off" you would see flicker in the viewfinder (if there's a flickering lightsource) and be alerted of a possible issue when shooting at short exposure times.
     
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  20. kirschm

    kirschm Mu-43 Regular

    82
    May 4, 2014
    Germany
    OK, now that we (hopefully) clarified theory... how does ist really impact practice?

    I am not a physicist, but I understand by flickering at e.g. 50Hz the following:

    dark... bright... dark... bright... and each dark or bright phase is roughly 1/50 sec?

    This would mean a probability of 50% to either hit dark or bright at roughly 1/50 or shorter shutter speed?

    This would mean that on average every 2nd picture is garbage (dark)?

    I took many pictures under flickering conditions (subway / metro railways stations underground) at roughly 1/50... but never got a problem-picture....?