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Canon's smart way to reduce 5D MkIII video quality
  • Vitaliy_KiselevVitaliy_Kiselev

    As you may know James Miller ( http://twitter.com/#!/millerandmiller/status/186085781683703809/photo/1 ) removed the secondary OLPF.

    image

    Thing on right side.

    It is not only secondary OLPF. It is ultrasonic dust cleading surface (where all dust settles and is shaken off, look at wires).

    Such thing can be used as AA filter if switched on (it is ultrasonic, but it can slightly shake sensor, hence AA effect). May be some optical effect is used.

    So, it looks like it's action for video can be switched off with firmware change. No need to disassemble whole thing.

    Idea from: http://www.luminous-landscape.com/forum/index.php?topic=62429.0

    P.S. I edited post slightly.

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  • 23 Replies sorted by
  • vladnikvladnik

    Does anybody still thinks that c300 has some kind of magic sensor ... just s35 crop... same story as af100 "this is totaly new sensor it has no any conection with gh1 " really? same tech ....

  • Vitaliy_KiselevVitaliy_Kiselev

    OF course all could be slightly more complicated, but the main idea is the same.
    You are using ultrasonic vibrations to get AA filter for video.
    So, in worst case (no firmware change) it must be enough to remove contacts, not thing itself.

  • vladnikvladnik

    i think that is still aa filter as a part of ultrasonic sensor cleaner plate.... canon use two olpf one for x other for y axis blur... i think that sensor difference is that c300 use faster readout ...

  • Vitaliy_KiselevVitaliy_Kiselev

    @vladnik

    Can you provide me credible source of this information?

  • vladnikvladnik

    yes... http://www.imaging-resource.com/PRODS/E7D/E7DA4.HTM i dont do guessing ... :)

  • Vitaliy_KiselevVitaliy_Kiselev

    @vladnik

    Where it says that one is for x and other for y axis? May be I missed it?

  • vladnikvladnik

    there other source but i dont have time to find it ... google is all over 5d mark III removal ... its little chaotic... nevertheless there are two olpf filters... it cant be just firmware solution... when i find time i post....

    PS:good 1. APRIL joke VK....

  • Vitaliy_KiselevVitaliy_Kiselev

    Quotes:

    Split Anti-Aliasing Filter

    Rather than introducing a separate cover glass into the optical chain, Canon has split the Canon 7D'S anti-aliasing filter into two parts. One element sits right above the sensor, while the other is positioned further away. It's this outer element that's vibrated during the cleaning cycle.

    In describing the technology, Canon notes that the outer anti-aliasing element is positioned further from the sensor surface (a millimeter or so) than is normally the case. This greater distance reduces the effect of any dust that does adhere, by making the shadow cast by each dust particle larger and softer-edged.

    image

  • vladnikvladnik

    http://www.sensorcleaning.com/lowpassfilter.php its little different because is older design d200 but same as canon ... dual olpf work that way ... but that is not important for this subject... what is important is that u cant do this with any software hack ...

  • Vitaliy_KiselevVitaliy_Kiselev

    @vladnik

    Thanks for links. Interesting.

    Yep, it is OLPF used also for dust cleaning.

    But they somehow use it for video. As no other way OLPF filter tuned for high photo frequency can so much affect video.

  • vladnikvladnik

    but there is something strange with canon philosophy... looks like that they are so afraid of moire and aliasing so they put too aggressive olpf ... even in photo mode images look too soft .... in theory it should not affect video ... but i saw images from gh2 with olpf removed and they look sharper than c300 ... strange .. but maybe when u do proper image scaling it does makes difference ... u start with more resolution..

    just look f3 vs fs100 .... same sensor but f3 got much better resolution ....

    http://produktdbimages3.slashcam.de/camcorder-testergebnisse_testbilder_luminanz_aufloesung_211.jpg

    http://produktdbimages4.slashcam.de/camcorder-testergebnisse_testbilder_luminanz_aufloesung_204.jpg

    1. f3
    2. fs100 hor resolution...

    http://provideocoalition.com/images/uploads/FSCSRW-F3.jpg
    http://provideocoalition.com/images/uploads/FSCSRW-FS100.jpg

    f3 got more resolution but more moire ... when u got two cameras with same sensor but one got more resolution and more moire and aliasing that means weaker olpf...

  • Vitaliy_KiselevVitaliy_Kiselev

    even in photo mode images look too soft

    Anyway, high frequencies causing aliasing for photo and video are quite different. If you tune filter for video it won't make slightly softer photos, they'll be really very very soft.

    in theory i should not affect video

    Yep. Only in some subtle way.

  • vladnikvladnik

    yes but olpf is made for sensor pixel pitch not output resolution... other ways all hd video from dslr would aliased horribly... i would try to remove aa filter from my gh2(little experiment)... but i need to find cheaper way .... maxmax is too expensive....

  • Vitaliy_KiselevVitaliy_Kiselev

    yes but olpf is made for sensor pixel pith not output resolution...

    Words look weird. It is tuned according to native sensor resolution (also taking into account that it is bayer sensor). As you can get exact frequencies that cause aliasing.

    other ways all hd video from dslr would aliased horribly

    Oversampling can help with aliasing, and this is exactly that good HDSLR are using.

  • bwhitzbwhitz

    @vladnik "Does anybody still thinks that c300 has some kind of magic sensor ..."

    Yes. Go visit any other forum on the web. They all believe the C300 uses a special magical sensor.

    And not only does this magical sensor have 12 stops of DR... but it actually reduces the DR of any other camera within a 100 yard radius to make you feel even better about yourself.

  • vladnikvladnik

    @bwhitz how many stops of dr c300 reduces other cameras ... if its more than 3 stops i'm all over it ...

  • brianlucebrianluce

    Wait, are you guys trying to say the Magic Sensor is better than the Big Thing? Hope not as I've already preorded the Big Thing at B&H.

  • davhardavhar

    …but, but doesn't everyone need to feel better about themselves…or just me, I mean you

  • RamboRambo

    You all need to read this thread http://personal-view.com/talks/discussion/2752/about-forums#Item_18

  • johnnymjohnnym

    Then shouldn't we be calling Canon for a firmware upgrade without this thing?

    I mean : releasing teaser videos prior to release without this thing, then selling the 5D mkIII with this thing, isn't that technically called fraud?

    I know whom i'm going to call tomorrow.

  • brianlucebrianluce

    Can someone explain how removing an anti aliasing filter gives less aliasing? I don't get that part of it.

  • vladnikvladnik

    @johnnym its not a fraud thats canon standard olpf design... we already resolve that (see above posts) but why they probably shoot promo without it its another question.... @brianluce who sad that ? no olpf more aliasing ....

  • brianlucebrianluce

    @vladnik I'll double check but I could have sworn the original blog claimed sharper image and less aliasing.

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