Thread: Weird Vignette on Red Dragon

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  1. #1 Weird Vignette on Red Dragon 
    Hey guys,

    Got a strange one, im getting some strange vignette on my red epic dragon. As I change resolutions to 6k the vignette will get heavier. Its NOT the lens. I have a set of cp.2 ziess. I use them on my FS7 also and no issues there. Ill attach a photo for reference. Hopefully its a stupid user error but for the life of me cant figure it out.

    https://www.dropbox.com/s/c0pizp2ef4...1.1.1.jpg?dl=0

    Thanks!
    Shaun
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  2. #2  
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    Only looked at the frame on my phone, but I cannot see a vignette. There is however visible light fall off especially to the left. Looks like a soft box on the left, directed to the center/talent and the far left off the studio background getting less light. Was it supposed to be uniform, did you take readings with a light meter?
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  3. #3  
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    Those lenses certainly don't have even field illumination. Point a widish one at a white wall evenly lit, pull up the wave form. You will see a bell curve.

    Nick
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  4. #4  
    Senior Member Patrick Tresch's Avatar
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    R3D?
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  5. #5  
    I use false colour as we have to work so quickly but i can tell you, and i pan around in false colour mode you can see the dark corners. Its like a vignette from a lens 'look' but its not. Really odd. Easy to fix in post naturally.
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  6. #6  
    Whats strange is that they used to be fine. Now i have a 20-30IRE difference from corner to centre or so.
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  7. #7  
    This is jpg with the standard rec709 on it
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  8. #8  
    Quote Originally Posted by Shaun Herbertson View Post
    As I change resolutions to 6k the vignette will get heavier. Its NOT the lens. I have a set of cp.2 ziess. I use them on my FS7 also and no issues there.
    Dragon has a far bigger sensor then the FS7 so naturally your lenses will start to behave more towards the image circle edge on dragon compared to the FS7.

    So very likely its the lens. As it does not really hold up for Full Dragon 6k.

    Post a r3d and its possible to tell more.
    Björn Benckert
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  9. #9  
    Senior Member Tommaso Alvisi's Avatar
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    Which focal length is it specifically?

    Usually digital sensors like telecentric lenses much more, CP2 are not that telecentric and this leads to vignetting and color shift in the corners (magenta in this case).

    A great and underrated set of lenses which avoid this completely is Schneider Cine Xenar III btw.

    Exemption to this rule are generally sensors from Sony (Sony A7s and A7s II, not the A7R), Leica sensors, Canon sensors and Alev III.
    TOMMASO ALVISI | tommasoalvisi.com
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  10. #10  
    Senior Member Nick Morrison's Avatar
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    Quote Originally Posted by Shaun Herbertson View Post
    Hey guys,

    Got a strange one, im getting some strange vignette on my red epic dragon. As I change resolutions to 6k the vignette will get heavier. Its NOT the lens. I have a set of cp.2 ziess. I use them on my FS7 also and no issues there. Ill attach a photo for reference. Hopefully its a stupid user error but for the life of me cant figure it out.

    https://www.dropbox.com/s/c0pizp2ef4...1.1.1.jpg?dl=0

    Thanks!
    Shaun
    It's the lenses.

    We've seen similar issues.

    Remember (as Bjorn points out), the Dragon 6K sensor is much larger than the FS7 - so you're going to see much more vignetting, etc.

    CP2's are modern glass, but some of the designs are older and vignette more than say Sigmas or Tokinas, or more expensive Zeiss glass like Supremes.

    You'll know it's the glass if you stop down to say an F4 or 5.6 and it goes away.
    Nick Morrison
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