Thread: 4.6k Ursa Mini magenta issues?

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  1. #1 4.6k Ursa Mini magenta issues? 
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    There is quite a long thread on the official forums about the 4.6k having a magenta cast and/or magenta-toned vignetting. Any owners here notice this?

    https://forum.blackmagicdesign.com/v...hp?f=2&t=46112
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  2. #2  
    Quote Originally Posted by Akos View Post
    There is quite a long thread on the official forums about the 4.6k having a magenta cast and/or magenta-toned vignetting. Any owners here notice this?

    https://forum.blackmagicdesign.com/v...hp?f=2&t=46112
    No problems whatsoever with my copy of the camera. All is well. : )
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  3. #3  
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    It sounds like their tests are really unscientific but since there is no tinting adjustment in camera some green or magenta pollution would be a little expected.
    Kevin Keller
    Dallas, TX Gaffer & DP
    KKeller.net
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  4. #4  
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    Quote Originally Posted by vicrattlehead View Post
    No problems whatsoever with my copy of the camera. All is well. : )
    Have you done the test of shooting a completely evenly lit white surface? Your camera could still have the issue and it just isn't as severe as the others.

    I'm a little surprised this issue wasn't fixed when we saw it in some of the beta footage.
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  5. #5  
    Quote Originally Posted by RyLo View Post
    Have you done the test of shooting a completely evenly lit white surface? Your camera could still have the issue and it just isn't as severe as the others.

    I'm a little surprised this issue wasn't fixed when we saw it in some of the beta footage.
    To verify, I just shot it on an evenly lit wall at 2500k with and without a lens, and in both cases no visible magenta vignetting or color cast whatsoever, live or on playback. Tried iso 800 and 1600, results were the same.

    Also went through a bunch of clips I have in both ProRes and 4:1 RAW, interiors and exteriors, various lighting conditions, and no issues in any of my clips.

    Using pro Nikon lenses (ais, afd's and g's) with Redrock Micro adapters.
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  6. #6  
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    Quote Originally Posted by vicrattlehead View Post
    To verify, I just shot it on an evenly lit wall at 2500k with and without a lens, and in both cases no visible magenta vignetting or color cast whatsoever, live or on playback. Tried iso 800 and 1600, results were the same.

    Also went through a bunch of clips I have in both ProRes and 4:1 RAW, interiors and exteriors, various lighting conditions, and no issues in any of my clips.

    Using pro Nikon lenses (ais, afd's and g's) with Redrock Micro adapters.

    That's great news, thank you. Hopefully there are more cameras like yours than the ones having issues.
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  7. #7  
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    this user did some tests, there is definitely magenta but the alexa and dragon are green. i wish he used a color chart but i guess he had a short period of time.

    http://bmcuser.com/showthread.php?16...gon-comparison
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  8. #8  
    Not trying to dig up an old topic, but I was doing some IR cut filter tests with a couple of my NDs, and was surprised to see that the 4.6k needs a IR cut even without any ND filtration. First shot is with a Hoya IR cut and second is no filtration at all. Brought both DNGs into camera raw and set the WB and tint the same. I have been taking out a little magenta on all my grades with the 4.6k and wonder if just shooting with the IR on all the time would solve it for me.

    I know it's probably old news to you BM guys, but I'm coming from Sony land where I don't think I used any IRNDs until over 4 stops and even then it was minor. Shooting adjustment for me, for sure.

    Oh, and I did the no lens against a blank wall test and didn't see any weird magenta sensor issues, so it definitely doesn't appear to be affecting all cameras.

    With Hoya IR Cut
    withIR.jpg

    No Filtration
    woIR.jpg
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  9. #9  
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    Quote Originally Posted by mstrouty View Post
    Not trying to dig up an old topic, but I was doing some IR cut filter tests with a couple of my NDs, and was surprised to see that the 4.6k needs a IR cut even without any ND filtration. First shot is with a Hoya IR cut and second is no filtration at all. Brought both DNGs into camera raw and set the WB and tint the same. I have been taking out a little magenta on all my grades with the 4.6k and wonder if just shooting with the IR on all the time would solve it for me.

    I know it's probably old news to you BM guys, but I'm coming from Sony land where I don't think I used any IRNDs until over 4 stops and even then it was minor. Shooting adjustment for me, for sure.

    Oh, and I did the no lens against a blank wall test and didn't see any weird magenta sensor issues, so it definitely doesn't appear to be affecting all cameras.

    With Hoya IR Cut
    withIR.jpg

    No Filtration
    woIR.jpg
    interesting! Thanks for this. I'll check against my set of Hoyas also.
    www.lightformfilm.com
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  10. #10  
    Senior Member Adam Roberts's Avatar
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    Quote Originally Posted by mstrouty View Post
    Not trying to dig up an old topic, but I was doing some IR cut filter tests with a couple of my NDs, and was surprised to see that the 4.6k needs a IR cut even without any ND filtration. First shot is with a Hoya IR cut and second is no filtration at all. Brought both DNGs into camera raw and set the WB and tint the same. I have been taking out a little magenta on all my grades with the 4.6k and wonder if just shooting with the IR on all the time would solve it for me.

    I know it's probably old news to you BM guys, but I'm coming from Sony land where I don't think I used any IRNDs until over 4 stops and even then it was minor. Shooting adjustment for me, for sure.
    This is pretty much the same with the BMCC. Some surfaces reflect more IR than others and so will have a bigger impact on IR pollution. The BM camera have very weak IR filtration in the sensor glass.
    Adam Roberts
    www.adamroberts.net
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