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  • 4.6k Ursa Mini magenta issues?

    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

  • #2
    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. : )

    Comment


    • #3
      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

      Comment


      • #4
        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.

        Comment


        • #5
          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.

          Comment


          • #6
            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.

            Comment


            • #7
              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

              Comment


              • #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

                Comment


                • #9
                  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
                  [ATTACH=CONFIG]18329[/ATTACH]

                  No Filtration
                  [ATTACH=CONFIG]18330[/ATTACH]
                  interesting! Thanks for this. I'll check against my set of Hoyas also.
                  www.lightformfilm.com
                  https://vimeo.com/suwanchote

                  follow me on instagram @lightformfilm

                  Comment


                  • #10
                    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

                    Comment


                    • #11
                      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 issues on mine. The corners do drop off in exposure but there is no shift in colour.
                      Adam Roberts
                      www.adamroberts.net

                      Comment


                      • #12
                        No magenta anywhere on my camera
                        Blog: http://frankglencairn.wordpress.com/

                        Comment


                        • #13
                          One interesting read that I came across might explain why some struggle more than others in relation to Magenta and is worth noting that Magenta is a color mix.

                          "The spectrum of magenta, a color that can't be made with monochromatic light, could look like this"

                          magentaspectrum.jpg


                          "Both blue and red have a high amplitude, and the mix of blue and red frequencies looks like magenta or purple to the brain."





                          http://www.marktaw.com/design/ColorTheorya.html

                          http://lodev.org/cgtutor/color.html
                          Lotsa Zeon thingos with thousands of cute cores...enough is never enough

                          www.andrewdeme.com
                          http://www.youtube.com/andrewdeme
                          www.facebook.com/andrewdeme
                          http://www.linkedin.com/in/andrewdeme

                          (I reserve the right to edit, modify or delete any content I create anywhere at anytime...it probably wasn't that good anyway)

                          Comment


                          • #14
                            So this is the edges of Benton's image put next to each other:



                            And this is the top and bottom of John Brawley's Leica put next to each other:



                            Benton you are doing just fine! Don't worry about it. John said he never had an issue getting great images from his Leica, and many cameras like Red, Canon, etc have this same thing with non-uniformity.

                            On the topic of overall magenta casts, seems like Sony has the issue enough that someone made a LUT specifically to address magenta casts, maybe someone do the same for the 4.6K?

                            http://www.hingsberg.com/index.php/2...magentakiller/

                            Comment


                            • #15
                              Originally posted by Steven Abrams View Post
                              So this is the edges of Benton's image put next to each other:



                              And this is the top and bottom of John Brawley's Leica put next to each other:



                              Benton you are doing just fine! Don't worry about it. John said he never had an issue getting great images from his Leica, and many cameras like Red, Canon, etc have this same thing with non-uniformity.

                              On the topic of overall magenta casts, seems like Sony has the issue enough that someone made a LUT specifically to address magenta casts, maybe someone do the same for the 4.6K?

                              http://www.hingsberg.com/index.php/2...magentakiller/

                              Exactly. I use an "orange" killer LUT on GH4 footage. Look's like that LUT above does the same thing except dial down magenta.

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