Thread: Alan Roberts lab tests URSA Mini 4.6k

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  1. #11  
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    Quote Originally Posted by Taikonaut View Post
    Alan Roberts test shows just over 14 stops of DR in RAW.
    How does his test for the the Red Dragon sensor compare?
    His report on the Dragon seems to indicate 14 to 15 stops of DR (with some fuzziness regarding his opinion of the usability between the 14th and 15th stop).

    https://tech.ebu.ch/docs/tech/tech3335_s16.pdf
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  2. #12  
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    Quote Originally Posted by david evans View Post
    I don't understand what kind of post processing he thinks is necessary for the UM4.6k. Adjusting levels and white point to bring the log into rec 709 space? Or is he saying the gamma is not correct, which makes me curious to ask, what sort of correction could be made. I've seen that pink issue he talks about but it only happens when i'm not using my IR filter (an absolute necessity for this camera).
    I think it's the kind of "processing" normally referred to as color correction, which everyone here takes for granted but which isn't taken for granted in the broadcast world, for which Alan Roberts evaluates cameras. Canon C300II gets his full praise, because the footage is correct right out of the camera, where the same result with the mini depends on adjustment in Resolve.

    It's hard to tell for sure from the summary, but the pink skin tone and over-saturation criticism seems to apply to shooting in rec 709, which of course nobody does.

    Alan Roberts evaluates cameras for performance standards which aren't meant to relate to cinema aesthetics. 35m Film stocks from the 70s, 80s and 90s likely wouldn't qualify at Tier 1 or 2 because they'd be far too noisy, as well as inaccurate color.
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  3. #13  
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    Colour comments aside, I did appreciate his findings regarding sharpness and raw versus ProRes and controlling noise. But testing a camera against broadcast specs isn't going to be the final word and he concedes that in his summary that includes both the burger and the fries!
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  4. #14  
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    My take reading this article which is only re-reporting Alan's test, is that a lot of his comments about the colour and look of the camera comes from using the VIDEO encoded space, not FILM. VIDEO has always been BM's own look for a pre-graded image, and it appears to me that the comments about the colour are in the context of comparing it to an expectation that VIDEO is REC709....it isn't.

    Also, it would appear to be somewhat confusing as to if all his testing was done with windowing / crop mode ON, or even that the full sensor / supersampling of the 4.6K field was used.

    We don't know which firmware was tested. I know that things changed a bit post 3.0 for example.

    Be great to see the ACTUAL test results rather than an article about the test. But we need to remember that these tests are done for a BROADCASTER's point of view.

    I also find it interesting to note that it was a surprise that ProRes, as a side effect of compression, mitigates some of the aliasing, something many of us have known for some time.

    JB
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  5. #15  
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    Quote Originally Posted by Frank Glencairn View Post
    It's like testing a film camera, without considering the stock and lab process.
    If you have a raw camera, "developing" in post is a integral part of the process.

    Would somebody tell Ansel Adams, that he needs to hand of his material, or would the result be better, when he handles the lab work?
    "Handing off" material is a ENG/Broadcast habit, nothing to do with cinematography.

    And yeah, IMHO every cinematographer should be able to "develop" his material in post.
    So under that premise then, would you not take a gig that required you to use that camera and hand off footage at the end of the day? I know many talented DPs who don't do their own looks and transcoding after the shoot wraps. It's typically done by a DIT or a lab. Which is certainly a common workflow from high end commercials to features. But I have to imagine that there are people out there using the UM4.6 that don't have that luxury and need to hand off baked ProRes and probably some of those projects only go through a quick CC. There's quite a large market out there besides cinema and high end TV. Certainly can argue whether it's the right camera for some of those other jobs, but I'm sure some people are trying to use it that way. And I think Alan was aiming for those who have to deal with broadcast specs and handing over footage without doing your own processing.
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  6. #16  
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    Quote Originally Posted by stevesherrick View Post
    So under that premise then, would you not take a gig that required you to use that camera and hand off footage at the end of the day? I know many talented DPs who don't do their own looks and transcoding after the shoot wraps. It's typically done by a DIT or a lab. Which is certainly a common workflow from high end commercials to features. But I have to imagine that there are people out there using the UM4.6 that don't have that luxury and need to hand off baked ProRes and probably some of those projects only go through a quick CC.
    I think the point is though that it's pretty easy to do a "better" version of what BM have done with VIDEO as a LUT if the footage is being transcoded later. And anyone who calls themselves a Cinematographer, DP or a camera monkey should be able to do a better LUT that suits their own tastes. VIDEO isn't great and I would never use it but I have a few LUT's that would easily do a better job in that kind of scenario and it's VERY SIMPLE to make a LUT in this workflow and address this.

    No commercial I've done has even been anything other than LOG originated then graded later. I think it's only broadcasters, and event type work that needs it to actually look good right out of the box without anything else happening.

    JB
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  7. #17  
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    I agree, all but news and a few outliers maybe will want LOG footage anyway.

    I wonder, does the new firmware allow you to record with a user LUT, or only display the result of it on the screen?
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  8. #18  
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    Evaluating raw DR using 4:1 is probably a mistake. He should have used lossless raw. The way BM does lossy raw compression shaves off a bit of DR.
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    Doesn't the UM46 support baked in LUTs? I thought it did. In fact, I specifically asked a BM rep this exact question at NAB last year and I was told it did.

    EDIT: to be more specific, I was told the new 4.0 OS would support baked in LUTs, which wasn't out at the time.
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  10. #20  
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    Quote Originally Posted by nyccomposer View Post
    I agree, all but news and a few outliers maybe will want LOG footage anyway.

    I wonder, does the new firmware allow you to record with a user LUT, or only display the result of it on the screen?
    No it's display only at the moment. I have a feeling it's not easily possible to bake it in as the LUT's don't have the same precision.

    It would be great if they could though. That's the easy solution.

    JB
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