Thread: Dynamic Range... two different tests

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  1. #11  
    Join Date
    Apr 2012
    Sydney Australia
    Most manufactures calculate the DR as a theoretical number, based on the SNR of their sensor. They do this because it's a good way to objectively do it based on maths.

    All the other methods we argue about involve (rightfully) subjective judgements based on what is acceptable noise. Things like compression, in-camera pre-processing, internal bit depth processing also affect what this number can be. But you can't compare cameras from different brands that use different bit depths in this case other than what you photograph and compare.

    These numbers vary because of not only testing methodologies, but subjectively. I laugh when people compare DR on a still frame. The human vision perceives noise differently when it's in motion compared to a still frame. So why compare on a still frame when judging noise is the threshold for DR ?

    Arriflex have long understated the DR of their sensor by at least a stop, maybe more. It doesn't matter to me because it's usually "enough" for what I need to do. The best DR claims are the ones I can make for myself when I side by side to a known camera like the Alexa.

    In my experience the Ursa Mini is very very close to matching the Alexa for DR, whatever DR they claim.

    I even wrote about it here last time I checked it formally.

    Since I did this test, I've shot three TV series mixed with Alexa and I've not seen any shots that made me think any less of what I've found here.

    I feel so good about this camera and what it can do that I actually CHOSE to shoot Ursa Mini 4.6K over Alexa on the last show I did, "The Warriors".

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  2. #12  
    Quote Originally Posted by sammy View Post
    Arri lists the Alexa at 14.5 stops (we must agree on that to keep going with argument).
    That seems an odd way to proceed, to give more credence to a claim than to a real world test.
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  3. #13  
    Quote Originally Posted by Howie Roll View Post
    Cool test but the guy can't count.
    I noticed that as well. Shouldn't the proper count be between steps? So from 100 IRE to 90 IRE would be 1 stop, for example, where he was counting them as 2?
    Last edited by Jim Simon; 01-11-2017 at 02:55 PM.
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  4. #14  
    Senior Member
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    May 2012
    DXO gave RED Helium DR as 15.2 stop
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  5. #15  
    DR test of a single camera will always be subjective as hell. A sequence of methodological actions on the way to a semi-useless result. But If test made subsequently with other cameras there might be some benefit.
    Much more informative are tests made with a multiple cameras at the same time, with the results compared to each other. At least they give us immediate relative information, which is more useful.
    Though such tests will also be a bit subjective too, because there are too many camera unique variables, which are hard to take into account while counting the stops (noise type, sharpness, signal allocation, formats, etc...).

    Quote Originally Posted by DPStewart View Post
    I'm really sick of DR measurements of cameras that are not in a useful analytical context.

    There's probably 10,000 articles out there that say the DR of camera 'x' or camera 'y' is this, or that, or not what the maker claims.... But they don't immediately place "their" rating with other cameras upon which the EXACT same testing methodology was applied. It becomes useless information. And it spreads confusion and misconceptions. It gets to be information pollution.

    I'm reminded of Ken Rockwell's lens reviews. Many people like his style, and many people HATE his style, but one thing that's noteworthy is that his methodology is very consistent and that produces USEFUL information. I have shot with easily 20 lenses that Ken Rockwell has reviewed and his methodology is so consistent that I can tell if I am going to like a lens even if he DOESN'T like it because his baseline descriptions are standardized (even within his own personal vernacular) and I can know how to contextualize the information he is providing.

    In summary, I wish folks would do DR reviews of cameras with high levels of procedural integrity and standardization, or not do them at all.

    ....but everyone wants that advertizing revenue on their website...

    At least Tom Antos' analysis uses the exact same methodology across the board.
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  6. #16  
    Senior Member
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    Dec 2012
    Fairfield, CA
    Cinema5D is about as objective as it gets with dynamic range measurements, along with DxO. C5D uses a Xyla-21, Zeiss lens, and Imatest image profiling/calibration software to analyze and determine the dynamic range of the camera.

    They also measured the ALEV III at 14.5 EV.
    Eddie Barton

    My blog where I write about math stuff related to video:
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  7. #17  
    Quote Originally Posted by iaremrsir View Post
    Cinema5D is about as objective as it gets with dynamic range measurements, along with DxO. C5D uses a Xyla-21, Zeiss lens, and Imatest image profiling/calibration software to analyze and determine the dynamic range of the camera.

    They also measured the ALEV III at 14.5 EV.
    I agree they seem to have a good thing going. But something is either wrong with their UM4.6K or with the software, because on there test image of the Xyla chart there are 14 swatches visible, yet they say the FS7 has more dynamic range. Lots of people on the comments mentioned the crosshatching issue (which if one shoots raw and processes in resolve seems to not happen). It's not surprising that their software said 12 when 14 steps are visible, though that 14th is def a bit of a gravy stop – because their crosshatching is so bad. Yet they haven't redone the test despite it being pretty badly flawed.
    James Iain Barber
    Editor, writer, director, shooter, yadda yadda.
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