The Real Sensor Specifications for Current Cinema Camers vs. EOSHD’s Characterization

cmosis-CMV-12000

First of all, let me clarify. I’m not attacking Andrew Reid here – he’s done a good job of bringing a new sensor to our attention (the CMOSIS  CMV12000) that could potentially be used for a 4K S35 version of a camera like the Blackmagic Design Cinema Camera (and all the quotes in this post are from that linked article at EOSHD). However, there was one line in the article that was probably intended as a throwaway, but comes out as technically inaccurate on closer inspection, so I hope he doesn’t take it personally that I felt compelled to clear things up a bit. :)

The specs are certainly high end for digital cinema well into Red Dragon / Arri Alexa territory.

I think I understand the spirit of what Andrew is trying to say, but it’s only partially accurate in terms of the specifications. CMV12000 (which as Andrew mentions is intended more for scientific and industrial applications) actually competes more with Red Epic/Red Scarlet/Red One/Sony F55/Arri Alexa/C500 depending on what specs you are looking at and how you approach it. Both the Red Dragon and Sony F65 (to name two cameras) clearly exceed it in terms of dynamic range/resolution combinations. Let’s really compare it.

Note that since the CMV12000 is a sensor only and has not been implemented in a product yet, I will not be getting into certain details (like which cameras use onboard recording vs external recording, etc.)

Above is the CMV12000 scientific sensor by European company CMOSIS – it has amazing potential in a cinema camera.

  • Super 35mm / APS-C sized
  • 4K raw at 12bit (90fps) and 10bit (150fps)
  • 4:3 anamorphic 4,096 x 3,072

Let’s start with the resolution. As a brief primer, TV standard and digital cinema standard define resolution differently (in terms of vertical and horizontal pixels respectively) and I’ll be using the digital cinema approach here.

Max Horizontal Resolution

- BMCC: 2.4K
- Arri Alexa: 2.88K max horizontal resolution.
- Sony FS-700: 4K expandable with 1.92K at release.
- Sony F55: 4K max horizontal resolution (4096×2160).
- Canon C500: 4K max horizontal resolution (4096×2960 RAW max).
- CMV12000: 4K max horizontal resolution (4096×3072, higher vertical resolution than the Sony F55 and slightly higher than C500).
- Sony F65: Greater than 4K.*
- Red One/Red One MX: 4.5K max horizontal resolution.
- Red Scarlet: 5K max horizontal resolution (but 4K max horizontal resolution at 24/25/30P).
- Red Epic: 5K max horizontal resolution.
- Red Dragon: 6K max horizontal resolution.

*As for the Sony F65, I don’t want to get into that can of worms. With it’s 20MP sensor, let’s just say “easily 4K, probably more in the future” but not get too far into it other than to say that the current recording format is 4K.

As we can see, every Red camera outperforms the CMV12000 (in at least some way), not just the upcoming Red Dragon. Starting with the Red Epic, it outperforms the CMV12000 in terms of resolution in every way.

Andrew mentions another key marketing point in favor of the CMV12000.

Global shutter

Andrew is right to emphasize this. While neither rolling shutter nor global shutter is inherently superior overall, the oft-stated advantages of a global shutter over a rolling one relates to both both horizontal skewing of objects in motion (typically referred to as the rolling shutter percentage) and a decreased susceptibility to motion artifacts relating to camera vibration. Artifacts arising from these disadvantages on a rolling shutter are sometimes called “the jello effect”.

Out of all the cameras mentioned above, the only one implementing global shutter like the CMV12000 is the Sony F55, so that’s definitely a potential marketing point in favor the CM12000. Neither the Alexa nor Epic uses a global shutter (and I haven’t seen one mentioned for the Red Dragon yet but I don’t know one way or the other about it).

The frame rate at maximum resolution is a mammoth 150fps but that also needs huge power on the image processor side. At this frame rate bit depth drops to 10bit from 12bit. It goes to 90fps with the full colour gamut.

Let’s look at how that compares to other cameras. The list below is based on information retrieved today. Note that my list rounds NTSC specific framerates (such as 29.976 frames per second) off to the closest frame per second.

Max Framerates at 4K and Highest Resolution

- BMCC: Cannot do 4K. Max 30P 12-bit log at 2.5K.
- Arri Alexa: Cannot do 4K. Max 60P 12-bit log at 2.88K in 16×9 mode.
- Red One MX: 30P 12-bit at both 4.5K and 4K.
- Canon C500: 60P 10-bit at 4K.
- Sony FS-700: Upcoming 60P at unspecified RAW bit-depth in 4K.
- Sony F55: 60P 16-bit linear 4K.
- Sony F65: 120P 16-bit linear 4K.
- CMV12000: 90P 12-bit or 150P 10-bit at 4K.
- Red Scarlet: 30P 16-bit at 4K. 12P at 5K.
- Red Epic: 150P 16-bit at 4K. 120P 16-bit at 5K.
- Red Dragon: Unknown 4K (expected to meet or exceed Red Epic at all framerates but guaranteed 120P at 5K). At least 85P 16-bit at 6K.

There’s an on-chip HDR mode which works in a similar way to Red’s. This boosts dynamic range from 60db to 90db

60db is around 11 stops of dynamic range. 90db is over 15 stops (similar to the new Red Dragon sensor).

The HDR mode approach discussed operates by rapidly capturing two exposures consecutively at different shutter speeds to combine later for each frame. I’ve used this on the Red Scarlet and in my opinion under the right circumstances it can look quite good – especially when used with the right tools. But it can lead to artifacts that are not present when shooting using only the native dynamic range and is not something that everyone wants to use.

So let’s start by looking at the native dynamic range.

Native DR

- Sony FS-700: Untested in RAW.
- CMV12000: ca. 11 stops official (maybe a little more)
- Red One (not MX): 11.3 stops official.
- Canon C500: 12 stops official. (though the highlight roll-off has been garnering praise)
- BMCC: 13 stops official.
- Red MX (as used in MX/Scarlet/Epic): 13.5 official. (Some sources measured at under 12 but I’m not invested in one measurement over the other).
- Arri Alexa: 14 stops official.
- Sony F55: 14 stops official.
- Sony F65: 14 stops official.
- Red Dragon: Over 15 stops official.

So the CMV12000 has the lowest native dynamic range of any of the above current cinema cameras. Once again, it does have global shutter (and the only other camera on the list that has that is the F55) but the native dynamic range is around 2 stops lower than a ca. $3,000 BMCC.

In terms of extended dynamic range modes, the CMV12000 (over 15 stops), Red Epic and Red Scarlet (both 18 stops) all have them. The Red Dragon is also on track to feature one but with over 15 stops  native, as long as the Red Dragon implements any form of HDRX the Red Dragon will easily outperform the CMV12000 in their respective HDR modes without the slightest challenge. It would have to decrease in dynamic range not to.

So Andrew’s quote should more accurately read as “the HDR mode of the CMV12000 would allow it to approach the official native dynamic range of the Red Dragon” because currently it doesn’t give a correct idea of the respective performance of each (and completely ignores HDRX on the Red Dragon).

The Arri Alexa has not implemented an HDR mode, so there’s no issue if you want to emphasize the CMV12000 HDR mode outperforming the native dynamic range on the Alexa. Of course, with both of them in native mode, the Alexa has a 3 stop advantage.

The CMV12000 has some great features on paper (anamorphic 4K and global shutter) but it is outperformed by the Red Epic in every specification (by varying amounts) other than global shutter. The Arri Alexa outperforms it in native dynamic range, but has a mechanical shutter option instead of global shutter and lower resolution. The same is true of the BMCC (except that it also has a smaller sensor and even lower resolution). The Sony F55 matches it in global shutter . And the Sony F65 and Red Dragon outperform it in every specification by a wide margin, except global shutter (with the F65 available with a mechanical shutter option instead).

In many ways, the CMV12000 would place a camera using it closer to a Red Scarlet or Sony FS-700 than the other cameras discussed. The advantages it has over these would higher potential frame-rates at 4K; the ability to shoot 4K anamorphic (without complications) and the global shutter.

So I hope you can see how the sensor Andrew mentioned (while having lots of great features) is not quite at the features level of the other cameras that Andrew mentions. However, it does have several great features and could potentially be useful in a higher frame rate or global shutter 4K camera at a lower price point. I’m glad he mentioned it – I just don’t think we should get carried away when in some ways it’s outperformed by the existing $3k camera that Andrew wants it to follow-up on.

Anyway, thanks Andrew, both for bringing this sensor to my attention (which I would have missed) and for (hopefully) having a good sense of humor about my post. I enjoy reading your blog frequently, even when I frequently disagree about technicalities like this. :)

4 Responses

  1. Jim says:

    Per,

    It’s pretty difficult to analyze the differences on sensor alone, but I think Andrew has a point. The CMOSIS chip, while only having 12 bit resolution can easily make up for it by:

    1. 90 FPS @ 4k 12 bit becomes 45 fps @ 24 bit resolution. In which hasit has excellent dynamic range at 24 – 30 fps. While 5k might be important to someone, it has to be at least 24p for it to practical.

    2. Both the gamma curve and the vertical sampling window on the CMOSIS chip can be modified on-the-fly yielding a very wide latitude of shooting parameters. This is from their data sheet.

    3. I think you’re significantly underestimating the value of global shutter. Considering the other specifications of the CMOSIS, global shutter makes this an incredible chip and if OEMs can release a camera based on it for a reasonable price, it could be a game changer. (Especially if the open source hardware projects amortize sunk development costs by releasing reference boards)

    Other than that, I do think it’s too early to get excited until we have prototypes in hand. Until then we buy GH2′s and rent the rest.

    Good summary BTW.

    Jim B

    • Per Lichtman says:

      Thanks for weighing in, Jim. I appreciate it when people add new information to the discussion.

      I’m curious to see what the real-world implementations of “1″ and “2″ end up being. At a competitive price-point it could be quite attractive. I was simply emphasizing how competitive the market is already, but few people anticipated the BMCC and it’s been well-received, setting the production delays aside.

      As far as the global shutter, I think it will really depend on the type of content being shot. If you’re mainly working in low-motion scenes (pastoral landscapes or relatively sedate talking heads, etc.) then it would be less important than if you are shooting tracking shots, Steadicam, helicopter shots or any sort of significant motion in the scene itself. So I think it will be important, but not necessarily to all shooters – there’s a significant number of people that favor using cuts as opposed to camera motion to maintain interest or don’t shoot a lot of motion in their scenes for other reasons.

      But sports, many forms of music videos, action scenes and reportage all stand to potentially benefit. I wish I had more time to look into the F55 to get a sense of things to come but I’ve been very busy with creative projects, so it will have to wait. :)

      All the best,
      Per

      • Those things are hard to judge by paper.

        I just tested a Scarlet @4k against a BMC @2.5k.
        I theory the Scarlet should be better, but in the real world, the BMC blew the Scarlet out of the water, regarding sharpness and actual resolution.

        That means, nominal you get 4k from the Scarlet, but there isn’t 4k worth of actual information in the image. Not even 2.5k information.

        Like you don’t get 4k of information when you take a 2k image into Photoshop and blow it up to 4k, thou is you count the pixels, its 4k nominal.

  2. Lee says:

    Hi chaps ! Hey Frank :) 4k post wise … my experience – the PM budgets on 1080 experience currently (of course) and is a nightmare – after finishing Muse multicam 4K for cinema and DVD – the hurdles were great and bloody (bloody!) expensive to overcome (hey it was Muse lol) As an example a director chum was trying to budget post for his upcoming 4k extravaganza and approached above post house on their success (hell) and he was almost 4x out with even the basic amount of cash to even make it.
    A very adept and experienced post house met many challenges along the way – monetarily ultimately was a shock for production i.e. it will cost 4x what you budgeted for – literally. Ingestion times of footage – length of ingestion – hiring 4k monitors etc – In the UK at least there’s a huge learning curve in budgeting, testing and delivering the VHS v’s Beta boys next new emperor.
    Aside from this production company tech guys take an age to ratify new cameras/format etc as I realised over a pint last week with my chum who oversees our Warner suites – 18 year old PD’s making TV can’t even use a camcorder yet lol – we’re a way off.
    Hey Ho – onward and upward!

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