Love it or loath it it's something anyone involved in generating 'film' images is going to have to get to grips with some time or other - if they don't retire first

The problem is that there are a bewildering array of digital cameras out there, as well as a vast range of digital formats. And not all come close to being capable of being described as Digital Cinematography cameras - but that's not to say they don't have their uses, just that you need to understand their limitations if you are going to get the best out of them

As this website evolves I will be adding information on a range of Digital Cameras, with a focus on true Digital Cinematography.

And along with the camera itself are discussions on workflows, LUTs, data management, on-line editing, grading and Digital Intermediate.

But the one big issue to remember is that shooting for a theatrical product is not the same as shooting for TV... Get that right and most problems will vanish.

The Digital Revolution
The on-going digital revolution in film making brings the mixed blessings of greater variety of production choices than ever before, combined with the need for a greater level of knowledge if things are to go smoothly...

But does Digital Cinematography actually exist?

Promises, promises
Digital Cinematography is something that has been on the cards for years, with many camera manufacturers claiming Digital Cinematography capabilities way before now - and often without any serious 'cinematography' capabilities. Hands up all those who remember Sony's Digital Cinematography claims for DigiBeta! I think I've even got their VHS marketing tape somewhere at home - if I remember rightly, snappily titled 'Digital Cinematography'.

HD makes the right noises
However, the introduction of HD brought with it cameras that were capable of being considered close to, if not truly capable of being called, 'digital cinematography' cameras.

But, the issue initially faced by these cameras was a WYSIWYG approach to image capture, as has been historically the case with all 'video' cameras. The latitude of the captured image being designed for immediate transmission, rather than for later creative post-production, as has been the case with film captured images since its introduction, some 100 years ago.

Becoming more 'filmic'
The first approach to making these new HD cameras closer to true digital cinematography was to add 'film' profiles to their settings, to give a more filmic image.

However, the first 'film' settings applied by the manufacturers mistakenly attempted to match print film characteristics, rather than film negative; a result of the historic approach by digital camera manufacturers to make the captured image immediately usable.

While based out of Rome's Cinecittà Studios I was lucky (unlucky?) enough to have access to one of the very first Panasonic VariCam cameras with 'cine mode' settings, and was very disappointed with their attempt to emulate print film characteristics.

Sony then followed with their Gamma Curves, with a selection of downloadable settings that also emulated film print stocks.

How could manufacturers get it so wrong? Print stocks are not used to capture images!

Luckily, Sony also introduced a software program that allowed for user manipulation of the camera settings, and Digital Praxis generated a selection of CVP Gamma Curves that matched closely the high dynamic range, low contrast capture techniques of camera negative film, generating a near Log output image (as is the case with camera negative film).

These curves have become something of an industry standard for DoPs using Sony CineAlta cameras.

Manufacturers follow...
In recent times both Panasonic and Sony have introduced modes or settings of their own capable of mimicking the above approach to image capture, and Thomson went one step further with their Viper camera and its Log based FilmStream mode.

Cameras getting ever closer to true digital cinematography capabilities!

Depth-of-Field
However, an outstanding issue for many users of these cameras is the their depth of field, with HD cameras having 2/3" CCD sensors, so having a deeper depth of field than 35mm film (akin to 16mm film). For many this means the digital images are still too 'video-esk' when compared to 35mm film's shallower depth of field.

But, over the past year the digital cinematography market place has grown significantly, with a number of new cameras being introduced that really can be considered as being Digital Cinematography rather than re-purposed HD video.

High latitude, high dynamic range, low contrast capture has become comparatively commonplace, and some cameras are now using full 35mm aperture sensors, answering the final question to enable true Digital Cinematography.

Capture Resolutions

Resolutions have also increased, with new data cameras with 2K and 4K resolutions coming to market. The Red One, and Dalsa's Origin, now in version 2 form, being examples of 35mm sensor based data cameras, and Silicon Imaging's SI being a HD sized sensor camera, but with 2K capture capabilities.

More than one option
This means that today we have two main development strands that contain cameras that could be considered as being digital cinematography capable.

2/3" HD sensor based cameras with extended dynamic range capture capabilities; and data cameras with extended dynamic range, some with 35mm sized sensors.

And in between there is the Arri D20 and Panavision's Genesis, which output a HD image signal (and resolution), but have 35mm sized sensors.

In the HD camp, the cameras output/record via a HD video stream at 1920x1080 or 1280x720 resolutions, usually to in-camera tape decks, or external tape recorders, depending on the output format - single link HD or dual link - although they can record to data recorders too if required.

Cameras in this camp include Sony's initial CineAlta range, including f900, f900R, and Panasonic's VariCam.

The HD format and recording technique defines the final image quality, with single link being YUV (YCrCb) 4:2:2, with in-camera recording for Sony's CineAlta cameras at 1920x1080 resolution actually being recorded 1440x1080 through pixel reduction, with reduced bit depth from 10 bits to 8 bits, chroma reduction, plus additional DCT based compression. The result is that there is a limit to the amount of dynamic range that can be captured without the introduction of artefacts and/or banding becoming visible.

Panasonic's VariCam starts at 1280x720 and applies a similar level of pixel and bit depth compression when recording, although no colour reduction. As a result the final recorded image quality is very similar to that of the Sony HDcam camera range, but with added benefit of variable frame rates.

Cameras that record only to external tape decks, specifically Sony's HDcam SR format, can record 4:4:4 RGB with minimal compression, much like the following data based cameras. The limitation is the format’s HD resolution of 1920x1080.

Cameras that are within this camp include Sony's f950 and their new f23, Thomson's Viper, Panavision's Genesis, and Arri's D20. The difference being Sony and Thomson's use of 2/3" HD sensors, and Panavision and Arri using 35mm sized ones.

Sony are making a lot of their new f23 (based on the HDC1500), and it is a very interesting camera with good dynamic range and very clean images, but still 2/3" sensor based. I think this is going to be its biggest weakness.

Data cameras, as would be expected, record to data recorders, some with compression, some without, although this tends to be a user option depending on shooting techniques and the data format and recorder in use.

True data cameras are only just coming to market, combined with a range of data recorders, although data recording has been in use for some time with some HD based cameras, notably Thomson's Viper as it has no associated HD tape recorder.

As an aside, the first feature film to be shot 100% via a data workflow, and posted the same way was Silence Becomes You, with which I was heavily involved, and which used Viper and the S.two data recorder.

Cameras in the true data camp include Dalsa's Origin, Red's Red One, and Silicon Imaging's SI-2K camera.

Of these cameras I think it's fair to say the Dalsa has shown the most stunning images, capturing 4K data via uncompressed data recorders, notably the rather large Codex recorder, but with a smaller version on the way.

The SI-2K and Red show an interesting workflow methodology, both using wavelet based compression to get their high data capture rates down to manageable bandwidth levels. 4K capture in the case of Red, and 2K for SI-2K, obviously!

Compare and contrast
Over recent months comparative tests have been performed by Axis Films at Shepperton Studios, and by members of Geoff Boyle's Cinematography Mailing List (CML) to attempt to compare the various cameras by comparing the available dynamic range of as many of the newer HD/digital cinematography cameras as possible, as well as several Super 16 film stocks.

Of immediate interest was that while all the cameras were rated to have the same mid-exposure, in practice, none were exactly identical, which can cause problems when attempting to rate a camera for shooting under different lighting conditions. The rating of film stock is well documented and well understood.

Other interesting results included the Arri D20, which Arri would not allow us to test in LOG mode. The reason for this is probably that previous tests show it to have very poor shadow detail rendition, with excessive noise when exposure levels fall too low. Keeping the camera in LIN mode seems to mask these issues as shadow detail is effectively cut off.

From a post-production perspective, the Viper FilmStream and Sony f23 came out on top, with the best overall latitude allowing for great flexibility in post, and limited crushing of shadow detail or clipping of highlights.

The D20 was very clean, but ran out of shadow detail so quickly as to severely limit latitude, and hence later post-production grading options.

The f900R with Digital Praxis Gamma Curve looked much like previous F900/3’s, although cleaner. The F950 seemed to match the f900R, which makes sense as its output was limited to the same data levels as the single link f900R, and Sony have still not commented on this problem.

A good surprise was how well the VariCam in film record mode seemed to cope with over and under exposures.

These tests were very technical and don't always tell the real story when shooting in real-life conditions with shadows, bright areas and highlights contained within the image at any one given time.

Personally a simple, and I think preferable, way of testing latitude is to take a high dynamic range image, view it through a print LUT, grade it for nominal exposure and then see how much detail is clearly visible within the shadows and highlights through varying the grade. This tells a lot about the capabilities of a given camera.

Reported issues
During testing, and during actual use, there have been a number of issues reported with digital cameras, with some showing highlight artefacts, such as ringing around bright areas of the image; some showing smearing, again most notable around highlights; others having excessively noisy shadow detail; some showing compression or other 'digital' artefacts within the image.

But then film's not a perfect capture medium either...

Understanding the options
When choosing the camera for a specific project it's not just the camera that is important - the workflow required to get from scene-to-screen is equally important, if not more so.

In-camera tape recording is a very simple workflow, but has potential quality issues as mentioned above.

External tape recording will improve quality, but with the need to be tethered to the external recorder.

Uncompressed data recording also required tethering to the external recorder, but offers the best potential quality.

Compressed data recording is a new addition to the capture workflow, and as the two main systems being introduced use wavelet compression across the entire frame the quality potential is greater than in-camera tape systems using block based compression.

The camera choice tends to be based on the look required, including depth of field and single Bayer chip vs. three chip sensors, as well as the desired resolution.

Resolution as a requirement
One of the big discussion points, and something I've deliberately left until last, is resolution.

I've left it until last as resolution is nowhere as important as dynamic range and depth of field when it comes to making images that can be truthfully call Digital Cinematography.

With 4K cameras already being available in the form of Dalsa and Red, discussion on higher resolutions is really a moot subject. The human eye just can't see such resolutions, and using the eyes resolving limit of 1.7 arc minute even viewing images on the largest theatre screen sizes produces a theatrical max resolution of approx. 2K, which is damn close to HD...

Next up?
Axis Films and the CML will be getting together in the near future to run a series of 'real life tests', where scenes will be set up to test the cameras when shooting wide dynamic range scenes within a single frame and grading the captured images to explore the true final dynamic range, as well as comparing resolution and depth of field - and anything else that comes to mind :o) Stay tuned, and see the results at www.cinematography.net, or book a visit to Axis Films at Shepperton Studios.