Colorimetric and Resolution requirements of cameras
Alan Roberts
ADDENDUM 70 : tests and settings on a Canon EOS C300
Tests were made on a pre-production sample of the Canon EOS C300. Clearly, the specification and performance of the camera may differ when it is released, and therefore any details and measurements in this document are subject to modification, when a production model is tested. Canon have made it clear that this is only their first offering of a ‘digital-cinema’ camera.
The camera has one large CMOS sensor (super 35 size, 24.6×13.8mm) and uses interchangeable lenses. It will be available with one of two lens mounts, the standard PL, and Canon’s EF range. EF lenses can be controlled from within the camera, while the PL mount has no electrical connections to the lens.
It records MPEG2-compressed video, and has HDMI and HDSDI output, but all the tests were made using the recorded MPEG2 signals, and analysed in software. It has a built-in monocular viewfinder, and connection ports for external LCD panel, control handle and other accessories.
The sensor is a single CMOS, total 4206×2340 photo-sites, of which a central patch of 3840×2160 is used for the video signal (the implications of this will be discussed in detail in the measurements section).. Recording is onto Compact Flash card (two slots) in MPEG-2, long-GoP, with MXF file format. Three bit rate options are available: 50Mb/s CBR (constant bit rate) at 4:2:2 colour sampling (1920×1080 or 1280×720), 35Mb/s 4:2:0 VBR (1920×1080 or 1280×720) and 25Mb/s 4:2:0 CBR (1440×1080 only). Thus it complies with broadcast requirements for bit rate and offers more economic rates for greater economy (the 25Mb/s option matches HDV format). At these rates, a 64GB card can record 160, 225 and 310 minutes respectively. In 1080 mode, both interlaced and progressive modes are available. Off-speed recording at fixed speeds from 12 to 60fps is possible. Recorded content is to 8-bit depth1; this is a limitation of the internal processing. HDSDI and HDMI outputs are also both 8-bit depth, although the data-stream is 10-bit. This does not appear to have any detrimental effect on the camera performance.
There is a conventional rear-mounted monocular viewfinder (specification 1.555Mpixels, about 1662×935 pixels). A larger accessory viewfinder (included in the kit) can be top-mounted on the camera, and adds significant extra controls to the camera. There is also an accessory side-mounted handle with record button. A WiFi dongle can be added, so that the entire camera can be monitored and controlled remotely from a laptop or suitable mobile telephone.
There are neutral filters for exposure control, and manual control of the lens. Sensitivity is good, and noise levels low. On-screen video level monitoring is good, there are options for both waveform monitoring and vectorscope. There is an image magnifier as a focus aid.
Connectivity is good, with HDSDI, HDMI and timecode, analogue HD luma signal or SD composite via BNC socket, and XLRs for audio via the accessory viewfinder module. Headphone and stereo microphones can both be connected via 3.5 mm jack sockets, independent of the viewfinder.
Power consumption is about 10.5 watts at 7.2 volts, rising to about 11.5 watts with the accessory viewfinder. There are 15 assignable (user) buttons. The bare camera weighs 1.43kg, which is fairly light for a large format camera, although this figure can double when the camera is fully equipped with accessories.
The camera performed well under test.
CONTINUED…/
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