It’s something I hear a lot of, that the AF100 is not as cinematic as the 5D. I think that’s putting it a wrong way, of course it’s cinematic in the right hands with the right optics – and cinematic is such a broad term. But there is something to be said for the feel of each camera, and they are very different beasts.
The way each is setup for colour, and the technical properties of each all contribute to what we see when we hit record.
14 bit
First the obvious – the 5D is unique because of it’s sensor size, but less obvious is that Canon DSLRs have 14bit analogue to digital (AD) converters on the sensor. I’m convinced this makes some difference to the image in video mode, although the image processor (DIGIC 4) only gives us the full 14bits in RAW stills mode and the effect is to flatten the image slightly and increase dynamic range.
The internal video codec in all DSLRs (and the AF100’s AVCHD mode) is 8bit which is only capable of storing 256 shades of grey. So all 16,384 shades of grey the 5D is capable of storing in RAW stills is chopped right down to 256 when recording to H.264.
The GH2 and AF100 have 12bit AD converters so they start with fewer shades to begin with (4,096). Needless to say behind all the science, the Canon DSLRs do seem to win out on colour.
Green Shift
Another contributing factor seems to be that Panasonic’s colour science seems to have bias toward green, which gives magneto tones a slightly greenish, yellowish tint. Here I selected the same shades in two frame grabs, one from the 5D Mk II and one from the GH1 (GH2 and AF100 have the same issues), important to note that both were set to the same white balance and had the same lens, under the same lighting conditions at the same time. The source image was of a sunset with nice velvety tones.
I am not sure what the technical reason is, be it something to do with the sensor or the implementation of white balance system – but if you dial the white balance in manually to the shot, the warmer you get the more green and yellow there is. I have not tried the AF100 directly yet but since they use a very very similar sensor and the same CPU with quite a lot of the image pipeline shared I expect the AF100 to be similar and the sample footage certainly does seem to not render warm tones and skin as well as the 5D Mark II.
I experienced this green-shift on both the GH1 and GH2 and although Panasonic have tried to fix it – the GH2 attempts to compensate with a warmer Canon-like image – it’s not quite as good as the real thing yet. Again, Canon seem to win on warmer tones.
Tungsten troubles
I also find it easier to get neutral white under energy saving tungsten indoor lights on the GH2. You know the effect – these awful lights give everything (especially fish & chips, for some reason) a green-ish tint, not the nice balanced white and warm golden yellows we get from daylight. The GH2 seems more susceptible to these common energy saving quibbles than the Canons, but it’s fine with proper studio lights and daylight.
The green channel of the image contributes a lot to resolution, and Panasonic’s sensors are certainly sharp – not just due to better video processing – in stills mode even the GH1 is sharper per-pixel with the same lens than the 5D Mark II. Panasonic once developed a sensor technology which doubled up the green channel and increased sensitivity and resolution (I believe it’s in their high end compacts), maybe they have it in the GH2 and AF100’s sensor too. They win hands down on the resolution battle, but a cinematic image is often thought of as being quite soft – so sharpness goes someway toward accentuating people’s view that the GH2 and AF100 are producing quite a ‘video-like’ image. Technically better but not aesthetically.
Summary
The AF100 and GH2 do have a technically better image – hardly any noticeable moire, less aliasing, excellent noise control – true 1080p not some awful soft 720p-esq stuff like on the Canons! On the negative side I believe there ARE small issues with colour, the compression in AVCHD is still too high and it is harder to get the same extreme shallow DOF which you can get on the 5D and even 60D – you need a very fast lens at quite a long focal length to mimic it. The GH2 and AF100 are weak for fast primes too, at the wide end you can get to 11mm F2.8 – it looks nothing like the shallow DOF cinematic look you get from a Canon 24mm F1.4L on a full frame sensor, it just isn’t as aesthetically nice and you couldn’t shoot something like Undercity on the AF100 and have it look identical to the 5D Mark II, purely because of sensor size and available optics.
I’ve been invited to an interesting test in Berlin with the guys at MBF and ReWo – a comparison of the RED ONE (MX), GH2, 5D, AF100 and Sony F3 – I’ll update my view around then!
All in all I’d caution against making a decision based on these rather petty scientific details. They’re both capable of dazzling images and I personally prefer the GH2 for most things.
What matters most is what you do with it.
