C100 - iso 850

[Kathy Smith]

Why is ISO 850 recommended when shooting in C-log?

[Eric Coughlin]

Because the image retains more dynamic range in the highlights. Below ISO 850 it retains more detail in the shadows, and above 850 the dynamic range remains the same, but you're adding noise. Here is a chart which shows the dynamic range at various ISOs.




My few questions on the matter are...

So then if one wanted to film a night/dark scene, wouldn't you want more details in the shadows, such that you'd want an ISO below 850?

Does ISO 850 being the ideal ISO only apply to Canon Log or to all picture profiles? I was under the impression it applied to all picture profiles.

With Canon DSLRs, there was said to be various native ISOs, which the majority of people seemed to agree to be multiples of 160, and to therefore avoid the other ISO values which had more noise. Is there a similar method to the ISOs on the C100?

[Pavel Sedlak]

There are some players who have come into play:
- like dynamic range, noise or signal to noise ratio, 12bit or 10bit quantization analog to digital converter, quality of the glass, postproduction, etc.

The main problem is to maintain the quality of the entire manufacturing process, from glass quality to postproduction. Most people do not understand to this concept of quality and separate one parameter from the context, which is not correct.

The quality of the result begins with thoughtful and imaginative way of shooting then follows the concept of technical quality (optics, quantization and gamma, recording quality). If you have only 10bit quantization ADc and you have the camera chip with 4000 levels (linear 4000:1 or 72dB of the dynamic range), you have problem becouse 10bit gets only 1024 levels - it is one point of view (for this quality you need better camera with better 12bit SignalProcesor).

If you have better SignalProcesor you need a better glass and better record (10bit 422 with 180-220Mbps), this continues through the next processing.

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So I personally think that with C100 (10bit ADc and DSP and 8bit AVCHD) it is not so crucial if you use iso320 or 850 with Canon-log because you have no chance to exploit the full potential of 4000 levels from canon-log curve. But you have a very good chance to make a very good footages if you are imaginative. C100 is the middle class camera where really depends on the creativity of operator. The correct exposure on the 18pct middle gray (on canon-log curve) or small pulling exposure with -6dB gain (320 ISO) can't disturb your game, try this on the same scene and you will see .-) .