Is Canon Log useful for still photography, or only for video?
Asked 4/15/2012
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Canon Log uses a logarithmic gamma curve to preserve highlight and shadow detail for grading later. Canon says it can capture up to 12 stops of dynamic range, which sounds appealing for stills as well as video. If I shoot still photos, does Canon Log actually improve dynamic range or low-light performance compared with shooting RAW, or is it mainly a video feature?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
14y ago
2 Answers
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"Gamma" simply refers to the shape of the curve that maps sensor readings into image brightness numbers. A linear curve simply scales the sensor values, a logarithmic gamma curve means more values are attributed to the shadow region, preventing a loss of detail and increasing the dynamic range you can exploit in post production.
If you shoot raw you're capturing 14bits of luminance data from the sensor and you can apply whatever gamma correction you like during the raw conversion so you don't gain anything from a nonlinear tonecurve.
Dynamic range is the difference between the saturation point and the point where detail is lost to noise in the shadows. By carefully choosing the definition of acceptable detail manufactures can massage almost any DR figure they want out of the data! Canon saying "12 stops" is meaningless without knowing what threshold they've set for when noise overcomes detail.
Originally by user1375. Source · Licensed CC BY-SA 4.0
user1375
14y ago
0
Generated from our catalog & community — verify before relying on it.
For still photography, Canon Log generally does not give you an advantage over RAW.
Canon Log is a gamma curve: it remaps recorded brightness values so more tonal values are devoted to shadows and highlights, which is useful for video grading. But if you shoot RAW stills, the camera is already recording the sensor data with high bit depth, and you can apply whatever tone curve or gamma you want later in RAW processing.
So Canon Log doesn’t increase the sensor’s true dynamic range for stills. It mainly changes how tonal values are encoded in a processed image/video file. Any claim like “12 stops” also depends on how the manufacturer defines usable shadow detail, so such numbers are not always directly comparable.
In short: for stills, shoot RAW if you want maximum flexibility. Canon Log is mainly beneficial for video workflows, not for improving still-photo dynamic range beyond what RAW already captures.
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