If not Canon Log, then what?
OK, so with the Canon 1Dx mkII, Canon Log is out the window and we have to find what the best alternative picture profile is.
Plenty of Canon users have been shooting for years with the so called “Prolost” settings, myself included. Although, at the time I didn’t use that name.Prolost.com
is the blog by all-around-nice-guy Stu Maschwitz. Stu has been living in and around the film industry for a long time—he worked at Industrial Light and Magic at one point.
When the Canon 5D mkII was released many of us jumped at the camera: full HD video recording on a 36x24mm sensor! Unheard of. The image had aliasing and the codec was seriously compressed 8bit, h.264, but that didn’t matter. To get the most out of the images then, we turned down the contrast of our favourite picture profile all the way down and reduced in camera sharpness too. It was recommended to also reduce saturation by one or two steps. Stu blogged about this and gave name ‘Prolost Flat’ to the following settings: Sharpness all the way to the left, contrast all the way to the left and saturation to -2. I was using similar settings myself, but with saturation at -1.
Now, it’s much easier to refer to the “Prolost settings” than to start specifying where each setting for contrast and so on has to go. That is why I now offer you—tongue firmly in cheek—my Pixla HTP settings
The Pixla HTP settings
The Pixla HTP settings build upon what we already know, the Prolost Flat settings, but make use of an additional tool in Canon cameras: Highlight Tone Priority
Highlight Tone Priority, HTP going forward, has been in Canon cameras for a long time. I remember it being marketed towards wedding photographers, offering them assistance to not blow out white wedding dresses when shooting .jpg. It doesn’t do anything to the image data when shooting raw, so it’s often dismissed by serious photographers—but it has its use for video. Here’s how it works:
When activating HTP the camera will pull the exposure by one stop (under exposing it) and then boost the low and midrange back up when compressing the image data, leaving the top highlights alone thereby giving you one stop extra protection. Since the camera needs to pull the exposure internally, the lowest available ISO becomes 200 with HTP enabled.
Incidentally, this is very similar to how Canon Log works in the 1Dc. Canon Log stipulates the use of ISO 400 or above so that if can if fact pull the exposure by two stops internally
. Setting the Canon 1Dc to Canon Log and exposing at ISO 100 or 200 (it’s still possible—not locked off like ISO 100 with HTP) there is no way to hit IRE100, regardless of how much we over expose: the exposure has been pulled down.
Without this trickery, it would be very difficult to get to the 12 stops of dynamic range that Canon Log offers, since the image sensor in the 1Dx and 1Dx performs just shy of 12 stops in raw. OK, so Canon Log recovers 2 stops and HTP can recover 1 stop.
Now, if this was all it took, we would already be halfway there to Canon Log! Unfortunately, that’s not quite the case. Canon Log uses its own gamma curve and offers a much softer roll-off into the highlights. When setting the camera to HTP mode, only the very top highlights get recovered. Much of the images still follows close the REC 709 curve.
Well… to my eye, Canon Log has a much more filmic light distribution. Even if you set the blacks in post close to zero, the contrast is much lower in the lows and mids than Pixla HTP. That is why I always use it when I shoot. That said, there are situations where you would benefit from a steeper curve initially, so that it takes less light (a smaller Exposure Value—EV) to work yourself up the IRE ladder.
Let’s do a series of tests under various lighting conditions to see the impact it would make, if all we could use was Pixla HTP.
To be continued…