Exposure methods for Shooting RAW. Pictures Styles, Hist.....

[Nachelsoul]

Hi all. I am wondering what are the acurate method to exposure RAW, what is the preferd PS to get the right exposure? and what tools we have in Magic Lantern to help that task. I have read various post about ETTR and other features but I don't catch the way to procedure. Thanks for the answers

[hirethestache]

From a cinematographers perspective, you should be able to dial in your shot in regards to exposure and temperature without even looking at "the monitor". ML 2.3 has a very good waveform monitor in the overlay menu, and this is where you start with exposure. A waveform is very similar to a histogram in appearance, but is not read the same.

A histogram seperates the total image into three basic categories from left to right(horizontal): low, mid, high. Generally speaking, a waveform monitor displays light value from 100%(crushed blacks) to 0%(clipped whites), and is vertical. If color correction/grading is in your planned workflow, you want to stay away from 100% and 0%, especially if you're shooting with a compressed format such as h264. With shooting compressed, your darkest of blacks should be 75% and your brightest of whites should be 12.5%. You have much more flexibility with raw, and you have freedom to completely crush your blacks(110%+) and clip the whites (-10%-).

My favorite feature with using a waveform is that while your luminosity value is shown on a vertical scale, your luminosity waveform is a representation of your image & displays horizontally, allowing you to see where the light is and what it is doing. Here's two simple visuals I mocked up for you to kind of define what I mean:




This is a basic staircase-like gradient. You can see how the values rise like a staircase on the WFM from left to right, because that is how the light is dispersed in the image.

Here's something a little more realistic, at least in terms of light:


You can see how the WFM levels are subjugated depending on the intensity of the light.

And this, my good sir, is how I recommend you expose

[Nachelsoul]

Invaluable class. Thank you so MUCH. I´ve digging around and it is the best explanation I´ve read. Great graphics. Sure my next shoots will be better.
But I have notice that when you change the PS´s, the Histo and Waveform change also. My principal concern is to know what PS or metering should be the closest to what the sensor recieves. ALso notice that images in ACR doesn't have the same levels they were shoot.
Sorry if I am saying stupids things. Pardom my english.

[a1ex]

Waveform is computed from jpeg YUV only. For raw video and photos, use raw histogram, raw zebras and maybe auto ETTR.

[hirethestache]

Think of it this way:

In regards to light/color, when shooting a raw .C2R IMAGE, your picture style is not baked into the file. On the other side of the spectrum, when you shoot a .JPEG IMAGE, and you're on for example monochrome PS, then your final image will retain that black and white spectrum. Likewise, if you were to crank the contrast all the way up and the saturation all the way up on a RAW image, the effects will have no impact. But on a jpeg, you will end up with a...umm...beeeeautiful file to work with *cough cough*

Convert this to video. If you're shooting raw (comparable to .c2r in photo mode), then picture style will not effect the final output. If you're shooting h264(comparable to jpeg), then search for Technicolor Cinestyle. It is a superflat profile that will give your compressed footage a very "bland" image--and this is what you want.

[hirethestache]

Waveform is computed from jpeg YUV only. For raw video and photos, use raw histogram, raw zebras and maybe auto ETTR.

Didnt realize that, thanks for the heads up. Ive been using a smallHD monitor with WF/VS, not the GUI WFM.

OP: While what a1ex said is true about RAW video, you'd still want to use it for h264

[Nachelsoul]

Thanks both to give light in my darkness.