litote wrote:... Could you explain a little about what you mean by: “If you are shooting ProRes, you want to expose for the scene.”?
When you use a faster aperture (or minimal ND filtration) you let in more light. On a histogram, you’ll typically see the scene shift to the right. The zebras are a hint you may have let in too much light and are clipping. If you use the histogram you can judge clipping by seeing a white vertical bar at the right. You usually don’t want that so you may add a stop of ND or close down the aperture a stop, but most of your scene is on the right of the scale. Often raw is shot ETTR and you pull down the exposure in post as appropriate.
But ProRes is not quite as flexible as raw and so you often expose ProRes so that there’s a good balance in the histogram, not too far left or right. The histogram doesn’t tell you where your skin tones are though and that’s where false colour is so helpful. You can have the histogram indicate your scene is mostly to to the left, but if the false colour shows you have skin tones around green to pink, you know you may have a safe exposure for ProRes. So you’re not shooting ETTR or ETTL, but shooting for the scene where the skin tones fall in the colour you want them to be in that particular scene. Scene 1 you may want skin green and scene 2 you may want skin pink or even light grey. You’ll quickly get used to judging what you want when you expose for the scene.
BTW, when photographers talk about stopping “up” or “down”, regarding apertures, I am confused. Does “up” one stop refer to increasing the aperture, or decreasing the aperture diameter by one f-stop?
Well I hope my explanation Is correct: technically to be more precise, aperture refers to the ratio of the focal length and the opening of the iris or diaphragm so that a 50mm lens with a 25mm maximum opening for the path of light is an f/2 lens. That’s the simple approach used in photography lenses. Cinema lenses Mark their f-stops by measuring the amount of light that is transmitted and hence are more accurate when determining and exposure. That f/2 lens becomes a T2.1 lens allowing for the reflection and absorption of light in the lens, not the simple math.
You open up the iris to use a larger opening for the path of light and a fast aperture like T1.5 and you close down a stop or two to use a smaller opening and a slower aperture like T2.8 or T4. T4 is a one stop smaller aperture than T2.8.
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