Liam Hall
Veteran
I have a theory Sony work out these numbers based on a 300 degree shutter.
FS7: Overexposing on the FS7 for cleaner shadows
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I have a theory Sony work out these numbers based on a 300 degree shutter.
morgan_moore
Major Contributor
Shutter off that's what it says - meaning 300 at least if not 360.. Although I'm not sure you can do true 360 with rolling shutter
BarryLichtner
Active member
Reading Aharon's post and the following replies sent me down quite a rabbit hole wrt how the Sensor in the FS7 is calibrated for temperature (for which I could find no answer), and then into color theory, which eventually swallowed me whole.
It'd be interesting to know if the sensor in the FS7 has a lower s/n ratio for accurate color at a given color temperature.
All things equal, I really prefer the look of almost anything "natural" in an accurate 3200K light, vs an accurate 5600K light. I think I actually have a harder time judging whether colors are accurate at higher temperatures than lower temps.
It'd be interesting to know if the sensor in the FS7 has a lower s/n ratio for accurate color at a given color temperature.
All things equal, I really prefer the look of almost anything "natural" in an accurate 3200K light, vs an accurate 5600K light. I think I actually have a harder time judging whether colors are accurate at higher temperatures than lower temps.
JPNola
Veteran
True that most of the time there is something white in the shot or just outside the frame that you can use for setting exposure IF that white is under the EXACT same light level as the face of your subject. That isn't so common. Rare are the instances where there is any pure white in the frame or just outside of the frame that is also in the same light level as your subject.
Your subject has on white slacks. White slacks that are pure white. Official Institute of Radio Engineers true white slacks that are brand new, just out of the box. But the lower body of the subject is in less light than is the face. So the white pants are of no use as an exposure reference for the subject's face.
"Exposing by looking at zebras on a face is wrong and it always will be wrong. Obviously the overall intention is to have the face look good, but you get there by exposing for white, not by exposing for the face itself. Is it really that hard of a concept for people?"
It isn't a difficult concept at all. I get your point about the human face being an imperfect reference point for setting exposure since human faces come in all different shades ( varying degrees of luminance ). But so does "white". That is, what appears pure white to the human eye may not actually be pure white. A quality white card in good condition is pure white, but "white things" in the frame or just outside the frame, not always so much. Thus I take issue with the statement "Anything white will do". And, arguably, using white as a reference is also "wrong" unless that white is true, pure white which is in the exact same light level as the face of the subject.
Seeing as there is rarely anything of true, pure white in the frame or just outside of the frame and also in the identical light level as the face of my interview subject, I expose for the face of the interview subject using the face of the interview subject. Makes sense, no? Set exposure for the thing for which you are most concerned about using the thing you are most concerned about. Admittedly, it is a method that is inexact science. But that is where experience comes in. Besides, I can't be pausing an interview to place a white card next to the subject's face every time the light level changes with changes in the level of natural light. Or every time a walking subject moves through different light levels.
When you shoot under natural light, Doug, all of the science of the white card goes out of the window as soon as the level of natural light changes. If one is using true white to set exposure and there is nothing in the frame that is true white and also under the same level of light as your subject's face you have nothing by which to adjust exposure in accordance with the changing light level. You are going to have to guesstimate every bit as much as using the subject's skin tone ( estimated luminance ) to set exposure. Whereas, on the other hand, if setting exposure using zebra on the subject's face you can ride the exposure with the changing light level and more keep the exposure of the face at a constant. You simply ride the iris so that the zebras on the face are consistent. Your reference, the face of the subject, is always there in frame and available to be your reference.
I prefer having a constant exposure reference on the face of the subject. Were I to set exposure by pure white I would not be guaranteed an ever-present reference. The zebra would not indicate increasing exposure on the subject's face until the level on the face hit 100%. And by then it is too late. With zebra set to something like 70%, I see the amount of zebra incrementally increasing as the light level hitting the face increases. And I can respond accordingly.
I think, or at least I hope, I have successfully made the case that using the face to set exposure- something labeled as being "WRONG" - has advantages over using a pure white reference. There are often situations where as operator you are screwed if you are only using true white to set exposure. When setting exposure using the face of the subject you always have your reference available. And your reference is always 100% guaranteed to be in the exact same level of light as that for which you are exposing. Because your subject IS the reference.
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Doug Jensen
Carbonite Member
I strongly disagree with almost everything you have said in your last post, but it would take more time than I want to spend going through it line by line. Plus anything I say would just fall on deaf ears anyway. But I will say that I stand by every single word I have said on this thread already, and the challenges of using white as an exposure reference that you pose are not challenges at all in the real world. So if you've got a way of exposing that works for you, I suggest you use it.
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Liam Hall
Veteran
That's very easy to test, just need a light meter and a grey card. Shoot test card and take reading under both tungsten and daylight and see if they match on the WFM. I'd test that now but it's dark...
broughtonfilm
Well-known member
I also don't understand why people say that here as the shutter angle is of course taken into consideration when estimating native ISO. It is the same exact as saying "Oh, I think they estimated this ISO with a lens wide open and not stopped down" or something equally strange.
That's a good idea Liam, though I've always wondered about the corollary question - are light meters equally responsive under all color temp- presumably they should be designed that way.
I seem to recall they were not especially reliable with saturated colors and often they were more sensitive to very saturated blues. Buts that all a distant memory in my hazy brain.
Maybe if you tested say a daylight source , then filtered with an 85 filter and opened the lens 2/3 stop (or vice versa) that would be a safer test? In fact shooting a grey card in daylight and just placing an 85 filter over it then seeing if opening the iris 2/3 gave the same waveform reading might show something. Hmm... does that make sense or would you need to also change the cameras color balance? I confess my brain is getting a little hazy on this.
I seem to recall they were not especially reliable with saturated colors and often they were more sensitive to very saturated blues. Buts that all a distant memory in my hazy brain.
Maybe if you tested say a daylight source , then filtered with an 85 filter and opened the lens 2/3 stop (or vice versa) that would be a safer test? In fact shooting a grey card in daylight and just placing an 85 filter over it then seeing if opening the iris 2/3 gave the same waveform reading might show something. Hmm... does that make sense or would you need to also change the cameras color balance? I confess my brain is getting a little hazy on this.
broughtonfilm
Well-known member
What???! This thread is getting silly. The exposure is of course going to match. The question is what the camera's electronics need to do to achieve it, the whole claim was that it needs to apply gain to a specific color channel to keep the exposure the same which may cause increased noise (in example if its native response is 5500K, in order to be balanced for tungsten light it needs to boost blue channel's gain and this channel is usually more noisy in most cameras). This in turn affects our own estimation of what the ISO rating we are comfortable to work with would be per given color temperature. No, waveform will not give you this answer!
Liam Hall
Veteran
I was answering a specific point, about exposure and colour temp, and how to test it, but yes, you're right about the wider colour channel/noise point.
Liam Hall
Veteran
Again, no one was doing that. I was commenting on Sony's figure for minimum illumination.
broughtonfilm
Well-known member
So you stand by your suggestion that that would be the way to test it?
broughtonfilm
Well-known member
Got it. My bad, indeed I put words in your mouth, made wrong assumption because this was said in a context of native ISO. Your clarification makes sense. Apologies.