As I read it, it is sarcasm and a bit more :)
As I read it, it is sarcasm and a bit more :)
@bobn2 has written: @xpatUSA has written:It is fully supported by this article en.wikipedia.org/wiki/Exposure_value.
Apologies in advance if my sarcasm meter is not working properly.
As I read it, it is sarcasm and a bit more :)
@DonaldB has written:
Exposure doesn't include scene light. Exposure is shutter and t-stop. xpat has written:Excellent, Donald, I just now read your terse one-liner amongst all the obfuscation.
It is fully supported by this article en.wikipedia.org/wiki/Exposure_value.
Well done.
No sarcasm was intended. He said something right; I passed a complimert.
But, due to the classic Donald aggrieved response, my compliment is withdrawn.
@DonaldB has written: @JohnSheehyRev has written: @DonaldB has written: @ggbutcher has written:Current implementations use the JPEG EVF image, not much use for determining clipping with all the processing applied. I want blinkies based on the raw data.
have you actually tested your histogram accuracy ? because my sony a74 coudnt be any more accurate.
No one who knows what they're talking about has said that the in-camera histogram is not accurate for the camera's conversion or a default conversion. It is BASED on the camera's conversion parameters, so how could it be wrong for that purpose? What it doesn't show you is what is going on in the raw data, and depending on the camera and WB and ISO setting, the amount of raw headroom can vary tremendously. If you want to venture safely into those extended raw highlights, then you would want a raw histogram; not a default conversion histogram.
Wrong ,you need to actually test the cameras you think you know something about. then get back to me.
It's impossible for your camera to always give the same RGB headroom in both raw and display RGB, just because of white balance. Your camera would literally have to alter its filtration of color during exposure, or the raws would have to have WB applied to them (wasting headroom) for your assertion to be roughly accurate. Also, the only time you see headroom in the green channel approximately the same in the raw and display RGB is when the raws have limited headroom, like the "extended" ISO 50 in many FF cameras.
I just compared the Sony A7R2, Canon R5, and Nikon D850 at DxOMark, to see the saturation-based "measured" ISOs, and sure enough, the A7R2 has the least absolute highlight headroom at ISO 100. So, you may see the two histograms looking more similar with your camera than with the others, but that does not mean that your camera histogram is a substitute for a raw histogram, as the red and blue channel histograms will diverge due to WB. You'd have to have a white balance for a magenta light tint, and greyscale subject matter, to expect the two histograms to be as close, consistently. Add highly-saturated highlight colors and WB, and the two histograms will diverge.
Thanks John.
I have always enjoyed your unbiased posts towards members seeking technical information when compareing against practical experience.
i get a bit tired of the usual lets destroy Dons findinds by other members. its like some sort of game to them.
He said something right
He didn't, well not this time.
@xpatUSA has written:He said something right
He didn't, well not this time.
I don't why we have to do this, but:
He said "Exposure is shutter and t-stop."
Since "exposure" by itself means anything, is there some problem with interpreting it as Exposure Value (EV). If so, what is the problem? And it could be said that a photography can set any EV he likes, independently of the "scene light".
Now everybody except one here will go on about the "amount of light hitting the sensor" or quote CIPA or ISO's formula Hm = na-ni-na or words to that effect -but he makes a valid point albeit a vague one - deliberately so, perhaps.
Or, was "t-stop" bothersome, if so, why?
Being trite, if I go outside and twiddle stuff on my camera, the scene lighting does not change at all - it is independent of my twiddling.
@bobn2 has written: @xpatUSA has written:He said something right
He didn't, well not this time.
I don't why we have to do this, but:
He said "Exposure is shutter and t-stop."
Since "exposure" by itself means anything, is there some problem with interpreting it as Exposure Value (EV). If so, what is the problem? And it could be said that a photography can set any EV he likes, independently of the "scene light".
Now everybody except one here will go on about the "amount of light hitting the sensor" or quote CIPA or ISO's formula Hm = na-ni-na or words to that effect -but he makes a valid point albeit a vague one - deliberately so, perhaps.
Or, was "t-stop" bothersome, if so, why?
Being trite, if I go outside and twiddle stuff on my camera, the scene lighting does not change at all - it is independent of my twiddling.
Exposure value (EV) is a combination of a shutter speed and f-number, not t-stop. By mentioning t-stop he implicitly referred to the attenuation of the amount of light.
@bobn2 has written: @xpatUSA has written:He said something right
He didn't, well not this time.
I don't why we have to do this, but:
He said "Exposure is shutter and t-stop."
Since "exposure" by itself means anything, is there some problem with interpreting it as Exposure Value (EV). If so, what is the problem? And it could be said that a photography can set any EV he likes, independently of the "scene light".
Now everybody except one here will go on about the "amount of light hitting the sensor" or quote CIPA or ISO's formula Hm = na-ni-na or words to that effect -but he makes a valid point albeit a vague one - deliberately so, perhaps.
Or, was "t-stop" bothersome, if so, why?
Being trite, if I go outside and twiddle stuff on my camera, the scene lighting does not change at all - it is independent of my twiddling.
What Donald said was
Exposure doesn't include scene light. Exposure is shutter and t-stop.
Which is not totally correct technically.
Shutter speed and aperture are exposure settings , not exposure itself.
If you read on after what DonaldB posted above, you will see that he posted that the penny had finally dropped and that he now accepts that exposure is actually the amount of light that struck the sensor per unit area while the shutter was open.
@DonaldB has written: @DannoLeftForums has written: @DonaldB has written:Ok the penny has dropped. and i
conceiveconcede defeat . well sort ofconclusion: exposure = shutter, t stop, and scene luminance which is displayed by the histogram now we have practical picture (pun) to work off.
come on guys you have dropped the ball explaining the concept to the limited scientific minds. 😎
My fees are cheap if you want to quote my conclusion. 😁
I'm not sure but I think hell has just frozen over 😀
If I understand your concession correctly, does that mean you finally accept that exposure can be defined in layman's terms as the amount of light that struck the sensor per unit area while the shutter was open?
And that only
- scene luminance
- aperture
- shutter speed
affect the exposure as defined above?
Yes 😁😀😎
@bobn2 has written: @xpatUSA has written:He said something right
He didn't, well not this time.
I don't why we have to do this,
Well, given that 'exposure' is supposed to be one of the core concepts in photography, shouldn't we get it right.
He said "Exposure is shutter and t-stop."
which is wrong
Since "exposure" by itself means anything, is there some problem with interpreting it as Exposure Value (EV). If so, what is the problem? And it could be said that a photography can set any EV he likes, independently of the "scene light".
In the photographic vocabulary, 'exposure' by itself doesn't mean 'anything', it quite specifically means illuminance at the plane of focus times the exposure time. That's its well defined meaning and has been since the late 18th century. That's the meaning that is to be found in all the film data sheets, in the ISO specifications of photographic terms and in all texts written by competent authors. It's the root definition for everything else that depends on 'exposure'. If you get that wrong, you get everything wrong thereafter.
As for 'Exposure Value', its definition also depends on the definition of exposure, as it said in the Wikipedia page I linked. 'Exposure Value' is perhaps an unfortunate name, but it is the one we have.
Now everybody except one here will go on about the "amount of light hitting the sensor" or quote CIPA or ISO's formula Hm = na-ni-na or words to that effect -but he makes a valid point albeit a vague one - deliberately so, perhaps.
The point is this, 'exposure' is a jargon word, specific to photographic imaging in this context. It's not a word that lay people will use. Unless a photographer, they won't have much concept of how much light is hitting the sensor, and they won't refer to how light or dark a photo looks as 'exposure', and they certainly won't have a concept of the log2 version of f-number and exposure time. So, it's entirely within the photographic jargon. The point of jargon within fields is to aid precise communication within that field, we ascribe words exact meanings which operate within that field, which avoids ambiguity of discussion. Now if you're going to reintroduce all that ambiguity by playing fast and loose with those precise definitions, then what you're doing is corrupting the possibility of clear communication. You're best off not using the jargon at all. It's more accessible to people not within the field.
Or, was "t-stop" bothersome, if so, why?
T-stop is more precisely correct than f-number. 'In 'Exposure value' it is f-number by definition.
Being trite, if I go outside and twiddle stuff on my camera, the scene lighting does not change at all - it is independent of my twiddling.
That's right. But exposure changes because of the twiddling. And if you're in a studio with control over the scene lighting, you can twiddle that to change the exposure.
@xpatUSA has written: @bobn2 has written: @xpatUSA has written:He said something right
He didn't, well not this time.
I don't why we have to do this,
Well, given that 'exposure' is supposed to be one of the core concepts in photography, shouldn't we get it right.
@xpatUSA has written:He said "Exposure is shutter and t-stop."
which is wrong
Quoted message:Since "exposure" by itself means anything, is there some problem with interpreting it as Exposure Value (EV). If so, what is the problem? And it could be said that a photography can set any EV he likes, independently of the "scene light".
In the photographic vocabulary, 'exposure' by itself doesn't mean 'anything', it quite specifically means illuminance at the plane of focus times the exposure time. That's its well defined meaning and has been since the late 18th century. That's the meaning that is to be found in all the film data sheets, in the ISO specifications of photographic terms and in all texts written by competent authors. It's the root definition for everything else that depends on 'exposure'. If you get that wrong, you get everything wrong thereafter.
As for 'Exposure Value', its definition also depends on the definition of exposure, as it said in the Wikipedia page I linked. 'Exposure Value' is perhaps an unfortunate name, but it is the one we have. @xpatUSA has written:Now everybody except one here will go on about the "amount of light hitting the sensor" or quote CIPA or ISO's formula Hm = na-ni-na or words to that effect -but he makes a valid point albeit a vague one - deliberately so, perhaps.
The point is this, 'exposure' is a jargon word, specific to photographic imaging in this context. It's not a word that lay people will use. Unless a photographer, they won't have much concept of how much light is hitting the sensor, and they won't refer to how light or dark a photo looks as 'exposure', and they certainly won't have a concept of the log2 version of f-number and exposure time. So, it's entirely within the photographic jargon. The point of jargon within fields is to aid precise communication within that field, we ascribe words exact meanings which operate within that field, which avoids ambiguity of discussion. Now if you're going to reintroduce all that ambiguity by playing fast and loose with those precise definitions, then what you're doing is corrupting the possibility of clear communication. You're best off not using the jargon at all. It's more accessible to people not within the field.
Quoted message:Or, was "t-stop" bothersome, if so, why?
T-stop is more precisely correct than f-number. 'In 'Exposure value' it is f-number by definition.
@xpatUSA has written:Being trite, if I go outside and twiddle stuff on my camera, the scene lighting does not change at all - it is independent of my twiddling.
That's right. But exposure changes because of the twiddling. And if you're in a studio with control over the scene lighting, you can twiddle that to change the exposure.
A crushing response! I fold.
Donald was wrong ... again.
Pardon the added levity:
Two photographers at a swan pool ...
A: "What exposure are you using, mate?"
B: "Er, 1/60sec at f/11."
A: "Oh, I just pulled out my Gossen and it looks like that spot-metered swan is reflecting at 1200 candela per square metre so maybe 400 lux at the sensor and it's moving so I was thinking 1/250sec at ... ... ... oh, bugger, it's flown off!"
A crushing response! I fold.
Donald was wrong ... again.
Sorry, it wasn't supposed to be 'crushing', just thorough.
Don usually is wrong - doesn't stop him taking nice pictures though (except when it comes to motor sport).
Pardon the added levity:
Two photographers at a swan pool ...
A: "What exposure are you using, mate?"
B: "Er, 1/60sec at f/11."
A: "Oh, I just pulled out my Gossen and it looks like that spot-metered swan is reflecting at 1200 candela per square metre so maybe 400 lux at the sensor and it's moving so I was thinking 1/250sec at ... ... ... oh, bugger, it's flown off!"
There's a much quicker way of working out your exposure, if your meter is centred. Look at the ISO and the exposure for an 18% object will be 10/ISO lux seconds.
And you have to assume that Messrs. A and B are using the same ISO...
@ggbutcher has written:Thanks, and you're looking at the not-best rendition. Just looked at the raw histogram, all of the image except for the headlight is at or below 10%, "underexposed" by any account. It requires a fairly aggressive tone curve to put everything in a good place:
Taken in 2015, just learning to shoot raw, a lot of learning ahead to figure out what to care about. Still futzing with it; currently trying out the Z 6 highlight-weighted matrix metering with a +1EV exposure compensation. I think I'd rather shoot manual with freaking raw blinkies... 😆
Me too!
Opened in the GIMP, masked the lamp (not v. well), dialed it down a bit, applied contrast and brightness, three stages of USM, then "oilifield" ...
... the GIMP - don't leave home without it.
Pardon the typo.
I find your edit to have too much Contrast, with all the detail in the Shadows on the Train to be unseeable. But that is my Opinion
@xpatUSA has written: @ggbutcher has written:Thanks, and you're looking at the not-best rendition. Just looked at the raw histogram, all of the image except for the headlight is at or below 10%, "underexposed" by any account. It requires a fairly aggressive tone curve to put everything in a good place:
Taken in 2015, just learning to shoot raw, a lot of learning ahead to figure out what to care about. Still futzing with it; currently trying out the Z 6 highlight-weighted matrix metering with a +1EV exposure compensation. I think I'd rather shoot manual with freaking raw blinkies... 😆
Me too!
Opened in the GIMP, masked the lamp (not v. well), dialed it down a bit, applied contrast and brightness, three stages of USM, then "oilifield" ...
... the GIMP - don't leave home without it.
<unsatisfactory image deleted>
Pardon the typo.
I find your edit to have too much Contrast, with all the detail in the Shadows on the Train to be unseeable. But that is my Opinion
My edit was to demonstrate the power of the GIMP, not to impress anybody. Your image had too little contrast and all the detail in the Shadows on the Train was unseeable because I 'oilified' ther image.
I thought the main problem was the headlamp, not the aesthetic quality of my edit ... so, trying agian, only the lamp was changed in the original low-contrast image.
The black ring round the lamp is due to my quick and clumsy masking ...
@bobn2 has written: @xpatUSA has written: @bobn2 has written: @xpatUSA has written:He said something right
He didn't, well not this time.
I don't why we have to do this,
Well, given that 'exposure' is supposed to be one of the core concepts in photography, shouldn't we get it right.
@xpatUSA has written:He said "Exposure is shutter and t-stop."
which is wrong
Quoted message:Since "exposure" by itself means anything, is there some problem with interpreting it as Exposure Value (EV). If so, what is the problem? And it could be said that a photography can set any EV he likes, independently of the "scene light".
In the photographic vocabulary, 'exposure' by itself doesn't mean 'anything', it quite specifically means illuminance at the plane of focus times the exposure time. That's its well defined meaning and has been since the late 18th century. That's the meaning that is to be found in all the film data sheets, in the ISO specifications of photographic terms and in all texts written by competent authors. It's the root definition for everything else that depends on 'exposure'. If you get that wrong, you get everything wrong thereafter.
As for 'Exposure Value', its definition also depends on the definition of exposure, as it said in the Wikipedia page I linked. 'Exposure Value' is perhaps an unfortunate name, but it is the one we have. @xpatUSA has written:Now everybody except one here will go on about the "amount of light hitting the sensor" or quote CIPA or ISO's formula Hm = na-ni-na or words to that effect -but he makes a valid point albeit a vague one - deliberately so, perhaps.
The point is this, 'exposure' is a jargon word, specific to photographic imaging in this context. It's not a word that lay people will use. Unless a photographer, they won't have much concept of how much light is hitting the sensor, and they won't refer to how light or dark a photo looks as 'exposure', and they certainly won't have a concept of the log2 version of f-number and exposure time. So, it's entirely within the photographic jargon. The point of jargon within fields is to aid precise communication within that field, we ascribe words exact meanings which operate within that field, which avoids ambiguity of discussion. Now if you're going to reintroduce all that ambiguity by playing fast and loose with those precise definitions, then what you're doing is corrupting the possibility of clear communication. You're best off not using the jargon at all. It's more accessible to people not within the field.
Quoted message:Or, was "t-stop" bothersome, if so, why?
T-stop is more precisely correct than f-number. 'In 'Exposure value' it is f-number by definition.
@xpatUSA has written:Being trite, if I go outside and twiddle stuff on my camera, the scene lighting does not change at all - it is independent of my twiddling.
That's right. But exposure changes because of the twiddling. And if you're in a studio with control over the scene lighting, you can twiddle that to change the exposure.
A crushing response! I fold.
Donald was wrong ... again.
Pardon the added levity:
Two photographers at a swan pool ...
A: "What exposure are you using, mate?"
B: "Er, 1/60sec at f/11."
A: "Oh, I just pulled out my Gossen and it looks like that spot-metered swan is reflecting at 1200 candela per square metre so maybe 400 lux at the sensor and it's moving so I was thinking 1/250sec at ... ... ... oh, bugger, it's flown off!"
you forgot to take a raw image race inside turn on the computer download the file into FRV to make sure you had the whites just underclipping then race out side and capture the bird thats flown off because you wanted the perfect exposure 🤣🤣🤣 even though cameras these days are isoless you could have just closed your eyes and taken the image and not even set exposure + iso because it doesnt exist ,camera makers have no idea what they are making as iso control is a gimmick.
@xpatUSA has written:A crushing response! I fold.
Donald was wrong ... again.
Sorry, it wasn't supposed to be 'crushing', just thorough.
Don usually is wrong - doesn't stop him taking nice pictures though (except when it comes to motor sport).
I can take motor sports 😂😂 i just dont take car racing as there is no skill in it ,even using an old pentax k10 with a kit zoom.
BTW the images with no focal lenght are taken with a 500mm manual focus lens that cost me 50 bucks from a garage sale 😁😎😎
@JohnSheehyRev has written: @DonaldB has written: @JohnSheehyRev has written: @DonaldB has written: @ggbutcher has written:Current implementations use the JPEG EVF image, not much use for determining clipping with all the processing applied. I want blinkies based on the raw data.
have you actually tested your histogram accuracy ? because my sony a74 coudnt be any more accurate.
No one who knows what they're talking about has said that the in-camera histogram is not accurate for the camera's conversion or a default conversion. It is BASED on the camera's conversion parameters, so how could it be wrong for that purpose? What it doesn't show you is what is going on in the raw data, and depending on the camera and WB and ISO setting, the amount of raw headroom can vary tremendously. If you want to venture safely into those extended raw highlights, then you would want a raw histogram; not a default conversion histogram.
Wrong ,you need to actually test the cameras you think you know something about. then get back to me.
It's impossible for your camera to always give the same RGB headroom in both raw and display RGB, just because of white balance. Your camera would literally have to alter its filtration of color during exposure, or the raws would have to have WB applied to them (wasting headroom) for your assertion to be roughly accurate. Also, the only time you see headroom in the green channel approximately the same in the raw and display RGB is when the raws have limited headroom, like the "extended" ISO 50 in many FF cameras.
I just compared the Sony A7R2, Canon R5, and Nikon D850 at DxOMark, to see the saturation-based "measured" ISOs, and sure enough, the A7R2 has the least absolute highlight headroom at ISO 100. So, you may see the two histograms looking more similar with your camera than with the others, but that does not mean that your camera histogram is a substitute for a raw histogram, as the red and blue channel histograms will diverge due to WB. You'd have to have a white balance for a magenta light tint, and greyscale subject matter, to expect the two histograms to be as close, consistently. Add highly-saturated highlight colors and WB, and the two histograms will diverge.
Thanks John.
I have always enjoyed your unbiased posts towards members seeking technical information when compareing against practical experience.
i get a bit tired of the usual lets destroy Dons findinds by other members. its like some sort of game to them.
Poor Donald. Your deliberate buffoonery is no game to me.
I have always enjoyed your unbiased posts towards members seeking technical information when compareing against practical experience.
i get a bit tired of the usual lets destroy Dons findinds by other members. its like some sort of game to them.
This is funny,
What John has told you was explained to you something like 1000 + posts ago in the very thread you started " Raw histogram and why does it matter"
This was told to you about 100 times even using your own raw files that showed you the very things John was taking about.
This was also told to you by no less than 5 people as to why, and you fought them tooth and nail, with the attitude that they were wrong and that you would be teaching them something.
The irony
@DonaldB has written:I have always enjoyed your unbiased posts towards members seeking technical information when compareing against practical experience.
i get a bit tired of the usual lets destroy Dons findinds by other members. its like some sort of game to them.This is funny,
What John has told you was explained to you something like 1000 + posts ago in the very thread you started " Raw histogram and why does it matter"This was told to you about 100 times even using your own raw files that showed you the very things John was taking about.
This was also told to you by no less than 5 people as to why, and you fought them tooth and nail, with the attitude that they were wrong and that you would be teaching them something.
The irony
yes the irony and yet still know one can disprove my findings .