Ermm . that's the article on 'exposure value' - aka EV. Not exposure. The article on exposure is here
From the first sentence on the article on EV
In photography, exposure value (EV) is a number that represents a combination of a camera's shutter speed and f-number, such that all combinations that yield the same exposure have the same EV (for any fixed scene luminance).
Apologies in advance if my sarcasm meter is not working properly.
As I read it, it is sarcasm and a bit more :)
No sarcasm was intended. He said something right; I passed a complimert.
But, due to the classic Donald aggrieved response, my compliment is withdrawn.
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 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.
What Donald said was
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.
Well, given that 'exposure' is supposed to be one of the core concepts in photography, shouldn't we get it right.
which is wrong
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.
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.
T-stop is more precisely correct than f-number. 'In 'Exposure value' it is f-number by definition.
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!"
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).
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...
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 ...
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.
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 😁😎😎
Poor Donald. Your deliberate buffoonery is no game to me.
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
