Scene luminance has nothing to do with exposure.

DonaldBlens
Online2386 posts
2 years ago 2 years ago
@GreatBustard has written:

@DonaldB has written:

@GreatBustard has written:

but the exposure it is taking is a function of the scene luminance

then the exposure it is taking is a function of iso also 😊

Yes, you can use the ISO control on the camera to indirectly change the exposure by making the camera choose a different f-number, exposure time, and/or flash power, depending on the mode you're using, and it is those changes that alter the exposure. But the ISO setting, in and of itself, is not an element of exposure, anymore than your fingers or thumb, which you use to change the ISO setting, are part of exposure.

define scene luminance.
Keruskerpanorama_fish_eye
Offline14 posts
2 years ago 2 years ago
@IanSForsyth has written:

I tried to take a photograph with no scene luminance

And this is what I got
So I would think that it is

I would like to see the same but with an exposure of 4 hours (or so).
BTW, the above is the same result as having no exposure (when simplified logic is applied).
So the statement: Scene luminance has nothing to do with exposure. is wrong at least in some cases!

Have fun 😀 - or not 😩
DonaldBlens
Online2386 posts
2 years ago 2 years ago
@Kerusker has written:

@IanSForsyth has written:

I tried to take a photograph with no scene luminance

And this is what I got
So I would think that it is

I would like to see the same but with an exposure of 4 hours (or so).
BTW, the above is the same result as having no exposure (when simplified logic is applied).
So the statement: Scene luminance has nothing to do with exposure. is wrong at least in some cases!

Have fun 😀 - or not 😩

main-qimg-9f712a0068edaddc290119c61478de4f.jpg
JPG, 111.5 KB, uploaded by DonaldB 2 years ago.
GreatBustardpanorama_fish_eye
Offline721 posts
2 years ago 2 years ago
@DonaldB has written:

@GreatBustard has written:

@DonaldB has written:

@GreatBustard has written:

but the exposure it is taking is a function of the scene luminance

then the exposure it is taking is a function of iso also 😊

Yes, you can use the ISO control on the camera to indirectly change the exposure by making the camera choose a different f-number, exposure time, and/or flash power, depending on the mode you're using, and it is those changes that alter the exposure. But the ISO setting, in and of itself, is not an element of exposure, anymore than your fingers or thumb, which you use to change the ISO setting, are part of exposure.

define scene luminance.

The [average] intensity of the light from the scene reaching the lens (average, since the exposure we are talking about is the average exposure).
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DonaldBlens
Online2386 posts
2 years ago 2 years ago
@IanSForsyth has written:

@SrMi has written:

That is not the role of exposure. E.g., the lightness (ISO) and the colors (WB) are not part of exposure.

What happens if I pre WB the light with light modifiers to produce a uniform WB across different light sources in the scene?

If I am modifying my illuminate to cast a different WB differently across my FOV or if I am introducing colored light to a backdrop then WB and color can part of the exposure

its not part of exposure , that is lighting the scene. nothing to do with taking the image nothing.
DonaldBlens
Online2386 posts
2 years ago 2 years ago
@GreatBustard has written:

@DonaldB has written:

@GreatBustard has written:

@DonaldB has written:

@GreatBustard has written:

but the exposure it is taking is a function of the scene luminance

then the exposure it is taking is a function of iso also 😊

Yes, you can use the ISO control on the camera to indirectly change the exposure by making the camera choose a different f-number, exposure time, and/or flash power, depending on the mode you're using, and it is those changes that alter the exposure. But the ISO setting, in and of itself, is not an element of exposure, anymore than your fingers or thumb, which you use to change the ISO setting, are part of exposure.

define scene luminance.

The [average] intensity of the light from the scene reaching the lens (average, since the exposure we are talking about is the average exposure).

define "average" scene luminosity ?
DanHasLeftForumhelp_outline
Hidden4254 posts
2 years ago 2 years ago
@DonaldB has written:

Scene luminance has nothing to do with exposure.

ohNo.gif
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DanHasLeftForumhelp_outline
Hidden4254 posts
2 years ago 2 years ago
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bobn2panorama_fish_eye
Team
Offline2240 posts
2 years ago 2 years ago
@PeteW has written:

Well played, Don. 😉

I suspect that this thread already has a space reserved for it in the Dumpster. It's only waiting for Danno to contribute before the mods send it south.

You misunderstand the purpose of the Dumpster. Your comment here will likely end up there, if it starts an off-topic branch based on snide negativity, which detracts form the conversation. Danno and Don are generally discussing the matter at hand, even if the do go on at it harder and for longer than some people would prefer. It's only when their conversation has got to the point where there is no substantive matter being added that the end bit goes in the Dumpster.
bobn2panorama_fish_eye
Team
Offline2240 posts
2 years ago 2 years ago
@DonaldB has written:

Open for Discussion.

My comment . the camera is taking the exposure, the scene is what it is.

This is a case of the equivocation fallacy.
In photography, the word 'exposure' is used to mean two different things. The Google dictionary includes the two in one definition:
the action of exposing a photographic film to light.
"a camera which would give a picture immediately after exposure"
the quantity of light reaching a photographic film, as determined by shutter speed and lens aperture.
"an exposure of 0.5 seconds at f/5.6"
The latter definition is wrong, because it excludes scene luminance, but this isn't a technical directory. '0.5 seconds ad f/5.6' is an exposure value.
Anyhow, what you're doing is using the first definition - which clearly doesn't include scene luminance, and confusing it with the second, which should, had the Google dictionary got it right.
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Bryanlens
Online1375 posts
2 years ago 2 years ago
@DonaldB has written:

That is priceless.

What is the sound of a low flying 747 overhead
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DonaldBlens
Online2386 posts
2 years ago 2 years ago
@bobn2 has written:

@DonaldB has written:

Open for Discussion.

My comment . the camera is taking the exposure, the scene is what it is.

This is a case of the equivocation fallacy.
In photography, the word 'exposure' is used to mean two different things. The Google dictionary includes the two in one definition:
the action of exposing a photographic film to light.
"a camera which would give a picture immediately after exposure"
the quantity of light reaching a photographic film, as determined by shutter speed and lens aperture.
"an exposure of 0.5 seconds at f/5.6"
The latter definition is wrong, because it excludes scene luminance, but this isn't a technical directory. '0.5 seconds ad f/5.6' is an exposure value.
Anyhow, what you're doing is using the first definition - which clearly doesn't include scene luminance, and confusing it with the second, which should, had the Google dictionary got it right.

My thread title was

Scene luminance has nothing to do with exposure.

I didnt write "an exposure"
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SrMipanorama_fish_eye
Offline457 posts
2 years ago 2 years ago
@DonaldB has written:

@SrMi has written:

Exposure determines how much light hits the sensor. That depends on shutter speed, aperture, and scene light.

Exposure doesnt include scene light. exposure is shutter, and t stop.

That is wrong.

Please read Jim’s article, it includes the definition of exposure:

www.lensrentals.com/blog/2023/05/how-digital-cameras-determine-exposure-part-1/
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DonaldBlens
Online2386 posts
2 years ago 2 years ago
@SrMi has written:

@DonaldB has written:

@SrMi has written:

Exposure determines how much light hits the sensor. That depends on shutter speed, aperture, and scene light.

Exposure doesnt include scene light. exposure is shutter, and t stop.

That is wrong.

Please read Jim’s article, it includes the definition of exposure:

www.lensrentals.com/blog/2023/05/how-digital-cameras-determine-exposure-part-1/

Iso/asa and scene lightness are both used to determining exposure. but it isnt "exposure"
would you say fill flash is scene lightness ?and part of determining exposure ?
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DanHasLeftForumhelp_outline
Hidden4254 posts
2 years ago 2 years ago
@DonaldB has written:

Exposure doesnt include scene light. exposure is shutter, and t stop.

oh dear. I don't fancy your chances of winning this argument especially since you have a school kid wannabe troll agreeing with you 🤣😎 and you keep changing what you mean by "exposure". You and Porky need to get your stories straight before posting if you need to be taken seriously 😎

dprevived.com/t/for-fans-of-porky/3893/post/47725/

@Porky has written:

@DannoLeftForums has written:

You also posted DonaldB knows the correct definition of exposure after he posted in another thread that exposure is how light or dark an image looks on the medium it is being viewed on.

You are just mad because DonnaB knows the proper definition of exposure and you do not!!

You have one very confused school kid supporting you 😃 but obviously he's not sure what exposure is himself 😀😎

@Porky has written:

E = I x T. Exposure equals intensity plus time. That is the definition of exposure.

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bobn2panorama_fish_eye
Team
Offline2240 posts
2 years ago 2 years ago
@DonaldB has written:

I didnt write "an exposure"

You wrote

@DonaldB has written:

the camera is taking the exposure

The sense is clearly the same. 'Taking an exposure' can only mean an exposure, in the sense of a synonym for 'a photograph'.
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bobn2panorama_fish_eye
Team
Offline2240 posts
2 years ago 2 years ago
@DonaldB has written:

Iso/asa and scene lightness are both used to determining exposure.

The scene doesn't have lightness - it has brightness. Lightness is a characteristic of a reproduced image, not a scene. You need to sort your concepts out.
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DonaldBlens
Online2386 posts
2 years ago 2 years ago
@bobn2 has written:

@DonaldB has written:

Iso/asa and scene lightness are both used to determining exposure.

The scene doesn't have lightness - it has brightness. Lightness is a characteristic of a reproduced image, not a scene. You need to sort your concepts out.

bright pink and light pink or just pink ?