Why are my photos noisy - discussion

Here is an article from Sony which pretty much has it right in terms of correctly differentiating exposure* and image lightness.

www.sony.com/electronics/support/articles/00267925

The article starts off with:

"Exposure is the amount of light coming into the camera when shooting a photograph."

which is very similar to - amount of light that struck the sensor per unit area while the shutter was open.

It then says:

"The amount of light is determined by the aperture and shutter speed."

which should really also include scene luminance. The important thing to note is that Sony say that ISO is not part of the exposure as they define exposure.

They then go on to say:

"These, combined with ISO sensitivity, determine the brightness of a photograph."

which is effectively what I and many others have been saying in that ISO is an image lightness, not exposure*, parameter.

Therefore this article from Sony also confirms what I posted earlier:

For a given scene lighting:

f/8, 1/400s, ISO 200

and

f/8, 1/200s, ISO 100

will output the same image lightness (or brightness if you like) but the ISO 200 shot will have had only 1/2 the exposure* of the ISO 100 shot and so the ISO 200 shot will have more visible noise than the ISO 100 shot.

The bottom line here is that Sony are saying that according to their definition of exposure, exposure is not how light or dark an image looks.

* exposure - amount of light that struck the sensor per unit area while the shutter was open
** optimal exposure - the maximum exposure* within dof and motion blur requirements without clipping important highlights.
*** under exposed - more exposure* could have been added with the DOF and blur constraints still being met without clipping important highlights.

exactly. it will settle down, everyone is just letting loose after such a long period 7 years of moderation on DPR . in any case how long can one discuss the most simple processes of photography "exposure" noise and iso. at least there's been no brand bashing, trolling and equivalence. when its all settled down the threads should be deleted and start all over again.

@JohnA: Can handle that. Just voiced my opinion. The worth of it might be zero, or it might be not. I don´t know. I am aware of that balance. Can´t have the cake and eat it too.
@DonaldB: Presenting facst goes long way, and can be spam still. Sky is blue -well, what does it have to do here...
It would be nice to find what the topic claims to be, not hundreds of OT posts. That´s about it.

ISO Sensitivity
In digital cameras, the ISO sensitivity is an indicator to show how much the light coming from the lens is amplified in the camera.
The amount of light coming into the camera is determined by the aperture and shutter speed. From this amount, the light is amplified to create a well-exposed image. The ISO sensitivity represents the level of this amplification numerically. For example, ISO200 is twice as sensitive as ISO100. This means that adjusting the setting to ISO200 lets you shoot with the same brightness as ISO100 even in half the amount of light.
Actually, in most modes, the ISO sensitivity is automatically determined by the camera according to shooting conditions. However, in the P/A/S/M-modes, you can also set it manually depending on your needs.
As the sensitivity gets higher, you can use faster shutter speeds even in low-light situations to reduce blurs caused by camera shake under low light or subject movement in sports shooting. However, because the light is amplified electrically, shooting with the high ISO sensitivity tends to result in more noise (grain) or loss of sharpness on the photograph.

You post very few facts. Even Sony say that exposure is not how light or dark an image looks, where you claim it is, according to the article I linked to earlier 🙂

It failed to say “per unit area,” and that “coming” can be interpreted as “per unit time,” which would be wrong. ”Light” is right though. 🙂

You are quoting statements that are not even correct because the light is not amplified in the camera.

If you need to be taken seriously, post where you think the light is being amplified in the camera.

i was answering your post "Sometimes I can't even begin to fathom how your brain works, if that's the right word for it." now you know and so does danno. 😁

its from the Sony page.

I know it's from the Sony page and I posted why the statement is not correct.

If you need to be taken seriously, post where you think the light is being amplified in the camera.

I also posted a link where Sony say that exposure is not how light or dark an image looks.

i just posted the whole Sony page. you selectively keep leaving things out.

One stop here refers to drop in noise but that corresponds to two stops in exposure. So the math is OK.

There are other problems with averaging- it may be done after demosaicing to align frames, etc.

I haven't left anything out. I posted a link to the entire Sony article.

I also posted a link where Sony say that exposure is not how light or dark an image looks.

I'm sure anyone interested can read the article for themselves and see that what I said is consistent with it.

thats what i noticed the frames are just not aligned perfectly in camera . also what happens when i stack 60 images in zerene ,with a noisy camera sensor even at base iso the software stacks the noise and then its blobs of noise.

Yes, I know how your brain works as I posted earlier:

"It's very easy to see what he does. When he has been proven wrong and has run out of arguments to try to justify his opinions, he uses a scatter gun approach to going off on fairy tale tangents to try to disguise his lack of understanding of basic photography concepts."