Good source for technical understanding?

Started 6 months ago | Questions thread
FingerPainter Senior Member • Posts: 5,493
Re: Cambridge in colour is correct

Christof21 wrote:

FingerPainter wrote:

"WryCuda wrote:

Cambridge in Colour is not a bad place to start. It's written by a scientist, so is fairly authoritative,

While some of his definitions are badly off, the real problem is the incorrect statements he makes. For instance his page on "CAMERA EXPOSURE" makes the following incorrect statements:

  1. How light or dark your image will be is only affected by three camera settings.
  2. ISO controls the sensitivity of your camera's sensor to a given amount of light.
  3. Higher ISO speeds dramatically increase image noise.

If the first statement was correct, if you used settings of 1/125, F/4 ISO 200 in a dark room and on a sunny beach you'd get images of the same brightness. You don't. The amount of light in the scene is one of four factors that determines how light or dark your image will be. Three of those four factors are camera settings.

It is really excessive to pretend this is wrong. Because you iforce a given interpretation..

How light or dark your image : means for me for a given image/scene !!

He doesn't say that. He could have said that, and then the statement would have been correct.

He says affected by three camera settings !! He only refers to the camera settings, things under your control, no other camera setting affect brightness.

The scene luminance can sometimes be under the control of the photographer.

Of course he could clarify better but in my opinion you go too far by saying this is wrong.

It is wrong as written.  A beginner doesn't know to assume the context that you assume for this point and the third point.

If the second statement was correct, the sensor would collect a different charge from a given number of photons striking it if the ISO changed. But it doesn't. For a given amount of light, the sensor collects the same charge regardless of the ISO setting. The ISO setting actually affects what the camera does with the charge the sensor reports.

Here you forget the context... He is talking about the exposure triangle.

While that context, if stated, may affect the third point, it does not affect the second point. He specifically said "for a  given amount of light", and in context that means a specific amount of light hitting the sensor, not a specific scene luminance.

In this logic, when you change one of the 3 setttiins, you have to change the other 2 settings:

"One can therefore use many combinations of the above three settings to achieve the same exposure"

Changing the ISO alone doesn't change the exposure.

If the third statement was correct, If you took a photo at 1/125, f/4, ISO 200, and found it was too dark, and therefore increased ISO to 1600 while leaving shutter and aperture unchanged, and took a second photo in the same light, the second photo would be much noisier than the first. It won't be. Depending on which camera you used, the second photo would either be no more noisy, or a bit less noisy.

Correct again for the same reason, you forget the context

And again, a beginner cannot assume the context.

Cambridge in Colour, like the vast majority of web resources on photography, including the Digital Photography School linked to by Nick_Brisbane ITT, just repeats the same common body of misinformation on the nature of exposure, noise and ISO. There are very few web resources that don't get these subjects wrong. DPR's articles on noise are among of the few exceptions that get it right. The Wex Photographic Beginners videos, make far fewer mistakes than most.

This is not misinformation in my opinion, this is a really great site.

The statements made, are wrong on their face. If you want to consider that their flaw is that they fail to state assumptions the author is making, rathher then being false even with those assumptions, go right ahead.

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