"Crop-ability" of images?

Started 3 months ago | Discussions thread
john isaacs Veteran Member • Posts: 5,879
Re: Why?
1

bobn2 wrote:

john isaacs wrote:

bobn2 wrote:

john isaacs wrote:

bobn2 wrote:

john isaacs wrote:

Well, I put up some links, and I'm perfectly happy with them.

For myself, I suggest that ISO and Kodak trumps 'Cambridge in Colour' and Adobe. Another bit from the Kodak Sensitometry workbook, in the glossary they give, for people that are unfamiliar with the terms:

From when ISO was not a parameter that could be set in-camera, but was set by the film type (and adjustable by alternative processing.

Yet when they started producing digital cameras:

"Setting ISO Speed

The ISO setting controls the camera's sensitivity to light. Use a lower ISO setting in brightly lit scenes; use a higher ISO setting for low-light scenes.

NOTE:ISO settings are available in Auto, Landscape, and Close-up modes (unless Long Time Exposure is set). Higher ISO speeds may create a picture that is "noisier" than a picture taken at lower ISO speeds."

The definition of exposure hasn't changed since digital became a thing. And ISO says that ISO isn't a component of exposure. If ISO isn't what ISO says it is, what is it?

Your continued arguing against the facts is pointless. It seems that you just can't bear to admit that you got it wrong.

ISO is a component of exposure.

Not according to ISO it isn't. As I say, it's pointless for you to keep on claiming that ISO is a component of exposure when ISO says it isn't. Who ware we supposed to believe, you or ISO? I'd go for ISO myself.

Or you can propose another term for "exposure settings" other than "exposure settings".

What you want to call a set of controls on your camera is irrelevant. The question in dispute here is whether exposure means the light energy density at the sensor (which is what it does mean) or whether it means how light or dark the picture looks, (which is not what it means).

The facts, of course, are clear;

Yes, they are. And you have them wrong.

there are numerous sources that describe the exposure triangle and exposure settings.

There are lots of sources that say all kinds of absurd things. So there being 'numerous sources' means nothing at all.

When you look at an image on DPR, they display focal length, shutter speed, aperture, ISO, and exposure compensation. Focal length is not an exposure setting, but the rest of them are.

According to you. But what DPR chooses to display from the EXIF is irrelevant to this discussion. It tells you nothing about what 'exposure is'

Your insistence to the contrary; there is little value in your definition because it is insufficient.

It's not 'my definition'. It is the internationally standardised and accepted definition. It is 'insufficient' for what? It's certainly sufficient for defining exposure, because that is what it does.

It's an interesting property of people who have become attached to disinformation. They are often very unwilling to detach themselves from it, however clear it is to everyone else that they have detached themselves from reality.

Your copied definition of "exposure" does not mention "light energy density at the sensor". But you do state "It is determined by shutter speed, f-number and scene luminance", which is clearly not sufficient because there are other factors that affect the light hitting the sensor and especially the light measured by the sensor.   All of which is captured by the ISO and Exposure Compensation (which directly correlate with illumination once the ISO is calibrated).

What you want is for exposure to be a useless concept; because there is no other way to determine  illumination of the sensor.

I can tell you the shutter speed and the aperture, and give you the image, and you cannot make any statement about the "exposure" because you do not have sufficient information.

Which makes the concept useless.

But take shutter speed, aperture, and ISO (and EC if non-zero), and you can have an estimate of the "exposure"; you just need to know what the "real ISO" is to get the rest.

And this is why you get push back on this definition; it is useless.

Finally, as for your definition being the "internationally standardised and accepted definition", that is really a hoot.  There is no such thing.  ISO isn't standardized. Aperture isn't transmissivity.

And I will not respond to your last statement.  But keep it up, and I'll report you.

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