Bob, we really need the ignore button here.
April 2, 2023
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He's already been reported to both Bob and Alan 👍
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I agree, I would really like to be able to ignore DannoB's misuse of the terms exposure and proper exposure and optimum exposure.
Bob, can we please have an ignore button?
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It's the same thing, Porky (aka alfn). 'Intensity' means light power density (per unit area). Power times time gives energy. Since light is a quantum phenomenon, so exposure is light energy (per unit area).
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That kind of depends on whose definition of "low light" we're talking about. For some people, shooting evenly-lit scenes at ISO 1600 on a FF camera is considered "low light" and people might not want to see the individual noise variations when they look at high magnification, but for others, like those who shoot small/distant wildlife in shady areas where such wildlife often are found, we might be talking about a crop from a 9x6mm section of a sensor at ISO 25600, and in such cases, read noise becomes very problematic, especially in the red channel, as the cameras are already insensitive to red, and there is also little red light in the shade.
As long as there is visible read noise, it is always a bigger problem than photon noise when you greatly reduce exposure. Relative to signal, read noise generally doubles when you halve exposure, but photon noise only increases 41% relative to signal. So, reducing exposure shifts more and more of the noise towards read noise. When you increase exposure, as you mention above, yes you decrease photon noise relative to signal, but you reduce read noise relative to signal even more. That is the simple answer when you use the same ISO setting and just vary exposure. When you vary ISO setting, too, then there will be some exceptions for read noise with most cameras due to analog and conversion gain differences.
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I've always thought that if people should be able to ignore people without the need for technological assistance. Of course, ignoring people is very discourteous, and only to be deployed when the person in question is a tiresome boring troll.
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Thank you for confirming this, Bob. I defer to your wisdom. Hopefully DannoB will now start using the proper definition of exposure, now that we have worked together to educate him.
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If it is done the dpreview way, it would be invisible to the ignored. The benefit is to compactify the view - no need to scroll down, etc. Also, no need to memorize the screen names of the ignored which they can change.
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ok, I see now......Porky/alfn and David1961 are the same person...got it 👍
dprevived.com/t/why-are-my-photos-noisy/754/post/18302/
Alfn must have seen my post here and didn't like it:
dprevived.com/t/this-is-why-i-dont-miss-dpreview-at-all/2026/post/17465/
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I am still going to run with:
* exposure - amount of light that struck the sensor 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. -
The two definitions are equivalent. I know how much you dislike the concept of equivalence, but there it is.
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Intensity time time is the one usually used in photographic text books, but they amount to the same thing, so anyone complaining about them being different has a comprehension problem.
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Bob has changed my username, which is a silly childish prank and implies the moderators here are no better than those at the septic tank formerly known as DPReview. However such schoolyard antics will not stop me, with Bob's assistance, from educating you on the proper definition of exposure.
I see that you are no longer denying that I am correct but I do not expect you to be man enough to admit you were wrong.
Assuming alfn is the user on DPReview, we are not the same person, but if he or she too was dedicated to setting you straight, and if Porky is a username he or she employed, than I am honoured to be called Porky and will use his or her name with pride. Ba-de-ba-de-that's all, folks!
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Your user name was changed because it seemed that you were impersonating someone else. If you don't like it, just ask and I can do something more extreme.
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"Equivalent" means "equal in value, function, meaning" and they are not, as DannoB's incorrect definition is a simplified one with a narrow application to certain types of photography. It is arguably useful to beginners like DannoB, but the same argument can be made that the exposure triangle is useful to beginners. I do not think it is as the exposure triangle incorrectly teaches that ISO is part of exposure.
I think it is better to educate beginners properly rather than improperly.
As to the concept of equivalence, assuming you mean photographic equivalence, I generally agree with it. However this thread is not about equivalence and I agree with Danno that threads should not be hijacked even by the site owner. This thread is about noisy photos which is a function of exposure but not a function of equivalence as used in this context.
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Some people on DPReview said this place was going to become just like DPReview. I had hoped that was not true but it seems that's the way things are going.
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Actually, it is a bit more general and covers a wider range, when the light can change during the exposure (strobes, etc.).
