Time of exposition versus ISO value

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Originally Posted by xpatUSA

Well said, Urban.

I find the phrase "dynamic range" especially irritating when it is stated without qualification, leaving the reader to guess which of it's several definitions is applicable.

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You might find this to be the case, but I'm willing to bet that the average photographer really doesn't care. They are probably more interested in the practical impact of how this will impact their images.

I would have to agree that "dynamic range" is not particularly descriptive of the property that we are discussing here.

When I first got into serious photography (around 1970) we spoke about how many "stops of light" a specific film would record. "Stops" were obviously not technically correct as we could get the same result by fixing the aperture and changing the shutter speed, so some brilliant person came up with / popularlized the concept of eV (which frankly is a pretty convoluted approach in trying to explain things as well), This was obviously not obscure enough so somewhere along the term "dynamic range" worked its way into the popular photography jargon. I still have a problem with the concept of describing what is essentially a static property as "dynamic". At least the "range" part makes sense.

End of my rant (for now). :D

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Originally Posted by GrumpyDiver

You might find this to be the case, but I'm willing to bet that the average photographer really doesn't care. They are probably more interested in the practical impact of how this will impact their images.

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Can't argue with that, Manfred. The tone of the response though makes me wonder if this forum is intended to be more for the "average photographer" than those interested in technical matters? Or, did I misunderstand?

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I still have a problem with the concept of describing what is essentially a static property as "dynamic".

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Allow me to explain: "dynamic" refers in our context to force or power - in our case, power.

http://www.dictionary.com/browse/dynamic

Most things in imaging are based on power. Literally. Luminance, illuminance, exposure, etc. all have units of power buried in their [technical] definitions.

However, many people tend to relate the word to motion and that is a stretch, IMHO.

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Originally Posted by xpatUSA

the "average photographer"

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Keep in mind that averages change over time.

The average photographer of 1880 was a pro who had to know how to spread an emulsion on a glass plate (and perhaps make the emulsion), move the plate to the camera without getting dust on it (or when making shots in the desert, without getting dirt blowing in the wind on it), release the shutter before the emulsion dried, remove the plate from the camera and start the entire process all over again with the next plate.

The average photographer a century later only had to know how to put a cassette of film in the back, release the shutter and remove the cassette. That's because point-and-shoot film cameras were readily available.

Thanks to the cell phone, the average photographer of today has never used a standalone camera of any kind.

So, if you want to open up yet another can of worms, continue referring to the "average photographer" without defining what you believe the skill set to be. :D

Personally, I believe only 1% of photographers using a DSLR have any interest whatsoever in the details you guys are discussing about the various definitions of "dynamic range." I believe that because I've never seen any sort of discussion in either of the two photography magazines I've been subscribing to for years. If the business managers of those publications believe there is no viable market with an appetite for that stuff at least every once every other year, they're probably right.

Sorry, when I answered the question it appears I made the huge mistake of somehow not realizing that someone would think that adjusting time and ISO would have an affect on the scenes dynamic range. I had assumed the context in which the term dynamic range was used would be sufficient for them to realize I was referring to the camera/sensor dynamic range to provide a straight forward answer. I think it would be more helpful if this forum would focus more on simple answers rather than using it as an opportunity to show off largely irrelevant technical knowledge. To me photography is an art based on science and technology not a study of the science and technology.

P.S. I used the term focus so I assume this will cause total confusion as to what meaning of focus I was referring to.

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Originally Posted by pnodrog

I think it would be more helpful if this forum would focus more on simple answers rather than using it as an opportunity to show off largely irrelevant technical knowledge.

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I would like to think that people aren't using the forum to show off their own knowledge, but I do agree that most people by a very wide margin have no interest in the technical details. I also agree that those details are largely irrelevant when it comes to learning how to improve one's photography. If they really were relevant, I would never be able to improve because I'm clearly not smart enough to understand them.

Time to count to 10.

Personally, I like the fact that this forum mixes technical and simpler explanations. I enjoy learning new technical things from the people here who know more than I do, like Ted, Manfred, and Bill (WW), among others, and when someone gets into more detail than I want, I just don't read it. At the same time, I agree with Paul in that I think we do need to attend to the level of technical expertise of people participating in a particular thread, particularly the OP. That's why I often add a post summarizing and trying to simplify a discussion. I think that when the responses to a simple question develop into two forks, one complex and one not, it would be nice to separate them, but I suspect that there is no easy way to do this. So, I just pick and choose as I read through the thread.

Mike, I agree that some of the details don't in the end help us improve the outcome, but in my experience, sometimes they do. For example, the technical discussions I have read here have helped me deal with blown colors in flower photographs (need to go back and review some of Ted's postings on saturation to take the next steps with that), to take better high-ISO photos, and to improve in other respects.

Just speaking for myself, I find the tone of the discussion on this forum both civil and unusually constructive, and while I may be naive, I don't see people as showing off. Paul, I too had made a simple comment about dynamic range before Ted posted, but I didn't see his post as trying to put me down. Likewise, when I told him he was wrong about aspect of the math, he didn't get offended.

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Originally Posted by DanK

I find the tone of the discussion on this forum both civil and unusually constructive

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That, for me, is the important issue. Even when the posts aren't constructive for me for whatever reason, I almost always have the feeling that the posts are written with the intent of trying to be constructive. All of us learn in our own ways, so I also recognize that it's unreasonable to expect that anyone can reliably write a particular post, especially if its content leans toward the more technical side of things, that ends up being constructive for everyone.

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Originally Posted by Mike Buckley

So, if you want to open up yet another can of worms, continue referring to the "average photographer" without defining what you believe the skill set to be. :D

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Mike, if "you" means me, I ain't he :D

I was quoting Manfred's phrase.

Well, in 20+ posts no one said "Hold on a minute, there is a good reason why you should shoot a stationary subject at a higher ISO". We all agreed that using a higher ISO is a necessity for keeping the shutter speed high to avoid possible blur.

What I found more interesting though, is that, despite what Wikipedia says, it seems that dynamic range is called dynamic not because the signal is rapidly changing but because this term came from acoustics where it is defined via the ratio of signal powers (rather than the ratio of signal amplitudes), and power is dynami in Greek.

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Originally Posted by xpatUSA

Mike, if "you" means me, I ain't he :D

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Nah, I was referring to anyone who wanted to pay attention to my post, which was probably nobody. The people who didn't want to pay attention are the people I respect the most. :D

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Originally Posted by xpatUSA

Allow me to explain: "dynamic" refers in our context to force or power - in our case, power.

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Time to get pedantic.

Looking at the dictionary definition you linked to I do have a problem with part of their definition:

"Physics.

a. of or relating to force or power.

b. of or relating to force related to motion."

Force and dynamic? Force can equally be applied to a static situation. A camera sitting on a tripod exerts a force on it, but (hopefully) neither the camera nor tripod are moving. I have no issues at all when it comes to the rest of the definitions as they all imply an element of (elapsed) time.

I'm going to stick to SI measurements for the sake of simplicity... :)

In the branch of physics known as mechanics (classical mechanics to be more precise) it is usually divided into three categories: statics (the camera sitting on the tripod example), kinematics (the study of motion without regard to the forces that caused the motion) and dynamics (the study of motion that includes forces and mass). The moment motion comes into question, we determine how far something has moved in a given period (m/s).

If we are looking at the energy side of things, then power, measured in Watts (W) is the number of Joules /second (J/s) and once again time is a key factor.

So anything that is dynamic from a classical physics standpoint involves something over a period of time, which is the point I made in #21.

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Originally Posted by GrumpyDiver

Time to get pedantic.

Looking at the dictionary definition you linked to I do have a problem with part of their definition:

"Physics.

a. of or relating to force or power.

b. of or relating to force related to motion."

Force and dynamic? Force can equally be applied to a static situation. A camera sitting on a tripod exerts a force on it, but (hopefully) neither the camera nor tripod are moving. I have no issues at all when it comes to the rest of the definitions as they all imply an element of (elapsed) time.

I'm going to stick to SI measurements for the sake of simplicity... :)

In the branch of physics known as mechanics (classical mechanics to be more precise) it is usually divided into three categories: statics (the camera sitting on the tripod example), kinematics (the study of motion without regard to the forces that caused the motion) and dynamics (the study of motion that includes forces and mass). The moment motion comes into question, we determine how far something has moved in a given period (m/s).

If we are looking at the energy side of things, then power, measured in Watts (W) is the number of Joules /second (J/s) and once again time is a key factor.

So anything that is dynamic from a classical physics standpoint involves something over a period of time, which is the point I made in #21.

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Sorry. I will recant, so as to keep things simple:

Most things in imaging are not based on power. Neither luminance, illuminance, nor exposure have units of power buried in their [technical] definitions.

Gosh! I'm glad I was sound asleep in bed while all this was going. But I did have a good laugh and learned a little while reading it all this morning. :D

I'm sure Antonio has had his question answered and learned a new English word. I must congratulate him on his current standard of English, it's not an easy language to learn. (99% of Americans and Australians don't even realise that English is a foreign language and will never be able to understand it fully). :D:D:D

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Originally Posted by DanK

. . . I like the fact that this forum mixes technical and simpler explanations.

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Me too.

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Originally Posted by DanK

. . . I enjoy learning [all aspects of any] new [edit] things from the people here who know more than I do . . . and when someone gets into more detail than I want, I just don't read it.

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Me too. I read many more threads than those I in which I comment - probably five times as many. I suspect other do too.

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Originally Posted by DanK

At the same time, I agree with Paul in that I think we do need to attend to the level of technical expertise of people participating in a particular thread, particularly the OP. That's why I often add a post summarizing and trying to simplify a discussion. I think that when the responses to a simple question develop into two forks, one complex and one not, it would be nice to separate them, but I suspect that there is no easy way to do this. So, I just pick and choose as I read through the thread.

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I have two comments to make on this point:

Firstly I believe that it is not generally a good idea to ASSUME the ABILITY of any OP to understand, comprehend or find value in commentaries which are technical and/or complex in any other aspect.

Secondly I think that conversations developing into two (or three or more forks) is value added. This is one aspect of CiC and the flexibility of NOT rigidly “staying on topic” which is so appealing and historically what the “FORUM” was all about.

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Originally Posted by DanK

I find the tone of the discussion on this forum both civil and unusually constructive, and while I may be naive, I don't see people as showing off. Paul, I too had made a simple comment about dynamic range before Ted posted, but I didn't see his post as trying to put me down. Likewise, when I told him he was wrong about aspect of the math, he didn't get offended.

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On another note, and off topic, I think that, if we all are introspectively honest (especially those of us who make commentaries often) we each know the exact purpose(s) of our commentaries. Also worth noting is that our purposes might NOT be how others interpret those purposes. I think it is always best to initially READ each commentary from a perspective that its purpose was attempting to assist and add value and to move the conversation forward.

WW

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Originally Posted by xpatUSA

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Most things in imaging are not based on power. Neither luminance, illuminance, nor exposure have units of power buried in their [technical] definitions.

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If I may be permitted to be pedantic for a minute:

Luminance is measured in candela per square metre. One candela is the luminous intensity of a source that emits radiant intensity of 1/683 watt per steradian. And watt is a unit of power. So power is buried, albeit deeply, in the definition of luminance.

Sorry, Ted, I couldn't resist:(

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Originally Posted by TonyW

If I may be permitted to be pedantic for a minute:

Luminance is measured in candela per square metre. One candela is the luminous intensity of a source that emits radiant intensity of 1/683 watt per steradian. And watt is a unit of power. So power is buried, albeit deeply, in the definition of luminance.

Sorry, Ted, I couldn't resist:(

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No need to apologize, Tony.

So let me get this straight:

Originally, I said:

"Most things in imaging are based on power. Luminance, illuminance, or exposure have units of power buried in their [technical] definitions."

Then I was told how wrong that was.

So, to keep life simple, I recanted by just stating the opposite:

"Most things in imaging are not based on power. Neither luminance, illuminance, nor exposure have units of power buried in their [technical] definitions."

And now I'm told how wrong that is.

Glurk, glug, please get my padded cell ready, I'll be there direckly :D

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Originally Posted by xpatUSA

. . .

Glurk, glug, please get my padded cell ready, I'll be there direckly :D

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There should be room in mine.

Ah've been limiting myself tae reading only 2/3 posts, at a time, in this thread; then, going for a wee lie down with a cold compress on ma forehead.

Was originally gonnae read it all in one go...what a laugh that would've been:confused:.

So, ah'm thinking ....at the very beginning (and bearing in mind what Antonio actually said)...why did no-one simply suggest he try bracketing, then choose which image looked best...tae him? :cool:

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Originally Posted by TonyW

There should be room in mine.

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Just check out his vocal dynamic range first. You don't want a noisy cell mate....:)

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Originally Posted by tao2

Ah've been limiting myself tae reading only 2/3 posts, at a time, in this thread; then, going for a wee lie down with a cold compress on ma forehead.

Was originally gonnae read it all in one go...what a laugh that would've been:confused:.

So, ah'm thinking ....at the very beginning (and bearing in mind what Antonio actually said)...why did no-one simply suggest he try bracketing, then choose which image looked best...tae him? :cool:

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Because Antonio never mentioned trying to capture a scene's dynamic range, he wanted to know the difference between choosing ISO settings and how would it affect his final image. I would have suggested he capture an image with both settings, post the two images on this forum and then either find the difference for himself or have someone point it out to him; if there is a noticeable difference to be found.