Herb, I am not in conflict with this term, nor am I saying you can't use it any way you want. There are some areas where one may generate some quiet chuckles from older folks if one uses the word "dynamic" where it's not appropriate, however. Toward the end of this post, I'll bring this back to photography.
So far we have been talking primarily about equipment. This has been a mistake. It's all to easy for us engineers to become too engrossed with the equipment we are designing, using or buying, their specifications, capabilities etc. We forget, or push back to another compartment of our mind, the fact that this is all reproduction equipment. I'd say that this happens in engineering texts too, but in fact, it's there, in the word "dynamic" itself. I am saying that the music existed before the the record player was invented, and Images worthy of being recorded existed before the first camera, even before the first paint brush. Let's look at music first. It's a reasonable analog to part of the process. We'll get back to cameras shortly. What qualities does music have? Well, there's a range of frequencies. That would be bandwidth or frequency response. There's loudness, usually measured in spl. Oh yes, and there is variation in the loudness. (There are, of course many other qualities, but I'm not going to get into them here.) This variation in loudness can sometimes be quite great. Ever listen to the "New World Symphony (No. 9)", Dvorak? Well, this loudness range in the music is called, ah... guess what? "Dynamic Range!" For an instrument, it's the range of the softest to the loudest sound that can be produced by an instrument. For a performance, it's the difference in signal level between the loudest and quietest parts of a performance. Note - this is important - the loudest and quietest parts do not occur at the same time. The music is continually changing throughout the performance! This is why it's called "dynamic"! From the dictionary - "Of or relating to variation of intensity, as in musical sound." Note the word variation. When loudness varies, the relation is to time. So variation with time is inherent in the word "dynamic." As to the equipment, The specification for the amplifier is driven by the dynamic range of the sound it must reproduce. So, a peice of electronic equipment that is said to have a certain "dynamic range" has it because it must reproduce or generate something else (music?) that actually has the property of "dynamic range." I suppose it would be more accurate to say that the equipment supports a dynamic range, but nobody's going to use all those words. This is consistant with every other area of engineering wherein the words "dynamic" or "dynamics" is used. When you were studying engineering, you most likely took courses in "Statics and Dynamics" I still have my old texts. What was the difference? Ah, Dynamics included objects that moved (had velocity) and had other properties measured per unit time! Now, on to digital photography. The scene before us is usually dynamic. Even if it's the Rocky Mountains, the light is changing. Even if it isn't changing, (studio still life) we use the camera for different scenes and switching from one scene to another or moving from one view point to another produces the dynamics of range. Since the scene is dynamic, each sensor must be capable of measureing an acceptable range of light and it must be able to react to changes in level as we frame, focus and as lighting changes. The problem presented to the sensor is dynamic and the sensor must possess the dynamic range to to follow the scene. Once we "snap" the "shutter", All becomes static. Nothing of the recorded scene moves again. From pixel to pixel, there is change, perhaps great variation, but it's static, not moving. The variation is over space, not time. Now, initially, the scene is recorded in a fashion that could accommodate variation over time (raw), but it's not changing - static. We can convert it to a jpeg. This removes even the capability to accommodate variation over time. Now it's not only static, it doesn't even have the capability to be dynamic. In order to modify the image it must be converted back to a raw format. If you want dynamic range in your recorded images, get a video or motion picture camera. Anyway, that's my opinion, derived from... history. Regards, Bob... ---------------------------------------------------------------- They call it PMS because Mad Cow Disease was already taken. From: "Herb Chong" [EMAIL PROTECTED] > definition from 2nd Edition, McGraw Hill Dictionary of Scientific and > Technical Terms: "dynamic range (electrical engineering) - the ratio of the > maximum signal level capacity of a system or component to its noise level, > usually specified as decibels." capacity, not what happens during use. no > time. imaging sensors capture all of their signal simultaneously. what's the > maximum possible, what's the minimum possible, and what's the difference. > > From: "Bob Blakely" <[EMAIL PROTECTED]> > > > > time variation has nothing to do with the definition. > > > > No, but it's implied. If there were no variation, there would be no need > for > > range, dynamic or otherwise. The sound varies in level with (guess what) > > time. That is, for example, music is dynamic! Meaning changing, with what? > > Time! It cannot be predicted by the amplifier. This is why the range is > > necessary, and why we call it dynamic. If it did not change with time, we > > would call it static range! When we say dynamic range, we mean the range > is > > provided to accommodate the dynamic (not static) nature of the music (or > > other sound). > > > >
