i drove past this one earlier. hoping someone would come up with a real definintion - something like from a physicist, but in plain language. the best that i came up with was two associates with those very rare MFA Photographic Science. my 200+ hours doesn't even get close to these guys.
almost everybody now-days gets really close to it because of the photoshop crutch and the button on the back of the camera. but the nail is getting really messed up. really, until a little while ago, only a few film geeks actually ever saw a photographic histogram. even fewer actually knew the sceince of densitometry and sensitometry. so, there is a lot of mystery attached to this little graph.
folks, "In statistics, a histogram is a graphical display of tabulated frequencies." (
http://en.wikipedia.org/wiki/Histogram). it is nothing more, nothing less.
remember that - "matter can not be destroyed..."
a photographic histogram is a graphic illustration of the tonal values of a given scene. "A histogram is a standard statistical description of a distribution in terms of occurrence frequencies of different event classes; for color, the event classes are regions in color space." (
http://en.wikipedia.org/wiki/Color_histogram) thats all. nothing more, nothing less.
remember that - "matter can not be created..."
1. if the scene being recorded is mostly dark, the histogram will "stack-up" to the left. yes, that is where the shadows record in the sceintific method.
2. if the scene being recorded is mostly light, the histogram will "stack-up" to the right. yes, that is where the highlights record in the sceintific method.
3. if the scene being recorded is an average of darks and lights, the histogram will distribute evenly across the graph. this is where an even distribution of highlights and shadows record in the sceintific method.
there are many test and demonstrations that can be done to demonstrate these phenomenon. remember to approach the proving as a photographic science experiment when you decide to really understand it.
4. remember that you are always trying to record highlights and shadows - both with details for as far as your intended output device will reproduce. remember shadow detail and highlight seperation?
as for using the histogram for the "new light meter," you are all correct as long as the histogram doesn't "stack-up" too far left or right. if you happen to not see that the histogram is just running off the edge, you will find your highlights or shadows have been blown out or blocked up. if you don't run it out far enough, the image will be too contrasty. What no one is talking about is the vertical axis. what if the vertical is pushed off the graph?
i don't know about you guys, but i can't see enough of that tiny little screen to bet my images on it. i shoot all my digital in RAW. i still carry my trusty minolta meters from the '90s. nice large digits, scene averaging, and memory.
class dismissed. have a good weekend
Fri Apr 20, 2007 9:34 pm 
) how do you use the histogram if at all when shooting. Do people have it on so when they shoot it automatically pops up and they can then readjust if neceassary. i do shoot in RAW, but I understand that a) you want to get the shot right first time and b) that too much post-processing increases noise at certain times. Any help on this would be gratefully received 
