Henri Matisse
I been trying to make this transition with a lot of question,sometimes to many,last week with a couple of friends ,we tried to put some lights together and my mind went blank do I really do the same things i used to?? well the key of reading light in photography makes no difference,the light is the same with digital or film,but here is some info..
The earliest type of light meters were called extinction meters and contained a numbered or lettered row of neutral density filters of increasing density. The photographer would position the meter in front of their subject and note the filter with the greatest density that still allowed incident light to pass through. The letter or number corresponding to the filter was used as an index into a chart of appropriate aperture and shutter speed combination for a given film speed.Extinction meters suffered from the problem that they depended on the light sensitivity of the human eye (which can vary from person to person) and subjective interpretation.
Later meters removed the human element and relied on technologies incorporating selenium,Cds and silicon photo detectors. There are two general types of light meters: reflected-light and incident-light.
Reflected-light meters measure the light reflected by the scene to be photographed. All in-camera meters are reflected-light meters. Reflected-light meters are calibrated to show the appropriate exposure for “average” scenes. .
Incident-light meters which measure the amount of light falling on the subject using an integrating sphere (usually, a translucent hemispherical plastic dome is used to approximate this) placed on top of the light sensor. Because the incident-light reading is independent of the subject's reflectance, it is less likely to lead to incorrect exposures for subjects with unusual average reflectance. Taking an incident-light reading requires placing the meter at the subject's position and pointing it in the general direction of the camera, something not always achievable in practice, e.g., in landscape photography where the subject distance approaches infinity.
Spot metering as the name indicates only reads a small spot or portion of the overall image (usually 1% to 3%). This type of metering is useful in any situation where the lighting is extreme. Backlit subjects, macro shots, or even pictures of the moon can benefit from this type of metering. This type of metering is usually found on the more costly upper end cameras.
THE DIFFERENCE FILM VS DIGITAL
In the old days, if your camera (35mm of course) had a battery die on you in the middle of an important shoot, you still had options. I mean after all; the only thing you needed the battery for was the light meter, it’s not like your whole camera will shut down if you have no battery. Oh, I’m sorry . . . if you are using all digital that might have stung just a little bit.
The point was if your battery died, you still had a way to get a good picture. If you were using 100 speed film you could set your shutter speed to whatever the flash sync speed was (usually 1/60th or 1/125th of a second), set your f-stop to f-16, and bracket every shot. Besides the obvious dependency on batteries, there are other differences between film and digital cameras.
No doubt you heard the phrase: "35mm equivalent". This means that the optics are not exactly the same in a digital camera. Since the 35mm SLR camera has been the standard for so long, that’s what newer cameras are compared to. The difference between the two is a ratio of 1:1.4. Simply put, a 35-200 zoom on a digital camera would be like having a 49-280 zoom lens on a traditional 35mm camera.
The main reason the optics are different is because the sensor (the device that actually reads the light) is also a different size. Film cameras use film (sensitive to light) that is placed directly behind the lens. When the correct exposure is calculated, that image is literately burned into the film. Digital cameras use a sensor; that also sits behind the lens. This sensor is made up of millions of individual points that each represents 1 pixel. Once the sensor has gathered the information for each pixel it transfers that data to a digital media card (which can be used repeatedly.)
The sensor is the physical device that gathers information about the quality of light coming into the camera. The process of "how" the sensor goes about gathering information is referred to as "metering". The human eye can distinguish a range of about 16 different f-stops; camera meters only have a range of about 5 f-stops. This is why camera meters are calibrated for a "mid range" exposure of 18% gray, because 90% of the time that is as close as they can get to the human eye. It’s not the camera’s fault that it can not see as well as you do, it’s simply a fact of life.
