Light Meter?

Question

What does a light meter actually do in our picture?
I think we've already have a light meter inside our camera body, then why do we need one more light meter that holding in our hand? Does it make any different?
Can anyone explain to me the usage of this accessories?
Do we need one?

Answer 1

See these tutorials: http://www.net-art.it/photomonitor/html/teoria_tecnica/esposizione/index-e.shtml

Answer 2

The answer to this question should be no if you are just a point an shoot photographer. Even if you are using today's more complex SLR's a hand held light meter is not really neccessary as most models offer a variety of metering choices, whether it be center weighted average metering, overall average metering, or even spot metering. It is the spot metering feature that can replace the incident light readings that a hand held light meter give you.

However, if you are using studio lights, then you need a hand held meter for the flash as it will give you the correct exposure to use.

Answer 3

Hand-held light meters have become obsolete since they started building them into cameras.
The purpose of the meter was to tell the photographer how much aperature and the shutter speed to use. Most had several scales marked on the faceplate. A sample readout might show 1/250 sec @ f/2.8 or 1/125 sec @ f/4 or 1/60 sec @ f/5.6, and so on.
Nowadays the light meters built into the cameras typically show you the shutter speed you should use if you're using aperature priority mode , or the aperature you should use if you're using shutter priority mode. In addition, most built-in meters will show blinking lights if you have too much or too little exposure.