View Full Version : in camera light meter
March 31st, 2006, 07:22 PM
hey everyone, I just bought a new canon digital rebel xt, and am trying to learn all I can about it, I am buying books, getting mag subscriptons and talking to everyone I can.What I am trying to figure out now is how to operate the in camera light meter.I have read my hand book over and over but Im still not sure I understand completely.What my question of the day is how do you take a reading with the light meter in the camera,do you keep setting the aperture and shutter speed until the arrow points to the center of the bar graph in the viewer display which I take it means that this is the standard exposure level, or am I completely confused?I am sure that you can tell by my question I dont really have a clue about exposure and shutterspeed.I just purchased a book today titled "understanding Exposure", hopefully this will help me also but could someone walk me through taking a reading with the cameras light meter? thanks
March 31st, 2006, 08:45 PM
Ah, well you don't take a reading with the internal light meter. In 'P' mode the camera sets both aperture and shutter speed. You can set one or the other in Av or Tv and let the camera set the other one. Or you can set both in manual (M). There are all sorts of variations on this but that is the basics.
March 31st, 2006, 11:55 PM
First off, you have to realise that the camera meters for 12-13% grey (a neutral surface that reflects about 12-13% light). Many use a 18% grey card and open up the exposure by half a stop, but you can (naturally) get 12% grey cards as well.
That is the general rule of thumb, but Canon had to complicate this further. If you switch to evaluative metering, IIRC the camera will assume that a certain portion of the upper part of the frame is probably sky, so it'll take into account that this part can be brighter. I believe they started doing that with the 10D?
For me, one of the most useful yardsticks is the sunny-16 rule. If you dial in aperture f/16 and set shutter speed to 1/ISO, then your exposure is set to a bright sunny day. (I never shoot at aperture f/16 of course, but find e.g. f/8 and 1/400s, ISO100 to be useful in many situations) More here: http://www.camerahobby.com/EBook-Metering_Chapter3.htm
IMO, if you have time to plan your shots, then you should shoot in M. Otherwise Av (or Tv in case maintaining shutter speed is more important) is the way to go. In places where the light doesn't change rapidly, go with M. Lecter, Sao and I were visiting the floating market, and we were constantly weaving in and out of the shadows, lecter in Av was way more productive than me in M. (he probably would've been anyway, but the mode played a part too)
April 1st, 2006, 02:59 PM
hey this is me again, so to get a reading do i put the camera on M and then press the shutter half way to get a reading?