metering and AI servo? AV mode?

[mpphoto12]

I mainly shoot in manual but what exactly is aperture priority mode or how do you use AV mode on my XT. The Aperture is all controlled weird. How does this work and which situations do you use it in? Im not familiar with this. Also, with sports its best to use Ai servo focusing right? but how does that work? I would like to know how to use my camera more than just manual. ANyone familiar with the TV mode? i dont even know what it does. Sometimes i rather not shoot on manual due to constantly changing lighting conditions. Also what are the different types of meting (or is it braceting?) in the camera. There are different symbols for the others which is best what types of scenarios etc. thanks

[ShutterbugJohan]

what exactly is aperture priority mode or how do you use AV mode on my XT


Aperture Priority mode lets you set the aperture and the camera automatically sets the shutter speed for a proper exposure.



How does this work and which situations do you use it in?


I use it about 80% of the time; the rest of the time is shoot in Program or Manual. (i mainly use manual when using flash.)



Also, with sports its best to use Ai servo focusing right? but how does that work?


Yes. AI Servo AF keeps autofocusing constantly, versus One-Shot AF, which focuses and lock the focus.



ANyone familiar with the TV mode? i dont even know what it does.


Shutter Speed Priority, it is the opposite of Aperture Priority and it lets you set the shutter speed and the camera sets the aperture for a proper exposure.



Sometimes i rather not shoot on manual due to constantly changing lighting conditions.


I would recommend using Program or Aperture Priority.



Also what are the different types of meting (or is it braceting?) in the camera. There are different symbols for the others which is best what types of scenarios etc.


The 3 types of metering on the XT are:

Partial--meters a small section of the frame. I use this and the exposure lock (* button) for portraits and meter off the face.
Center-weighted--meters the whole frame, but gives more priority to the center area.

Evaluative--best for most situations, meters the whole frame and averages the exposure.

[mpphoto12]

oh wow thanks so much that clears up alot :) do you know which symbol is the evaluative metering? is it ok to use it almost all the time?

[Jon Ruyle]

Here is a rant.


I don't like the words "aperture priority" and "shutter priority". They made sense when iso was determined by a roll of film and thus could be considered unchangeable, while the user could change aperture and shutter from shot to shot. But today, there are 3 parameters to exposure: aperture, shutter, and iso. In aperture priority mode, the user chooses aperture and iso and the camera makes the shutter speed what it has to be. So aperture and iso are treated the same, and shutter is the odd man out. Similar for shutter priority.


It would make sense to name the exposure mode after the odd man out instead of after one of two user determined parameters. Ie, there could be 3 modes: "variable shutter" (in which the user selects iso and aperture and the camera makes the shutter what it has to be... this is the same as what is called aperture priority now), "variable aperture" (like current shutter priority) and "variable iso" (user selects aperture *and* shutter, and camera makes iso what it has to be... this is how auto iso *should* work)


I don't care so much about the names, except that I think this legacy terminology has us thinking of iso as being a different sort of parameter than shutter speed and aperture (which it once was but is no longer), and I think this thinking has robbed us of a real "variable iso" mode. (Instead of our current "variable iso", which just has the camera try to guess *two* parameters instead of one... makes no sense to me.)


Ah well. I think canon will get it right one day.


Okay. Done with rant. I feel better now.