Metering modes help

[Mufasa]

I understand how each of the metering modes (spot, centre weight, and evaluative on an XT) work but i am not quite clear on situations you would use other then spot metering. 99% of the time a picture has a focal point and that is what must be metered correctly (in my logic at least) so when would you not just use spot metering on that object?

 

[deanimator]

The spot meter points at exactly and only what is in the middle.

If the middle thing is black, your camera would try to tell you to open up by about three stops, overexposing the shot...the black thing would then be grey.

If the middle thing was white...same problem...would come out grey, and everything else would be underexposed.

HOWEVER...the good news is, point it at a middle grey tone/value in the scene and set your exposure manually, and bingo...GOOD exposure.


Hey...that´s a quick overview. You can get into trickier stuff here if you want to.

 

[gravy]

here's wikipedia...

http://en.wikipedia.org/wiki/Metering_mode

 

[Big Mike]

It doesn't really matter, as long as you know which mode you are and are using it accordingly. If you know what you want to meter, then spot is a good option. If you are in a fast environment and don't have time to carefully meter a certain spot, then evaluative might be better.

Just to clarify...the Rebel XT does not have true spot metering. It has Evaluative (which uses 35 different zones), Centre weighted and partial. The closest thing to spot would be the partial, which only uses the centre section...but it's still a significant area of the image.

 

[panocho]

each metering system adapts better to certain situations, but you obviously can use any of them in any situation. However, as mentioned, you have to know how they work to interpret correctly the camera's metering.

spot metering is the one that requires more knowledge on light and metering, and most of the people will only use it for difficult metering situations.

At most situations, either center-weighted or matrix will give you more easily a nice metering than spot. Portraits, for example, are a typical case for using center-weighted. Matrix can be nicer when you have different subjects somehow dispersed.

But then that doesn't mean each situation has its metering system. It depends on personal preferences and on to which one is accustomed. If you're been shooting almost exclusively with spot and like the results, keep doing it. To me it sounds a little weird, but who cares!

-by the way, I see now that Big Mike clarifies it is not really spot metering you've been using. So that's not so weird...

 

[rmh159]

Another way to use spot metering is in HDR to measure the extremes of the scene and figure out where you need to start / stop while making the exposures. I'm not sure if any other metering mode would be THAT precise.

Personally I use evaluative metering for everything and I don't think I ever been unsatisified.

 

[Mufasa]

Thanks guys for the help. I have noticed before that sometimes the camera would randomly over/underexpose but i guess that was do to trying to meter something black or white.

One quick question about Big Mikes post tho. Does the spot metering on an XT take say 75% of the weight to the centre and 25% to the rest? If so isn't this just alot like center weight?