Canon 20d/30d/40d Metering Issues

[Lenny Hartley]

I used my canon 40d with canon 70-200 2.8 L is for the first time the
other day, I was shooting at a motorbike racing meeting, and the metering
was jumping about all over the place, I usually setup for AV so I can control depth of field and modify ISO to control shutter speeds,
However the metering was jumping about +/- two stops making it
impossible to know what was going on, I eventually setup for manual
which was fine as long as I knew what I was wanting to shoot but if
something happened in another direction I would not be able to point and
shoot, I also noticed similiar issues with a 20d but only when I was
using a pentax 645 lens with zoerk adaptor but it was no problem as
I was shooting manually anyway, however the issue with the 40d is more
serious as I need to shoot automatically, I did not notice the same
issues with my 100-400 L is lens fitted but I didnt use it much!!!
I spoke to another photographer at the event who told me that he
had sold his 30d due to the same problem.
Anybody else seen this ?

[Ron Metz]

Lenny,

I shoot kids soccer and baseball with my 40D and 30D and the EF 70-200mm f2.8L IS lens and have not experienced what you have. I also shoot in AV. Now, you probably know this but I am going to mention it anyway because I experienced it. If you have the ON/OFF switch up all the way, it activates the quick control dial on the back of the camera. If you are not aware that it is activated, you can very easily move it without knowing it and change your exposure to over or under your "correct" setting. Thanks.

Ron

[Noel_Carboni]

What metering mode have you chosen?

Without knowing that answer I'm going to hazard a guess that you accidentally have it set to spot metering, which is measuring the object at the center of the image for the exposure. I recommend Evaluative metering mode, in which the camera software looks at the entire field of view and chooses exposure settings.

Using Evaluative metering I rarely see an image with my 40D that's more than a fraction of a stop off, exposure-wise (the same was true of my 20D). I've come to trust Evaluative metering.

-Noel

[Will_Mass]

We also use Evaluative Metering for outdoor events. Adding +1 stop EC on the 40D's, +2/3 stop on the 20D's. Haven't seen the described behavior on either of those models.

[Lenny Hartley]

I was using spot metering however I was shooting a burst at the same target so was not moving the "spot" about into dark and lighter areas, I used it again today and no
problem with all the same settings, the only difference I can think of is that the temp
was a lot higher in mid to high 20's C last week, I will try evaluative mode thanks
for the reply's
lenny

[Lenny Hartley]

I have used a few times since the issues with metering and it has been ok with the same settings as before, will keep an eye on it but suspect temp may have something to
do with it, however we dont get many days in the mid to high 20's c in Scotland
so will probably be a while,

[Doug_Kerr]

Hi, Noel,

Originally Posted by Noel_Carboni

Using Evaluative metering I rarely see an image with my 40D that's more than a fraction of a stop off, exposure-wise (the same was true of my 20D). I've come to trust Evaluative metering.

I'm using a 20D, with a 40D due to arrive Wednesday.

I somehow have the feeling that I would like to use evaluative metering, with the camera free to place metering emphasis (what ever that means) on the areas around all "active" AF points, with the camera choosing those points (as if automatic AF point selection were in effect), but nevertheless for actual focusing purposes have a single AF point preordained.

Do you know any way to make a 20D and/or 40D do that for me?

One might think that (on the 20D) one of the options for CF04 might lead to that, but it doesn't seem to come out that way.