because the rebel doesn't really have spot metering and that contributes to the lack of tones that it can recognise; here's a photo I made today (thinking of this thread, but also wanting to photograph my new toy)
Canon EOS 5D ,Tamron SP AF 28-75mm f/2.8 XR Di LD (IF)
1/60s f/2.8 at 75.0mm iso320
I spot metered the grey knob on the ballhead so that all the other tones would fall into place. With the 300D, the best you can do is to switch to manual mode and use the center weighted average metering to read your scene and then adjust your settings as you wish to render your tones. The 300D also has partial metering, but it only kicks in when you press the AE lock on your camera after you half press the shutter button. (see page 84 of your manual) In backlit situations such as I used with the above subject, you may want to select shutter priority in order to have control of your aperture without a convoluted messing around with the exposure compensatiun button. By selecting your shutter speed you can at least be sure that your photo will be in focus and lessen camera shake; no need to select shutter priority if you put the camera on a tripod and don't need to worry about camera shake.
Here's a photo of the same subject with the same lens made with the 300D in shutter priority mode and AE lock button activated to get the partial metering activeated
Canon EOS 300D Digital Rebel
1/80s f/2.8 at 75.0mm iso400
The photo has less tonality than the photo made with the 5D which has spot metering. It's also affected by the 1.6FOV crop which contributes to pixel pitch, DOF, etc.