In my recent post regarding dSLRs I talked about the Canon 300D / Digital Rebel and its forced metering and focusing modes. After more research I’d like to clear it up for you a bit.
First, it’s important to mention what a focus modes and metering modes are.
A focus mode is HOW the camera AUTO focuses. There are really, today, three types. First, there is OneShot. This means the camera focuses and stays there. Then there is AI Servo. This means the camera focuses and then constantly adjusts the focus on that object using programmed intelligence keeping the object in focus as it moves. Finally, the is AI Focus. This is basically a combination of the two. It starts off in OneShot. Then, if it senses movement, it switches to AI Servo until the object stops moving.
A metering mode is how the camera AUTO meters. Again, there are three basic types. Evaluative/Matrix, Center-Weighted, and Spot/Partial. Evaluative metering is when the camera looks at many different aspects of the image including distance, light intensity in many different regions, overall light intensity, etc. It takes all of these pieces of data and compares it against a "database" of known exposure data to determine exactly how the image should be exposed. This is most camera’s AUTO mode. Center-Weighted metering is when the average intensity of light is used to determine exposure. It’s called Center-Weighted because the center of the image generally accounts for more of the calculation (usually 60%) than the rest of the image (which is usally 40%). Spot or Partial metering is when the light intensity of a very small area in the center of the camera is used. This is generally for advanced use.
The 300D has many shooting modes broke into two categories: Basic and Creative. In the Creative category you have your standards: Aperature Priority, Shutter Priority, Manual and one additional called AI-DEP which is where the camera chooses aperature based on a calculation to ensure that all the objects in the focus points will be sharp. The Basic modes are things like Night, Sports, Portrait, Macro, Outdoors, etc. There is also an AUTO mode which does everything for you.
Here’s how the camera works. The metering mode and AI Focus mode cannot be changed. They are linked to the shooting modes mentioned above. The metering mode is Evaluative for ALL modes except Manual, which is set to Center-Weighted. Additionally, with the press of a button, all the Creative modes can be changed to Partial or Spot metering mode. The focusing mode is AI Focus for ALL creative modes as well as Auto mode. The focusing mode is OneShot for ALL the basic modes except Sports, which is linked to AI Servo. In ALL cases, manual focus is possible.
Now, with that being said, most users who would use Center-Weighted metering will most likely prefer Manual mode anyway. They may also prefer some of the other Creative modes, but certainly not any of the Basic modes. And, with the available Spot meter (which is much more useful than Center-Weighted, in my opinion) in all Creative modes, this shouldn’t be a problem. As far as the focus goes, AI Focus should be pretty good in all situations where a user would want Auto Focus. It may be a bit slow for the sports photographers, as it doesn’t jump straight into AI Servo mode. But, in many cases, a sports photographer is likely to use Evaluative metering anyway, so they may as well go ahead and choose the "Sports" basic mode. Being forced into OneShot mode in most of the other Basic settings should also not be much of a problem as, as long as the user is using those settings for what they intended, the focus mode is the most correct anyway. The only possible problem is in manual mode. In many cases, manual mode users would prefer the OneShot focus mode. Whether AI Focus is capable of keeping it in that mode to my liking can only be determined with use. Nothing, however, is more annoying that having the auto focus move on you, simply because you recomposed the shot.
Taking all of that into consideration, looking at image comparisons, lens prices, and the state of the market currently, the Canon 300D may very well be my next camera.
We’ll see.