Center Focus Point in Different Canon Models

[ElCapitan]

I know that certain cameras have more or fewer focus points than others (5D vs 7D), but is the overall auto focus better in certain models over others?

I am using a 5D for sports using the center auto focus point. I know the 5D only has 9 auto focus points which is lacking compared to the 7D's 19, or the 1 series far far more AF points, but what if you are only using the center point?

My questions is, is the AF in the 7D going to be better on the center point compared to the 5D's center point? I am thinking about buying a 7D for sports and wildlife and using my 5D for landscapes and portraiture, but if the center point offers the exact same AF, then I may hold off.

[dlambert]

Both cameras have a cross-type point in the center, but in the 7D, all the rest are cross-type, too. Additionally, there are some pretty cool autofocus options that I believe are new in the 7D:

Canon EOS 7D Review: 3. What's new: Digital Photography Review

My guess is that if you're really able to keep the center point on your subject all the time, you'd see only a minor improvement by going to the 7D. Features like AF point expansion and AF zones, though, look like exactly the sort of features that would help get the right focus point selected quickly when your subject is moving around.

[ElCapitan]

Thanks for the response. I figured the center points would be mostly the same. I suppose my main problems are just shooting in poor lighting and that the 5D is going to have a shallower DOF than a 7D would, even at 2.8. I could go down a stop or 2, but not sure if I want to be shooting at 6400 ISO to get an acceptable shutter speed.

[inkista]

Originally Posted by ElCapitan

...I know the 5D only has 9 auto focus points which is lacking compared to the 7D's 19, ...

Only 9 selectable AF points. There are actually 15 AF points. And while there's only the single cross type, there are three high-precision sensors (with f/2.8 lenses).



On the 7D only the center point is high-precision w/f/2.8.

In essence, the 5D Mark II's AF system is more designed to be used with f/2.8 or faster lenses, while the 7D's is designed for use with slower lenses. Cross-type sensors are "better" because they have twice the area and therefore twice the possibility of finding contrast to detect. But f/2.8 sensors are better in terms of accuracy with faster lenses, because they're capable of using a larger f/2.8 baseline rather than the standard, smaller f/5.6 baseline. Nobody's quite sure how the "high-precision" extra boost to accuracy happens, though, since Canon's kept that under wraps.

...but what if you are only using the center point?

My questions is, is the AF in the 7D going to be better on the center point compared to the 5D's center point? ...

My guess would be it's pretty even. Both have the same center-point sensor: cross-type, high-precision f/2.8. But then, that's the point of the 7D: to make it much easier to use all the other AF points.

[ElCapitan]

Originally Posted by inkista

Only 9 selectable AF points. There are actually 15 AF points. And while there's only the single cross type, there are three high-precision sensors (with f/2.8 lenses).



On the 7D only the center point is high-precision w/f/2.8.

In essence, the 5D Mark II's AF system is more designed to be used with f/2.8 or faster lenses, while the 7D's is designed for use with slower lenses. Cross-type sensors are "better" because they have twice the area and therefore twice the possibility of finding contrast to detect. But f/2.8 sensors are better in terms of accuracy with faster lenses, because they're capable of using a larger f/2.8 baseline rather than the standard, smaller f/5.6 baseline. Nobody's quite sure how the "high-precision" extra boost to accuracy happens, though, since Canon's kept that under wraps.


My guess would be it's pretty even. Both have the same center-point sensor: cross-type, high-precision f/2.8. But then, that's the point of the 7D: to make it much easier to use all the other AF points.

Thanks for clarifying. I would love to get a 7D, especially with the supposed $200 rebate coming Feb 20, but I think I am going to hold off for now. Overall I am real happy with the 5D, and only have a small amount of throw away shots due to back focusing. I just need to find a better sitting/kneeling position under the net to react faster.

[inkista]

I've said it before, I'll say it again: Canon Loyalty Program. Last I heard, a factory refurb 7D body is just a hair under $1100 on the CLP. It's how I got my 5DmII for $1800.