7D Autofocus

Quick question. They say the 7D has an updated AF system and works very well at 8fps, does this mean it focuses between each picture? Sorry if this is an obvious answer.

canon_fanatic wrote in post #8674775
Quick question. They say the 7D has an updated AF system and works very well at 8fps, does this mean it focuses between each picture? Sorry if this is an obvious answer.

Yes.
Rob.

Not necessarily. As I understand it if you're in 'one shot' AF it will only lock focus once and if you're in AI Servo the AF system will constantly monitor the subject and adjust focus as and when it detects movement - not necessarily locking focus between frames.

gofer wrote in post #8674821
Not necessarily. As I understand it if you're in 'one shot' AF it will only lock focus once and if you're in AI Servo the AF system will constantly monitor the subject and adjust focus as and when it detects movement - not necessarily locking focus between frames.

I hope it's gonna be fast enough for my surfing

For sports/action, it's best to use back button focus to separate the focusing from the shooting. That way, you can track before and during your sequence.

The Moose wrote in post #8674962
For sports/action, it's best to use back button focus to separate the focusing from the shooting. That way, you can track before and during your sequence.

What is "use back button focus to separate focusing from the shooting". I think I know what you're talking about but please elaborate.

scslmd wrote in post #8675026
What is "use back button focus to separate focusing from the shooting". I think I know what you're talking about but please elaborate.

Back button focus is when you change Custom Function #4 to AE lock/AF. It changes the * button on the back of the camera to focus and a half-press of the shutter button to lock the exposure. It takes a bit of getting used to but it's much better for following and tracking moving objects while shooting sports.

The Canon AF system works in between exposures.

At this point we don't know if the 7D will have improved AF or not .. all we have is Canon's marketing fluff and a few early (selected by Canon) testers. The camera has yet to be in the hands of real world shooters.

If Canon really wanted to give us an improved AF system for their consumer bodies they would simply use their 8 year old technology from the discontinued 1D body. Instead we get a lot of Digic nonsense. So I've seen these "improved AF" claims before.

Can the 7D AF keep up at 8 fps? .. based on ALL other previous Canon consumer crop bodies starting with the 10D the fps runs faster than the AF can keep up .. which simply means you have more out of focus pictures taken more quickly.

Will the 7D be any different?
Probably not.

I would not say it's impossible in 8 years for them to have discovered a way to as well yet more cheaply than the 1D.

But I agree...at this point we don't really know if the 7D scores a hit.

I would also mention for the sake of the OP that Canon and other companies use some algorithm of "predictive focusing" for action shooting. The system measures distance to the subject between frames, notes the change between views, and attempts to extrapolate the changed distance for the next frame. It will actually attempt to "lead" the subject.

That's why it's necessary to begin autofocusing on a moving subject for a half second or so before you actually begin shooting.

mmahoney wrote in post #8675076
The Canon AF system works in between exposures.

At this point we don't know if the 7D will have improved AF or not .. all we have is Canon's marketing fluff and a few early (selected by Canon) testers. The camera has yet to be in the hands of real world shooters.

If Canon really wanted to give us an improved AF system for their consumer bodies they would simply use their 8 year old technology from the discontinued 1D body. Instead we get a lot of Digic nonsense. So I've seen these "improved AF" claims before.

Can the 7D AF keep up at 8 fps? .. based on ALL other previous Canon consumer crop bodies starting with the 10D the fps runs faster than the AF can keep up .. which simply means you have more out of focus pictures taken more quickly.

Will the 7D be any different?
Probably not.

I also agree, the Jury is still out on the 7D, I hope for Canon's sake its better than the 50D. I use it strickly as a back up to my (how many year old 1D MK II?). The MK II is far superior in focusing accuracy in AI-Servo at 8 FPS.

mmahoney wrote in post #8675076
If Canon really wanted to give us an improved AF system for their consumer bodies they would simply use their 8 year old technology from the discontinued 1D body. Instead we get a lot of Digic nonsense.

Eh? Are you talking about the 7D having two Digic IV processors? But they are there to be able to transfer and handle all the image data from the 18 Mpixel sensor when shooting at eight frames/second.

Just like the 1D Mark III, the 7D has a dedicated AF processor, separate from the main sequence controller and the image processors.

Fact is, that in theory, the 7D is the best camera so far from Canon, as far as AF goes. In theory, and by that I mean when reading the specifications. It's lacking virtually nothing from the 1D Mark III, the main exception being 45 separate AF points, but has all or more of the other goodies the 1D Mark III can show.

Besides, you have to use lenses with max opening of f/2.8 or better on a 1D Mark III to get 64 focusing elements (45 linear normal precision + 19 linear high precision), where the 7D already at f/5.6 has 38 focusing elements (19 cross-type AF points). The difference between 38 and 45 isn't dramatic, and it's perhaps likely to assume that owners of a 7D more often have lenses slower than f/2.8 than a 1D Mark III user has. Perhaps.

Finally, Canon claims that they investigated using a larger AF module for the 7D (read: With at least 52 AF points, as some main competitor has 51), but found out that such large AF sensors are too sensitive to dimension changes due to temperature changes. So they went back to 19 points in the area used by the nine points in a 50D, however with ten more points in between, to better handle AF point handover when using Servo AF.

Once again, I agree that all this is in theory. Reasonably, it's at least better than my 40D, but by how much remains to be seen.

Dean Humphrey wrote in post #8676224
I also agree, the Jury is still out on the 7D, I hope for Canon's sake its better than the 50D. I use it strickly as a back up to my (how many year old 1D MK II?). The MK II is far superior in focusing accuracy in AI-Servo at 8 FPS.

It's a 1-series .. It's supposed to be superior...

Look in the manual on line at Canon. You have options with AF in servo mode to set priority to either shutter release, or achieving focus lock. If the latter, it will lock focus on each frame before shutter release. If the former, it will use the AF predictive calculations and release the shutter using the calculated AF point based on the movement and acceleration of the subject.

We will know soon enough, but what Canon is telling us, is the 7D has some AF features the same as the MkIII, some aspects better, and some aspects not better.

How this combines we will need to judge in our hands,. but it looks like it is very possible it could out perform the mkIII...
It should certainly dust up any other Canon body that does not have a 1 in front.

....and that "some aspects not better " part?
That's what they will save for the MkIV

You'll know how good it is or isn't when you see the pros using them at the winter Olympics or NFL games- or by its absence.

Gene