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Originally Posted by amitk26 Are you sure that 350D tracks the focus ? From what I know the shutter snaps in Servo AF on 1000D but if subject is moved the picture will be blurred in 350D and 1000D.
With Digic4 canon introduced tracking the focus called servo AE. googled on Servo AE and found the explanation of the feature in context of P&S. Canon UK - Power, flexibility and stand-out style ? capture everything with the stunning new PowerShot SX210 IS
Please check if the manual says Servo AF with mention of for focus tracking or just Servo AF.
50D and 500D have same processor ( Digic4) but burst rate differs. I think either it is artificially locked in software or there is some other bottleneck like slower CPU and bus clock , both XXD and XXXD uses same RAM as well.
The difference between 50D and 500D is in shutter mechanism 1/4000 max for 500D versus 1/8000 for 50D.
As per the information available in public domain the Focus tracking mechanism is feature of the Digic 4 processor of Canon. Also they have built face detection / motion detection in P&S range based on this capability. |
Well the 1000D and 350D specs do say AI Servo AF, which basically means focus tracking. They also give maximum speed
Of course 450D AF module can focus faster.
As for limiting shutter speed, it also depends on the mechanical shutter, and there is obviously some limiting done in software, as well as buffer etc.,
As for face detection, again you are confusing. Servo AF means continuously varying the focus when subject where the center point rests. so lets say you have a car coming towards you, in one shot AF, you half press camera locks focus, and when you full press, the camera takes a picture, It is possible, that due to car moving, it will be out of focus. In AI servo, the camera is continuously focusing under the center point.
So even if you are moving the camera, its continuously focusing. It drains batteries though as AF mechanism is always active, not just on half press.
Now coming to face detection, I think I understand where your confusion is coming from.
There are two ways to focus in a DSLR with live view. You either use the focus points, which is phase detect. So if you are shooting a moving dog, as long as you keep the dog in the focus point of your choice, it will be in focus, but if the dog is not under the focus point of your choice, it won't be in focus.
With live view you have the choice of "Contrast detect" focus. Its slower, but its used in "tracking" which almost all current P&S have.
For example, my FZ35 remembers what I look like. when in potrait mode, somebody shoots a group photo, it recognizes the faces, and if I move around, the camera will move focus accordingly.
Now the fixed AF points cannot be moved around, but in contrast detect focus this is possible.
Now coming to action photography, no pro uses contrast detect due to its inherent slowness over phase detect AF. They move the camera with the subject always looking through the viewfinder and keeping center focus point on subject.
Example a photog shooting a footballer running. The camera continuously auto-focuses on the footballer, as soon as he is about kick, the pro will press his shutter button, and let loose 20 shots in 2 seconds.
In most scenarios when shooting a fast game, around 15-17 of these shots will be in focus
For the newspaper print, the photographer will use the best out of these.