Canon 40D Burst Rate in AI Servo

Doesn't explain wny with the grip but is your answer here...https://photography-on-the.net …/showthread.php​?t=1157763

What brand grip by the way?

Which lens are you using? Any of the old Arc-Form Drive lenses will really slow down in AI Servo. Some other lenses may have the same problem.

It's a 400 prime. I'm guessing unfortunately I may have to sacred if the grip?

Thanks for all the kept
Harry

As some have already hinted above, when using the camera in Servo AF, the camera updates the focus setting between each frame.
The best cameras can do this under good conditions without sacrificing any drive speed. But even a 1DX will slow down, when the conditions aren't favorable.
Dim light, low contrast, slow AF drive motor in the lens - any of these characteristics will influence Servo AF focus update time, and thus also continuous drive speed.

The 40D doesn't have any settings where you can optimize the performance of Servo AF to suit your particular needs. In the APS-C range, that came first with the 7D.

Take a white piece of paper, draw a solid black line on it. Place the paper in sunlight, aim the center AF point at the line and fire away. If the camera can't maintain full drive speed with Servo AF on such a target, then something is wrong. But if the camera slows down when trying to track a bird in fligh, deer running in dim woods or whatever in various real world conditions, then you've just hit the limit of the performance you get from a 40D.

The 7D has a separate CPU dedicated to AF calculations, but still you can hear the continuous drive speed drop a bit from the max eight frames/s, when using Servo AF on less than optimal targets.

Thanks, just tried that. AI Servo was working at full burst without th grip, but then when I put the grip in it slowed down again. Guessing it's just a faulty grip?

You are using the camera's batteries in the grip, are you? Not AA batteries?

Yes I am using the canon batteries
Harry

Then I have no real explanation. Is it a genuine Canon battery grip too? I've not experienced any drive rate degradation when using my 40D with the Canon BG-E2N grip.
Using AA batteries in the grip slows the camera down, though.

Yes it is. Oh well I will just have to not use the battery grip when I need the higher burst rate.
Shame tere is nothing I can do, thanks to l for the input it is muchly appreciate

Harry

Before you give up, did you try using a pencil erasure to clean all the contacts? Batteries, inside grip where batteries go, grip that goes into camera, and contact inside camera? It can't hurt, and its free.

Does it matter if you use the trigger button on the camera or on the grip?

We'll I have conducted a few more tests this evening:
On MF and one shot without the battery Grip I am getting 6.5 fps
On AI Focus and Servo on a black line on white paper, with no battery grip I get about 4.5.
With the battery grip in I get about 3.

I am starting to worry about the camera because I know the 400prime is supposed to have brilliant af?

Harry

eh? how come youre not getting urrmmm one shot?

Let's take AI focus out of the equation, since it's just an attempt to automate the switch between One Shot AF and Servo AF.
The AF capability of the lens shouldn't be any issue when doing the test with a black line on white paper, since then there's no focus distance change to handle. That's why I suggested it - it put's no heavy load on neither the Servo AF algorithm nor the execution of the focus setting.

Weird, this. Come over here and we'll compare with my 40D. I still have it.

soccersnaps wrote in post #16641198
eh? how come youre not getting urrmmm one shot?

One Shot is a Focus mode. It is not the same as Single Shot frame advance or Drive mode.

The name is however somewhat misleading and confusing.