Keep AI Servo on when shooting at thin DOF?

I am experimenting setting the focusing mod = AI servo (continous tracking with shutter half pressed) when shooting at thin DOF (50 f2.2). Just wondering if anyone can think of any drawbacks to this approach.

My 50 f/1.4 rattles a lot when on AI Servo, even on still subject, the focus being so-so. It's nothing like the 200 f/2.8L, wich stops movement once focus is achieved.

kenwood33 wrote in post #3990788
I am experimenting setting the focusing mod = AI servo (continous tracking with shutter half pressed) when shooting at thin DOF (50 f2.2). Just wondering if anyone can think of any drawbacks to this approach.

Are you shooting a moving subject or a still one. If the subject is still, then you should use OneShot AF mode. You'll have less tendencies for the the subject to go out of focus that way. If the subject is moving, then by all means, use AIServo.

The subject (people) is/are not purposefully moving, but because of the thin DOF, any slight movements back/up may result in blurry picture. The reason I am shooting at f2 or wider is because of the low light condition.

I usually shoot with 1/focal length of lens or faster. I do notice the 50 1.4 rattles quite a bit when I kept my finger half pressed on the shutter. I tested it using still objects and the result is acceptable. I am going to try it out with people as subjects.

Using AI servo on stationary objects will result in the focus changing as it is looking for moving objects. Try this by locking focus on a stationary object with AI Servo and snap off a burst of images. You'll see the AI Servo hunt for the moving object, making most of your burst of images OOF.

Hogloff wrote in post #3990969
Using AI servo on stationary objects will result in the focus changing as it is looking for moving objects. Try this by locking focus on a stationary object with AI Servo and snap off a burst of images. You'll see the AI Servo hunt for the moving object, making most of your burst of images OOF.

I see that is logical - but - I have been adviced to always use A1servo when using the 70-200 ? even on subjects not moving -- hmm - scratching my head..

Nilsen wrote in post #3991465
I see that is logical - but - I have been adviced to always use A1servo when using the 70-200 ? even on subjects not moving -- hmm - scratching my head..

So, what makes the 70-200 different from any other lens, I wonder?

PacAce wrote in post #3991556
So, what makes the 70-200 different from any other lens, I wonder?

dont know - got the advice in this forum

Nilsen wrote in post #3991581
dont know - got the advice in this forum

Just goes to show, it doesn't hurt to get a second opinion sometimes, even in this forum.