Questions about EF 50 f/1.4

Hello everyone,

I just bought a 50mm 1.4 for my XTi, and while it seems to be a great little lens, I'm wondering if the AF of my copy does operate properly.

Indeed, at relatively close distances (3 to 5 feet), the AF seems to hesitate between two positions when it stops rotating.

Every time I half-depress the shutter, the AF is slightly moving, even if the camera did not move nor the focus point. It seems that the motor is not able to stop precisely on the right position.

Is it related to the slight mechanical looseness of the front barrel (which is moving while focusing) ? Did you observe that on your copies ?

Thanks for your replies!

Is your camera set to single shot autofocus or AI Servo?

michaelgreen78 wrote in post #5597069
Is your camera set to single shot autofocus or AI Servo?

I'm having similar issues with my 50mm 1.8, and mine is set to Autofocus. Any way you could explain the difference between servo and single shot, and why problems occur??

michaelgreen78 wrote in post #5597069
Is your camera set to single shot autofocus or AI Servo?

I'm using One Shot AF mode, with the center focus point only.

I don't think you have much to worry about to be honest, as long as the photographs come out sharp. My lenses do a similar thing. When you depress the shutter button half-way you are effectively asking your camera to search for focus which is why it moves. If you are happy with the focus you have and won't be moving the camera between shots then set it to manual focus.

You could be just on the verge of the lens' minimum focus distance and the lens is struggling to focus.

Anke wrote in post #5597237
You could be just on the verge of the lens' minimum focus distance and the lens is struggling to focus.

Unless your camera is on a tripod with a stationery object, the lens would adjust. Sharp pictures will be the true test. I agree with Anke that you may be very close to the minimum distance.

My 50/1.4 behaves like that too, thought it has to be closer still, like almost to the end of its close focusing range.

Same here! Nothing to worry about, they all seem to do it.

My Sigma 30mm acts similarly when at f/1.4; even the slightest movement causes it to refocus slightly. What I find more annoying when when I'm near the minimum focus distance and the damn thing hunts all over before giving up.