How important is it that the Canon 50mm f/1.4 lens does not return distance data?

Question

I read at the photonotes website that the Canon 50mm f/1.4 USM lens does not return distance information to the camera, to be used for E-TTL II.

How important is this, and should this be a determining factor when purchasing a lens?

The reasoning behind distance information is somewhat vague and stated as:

Under certain conditions the distance data is factored into the calculations for determining proper flash output.

Answer 1

I can't see it being important, no. Distance information might make flash metering more reliable, but it's not essential. However you have to ask why you'd be using a fast prime lens with direct flash in the first place. A wide aperture is useful when bouncing flash due to the loss in power, however when firing the flash directly you don't need the speed and so a zoom would be more useful. But the real advantage of an f/1.4 lens is the ability to shoot indoors without flash

Answer 2

No, it is not important. The 50/1.4 lens does just fine with flash.

That said, it's the only lens I have that I would not buy again. I've had trouble occasionally with it deciding not to autofocus. Apparently, that's a design flaw with this particular model. I no longer use it on gigs because I don't trust it.