Tokina 17mm AT-X pro

I just bought this lens based on the good reviews and it seems to have a problem when I engage the clutch to manually focus while on af. It makes a screeching sound and you can feel a little stiffness in a couple of spots as you rotate it. It seems that it needs a little oil on some gears. Does this clutch system have any real benefits over just using the af or manually focusing? Even though I have only had it a very short time I am thinking of selling it since I don't seem to get into the ultra wide angle type of photography. I would of course disclose the problem to all buyers. Anyone here use this lens and have opinions on it?

I've owned one- not a bad little lens. The screeching you're describing is not normal. Sounds like yours needs a CLA (clean, lube, and adjustment).

I have the earlier version, same optics but with af on/off switch and without the shift ring clutch. It is not bad at all, substantially sharper in the corners than 17-40 at mid apertures, strong CA issues that are correctable, fairly moderate but moustache distortion, not a factor for landscape, and fairly flare resistant, as is the 17-40. I am liking it. For the time being at least, it has bumped the 17-40 to the shelf, with help from the ZE21. Nice and compact and light. For the price they go for, they are a bargain if they fill a need not better fulfilled by the convenience of a zoom, or the image quality of a much more expensive (and large and heavy) lens.