Unsharp mask/Post sharpening

I shoot on a Canon T3i with the sharpness set to zero. Does anyone have any suggestions on how to sharpen in post in FCPX? There's no unsharp mask and when I use the sharpening effect I get a halo around the edges.
Thanks!!

Sharpening can be tricky, also with an Unsharp Mask filter. If you are going to need this on a regular basis I think it pays off to get a specialized plugin to do this kind of work.

I have achieved really decent results with the video noise reduction plugins from Magic Bullet and Neat video. Unfortunately neither MB or Neat have updated their plugins for FCPX yet. But they are working hard to get there, so we may expect them soon. However, the Neat filter already works with Motion 5. If you have Motion 5 alongside FCPX I would advise you to check the plugin here:

www.neatvideo.com/

Oh yes I nearly forgot: if you do have Motion 5, this has an Unsharp Mask filter.

If you don't have Motion you also might check the Coremelt plugin package which has recently been updated for FCPX. Besides some really cool effects filters the CM package also has a Noise Limiter filter that does e decent job. I haven't updated my CM plugs for FCPX yet but I have used them extensively in FCP7 and Motion and they are a great value for their money.

Another great package is FxFactory Pro. This package includes a Noise reduction filter as well as 5 Sharpen filters and it works in FCPX.

CoreMelt Pigment also has a "Purple Frindge Reduction" filter that may help also.

I'd also recommend the modestly priced Mlooks (and mlooks2), grading presets for FCP X, built in Motion, which include some presets (such as "Sharp") that apply adjustable sharpening as part of the effect. For Conduit users, my toolset has luma sharpening and edge enhancement.

Thanks for the good tips!
I appreciate them!