Fisheye/Wide Angle Lens Recommendation

Im currently looking to get a ultra wide angle/fisheye lens for my kit. what im wanting it for is sports photography mainly hockey as I want to put in in the back of the goal and also racing photography for pit shots.

I need a somewhat wide aperture something like 2.8/3.5 ish and I will be using it on either my 1d mkIII or 50d

It's not clear whether you're thinking ice hockey or field hockey - but I'll assume it's the former.

The fast 15 mm and 16 mm varieties offer about 180 degrees diagonal on a full frame image. If you're using and APS-H camera, the diagonal is 33.3 mm and you're limited to about 135 degrees. You can increase this by using the 8-15 /4L zoomed to 11 mm. This achieves a 180 degree diagonal and about 155 degree coverage from edge to edge. The lens glare shield can stay on - but it's pretty ineffective so you can take it off too.

Some caveats - Firstly, wide open, this lens can only do f/4. Secondly, it has a bulbous front element and is quite vulnerable. Third, the lens feels fragile. I'd be concerned about a puck hitting it at 90 mph. - so some sort of protective enclosure could be a good idea....

An alternative - well maybe a Rokinon 14/2.8 - it's a lot less expensive than the zoom and you gain a stop but you'll not be covering the same field. Depending on your budget, you may decide to skip the enclosure.

I love my 8-15mm f/4 fisheye. I know it's an f/4, but the zoom makes it worth it in my eyes. Besides, the capabilities on an APS-C or H sensor are much better than on FF, since it acts a full-frame fisheye from about 10-15mm on APS-C and 12-15mm on APS-H.

I've had the 15mm f/2.8 full-frame fisheye and was happy with it, but it lacked the contrast and wow factor I get with the 8-15mm. I've not used it much on the 8mm circular setting (only on FF sensors), but I just need to get used to that effect. I am much more comfortable with a traditional rectangular image, but the effects are really cool.