Downsides to the Tokina 10-17FE

I'm considering the Tokina 10-17FE now. With so much admiration it seems for the 10-17FE, could I have some input on what anyone dislikes about it?

It has slightly more CA than Nikon's 10.5, but it is hardly noticeable. I think it is a good choice and I would go for it if I didn't have a 10.5.

Same here, if not for the fact I have the 10.5 already i would buy the Tokina in an instant.

I believe the Tokina doesn't have a filter slot in the rear, not a reason for not getting it, but I shoot a lot with the magic filter and it will requires more artisanal way (read : tape) of holding the gel in place.

I have a 10.5 collecting dust on the shelf, and haven't mounted another wide angle lens to my camera in the past 7 months...

As a Canon user, you don't have this focal length available in another option, so there is no downside.

I believe the Tokina doesn't have a filter slot in the rear, not a reason for not getting it, but I shoot a lot with the magic filter and it will requires more artisanal way (read : tape) of holding the gel in place.

It's doesn't have it but in the Nikon version it’s possible to mount the filter with some sellotape.

Like all tools of course there are downsides. It just depends on the application.

If you shoot Canon and you need a full fisheye view there are no other options for 180 degrees wide. In this case there are no downsides.

If you don't need full fisheye view there are other options. A full frame fisheye is difficult to light underwater because its so wide. Its difficult to find subjects that are comfortable enough with you being close enough for them to take a significant portion of the frame. Its difficult to keep your fins and other divers out of the frame too. The zoom is nice because it allows you the flexibility to tune it to whatever view you want, even if you decide to leave it there. You may find that the 10mm is more than you need--I think 15mm is just about perfect. Also with a cropped sensor, less than 10mm also means the photos look a little less fishy than a full 180 degree view.

OTOH I don't feel that I need a zoom underwater--I can frame faster with my fins and UW I'm fully task loaded anyway. And the downside is a slower aperture and more CA. If you don't think you need the full view of 10mm I find the Sigma 15mm FE to be a better option. Its in the sweet-spot. It allows Magic filters which simplifies lighting and the faster 2.8 aperture allows better AF when you cut the light with a filter. Finally, with Nikon and Canon now making FF sensors FF is only a matter of time. The Sigma 15mm is "future proof" since its a FF lens.

That said, if you want one WA lens to handle all conditions on a DX sensor camera, the 10-17 is probably the best bet out there.