Revisiting this topic, I decided to purchase a used 3x Wide Angle lens for my XL2 (mostly because I am getting tired of taping the Aspheron on to my lens). For the sake of doing it, I decided to compare the 4 lens combinations at my disposal:
-Stock 20x XL2 lens
-20x + Aspheron
-3x Wide Angle
-3x Wide Angle + Aspheron

The 20x + Aspheron is a slightly wider image than just the 3x alone. I see no barrel distortion or vingetting (using DV Rack on underscan to check this). It zooms in about 6x or 7x (estimate) before suddenly popping out of focus. I do notice that it tends to focus on dust particles on the lens, so you have to keep this thing VERY clean.

With the 3x alone I see no distortion or vingetting (obviously), zoom is limited to 3x (again, obviously), but I find myself having an easier time achieving critical focus with this lens than I do with the 20x + Aspheron.

The 3x + Aspheron is CRAZY. At this point there is plenty of barrel distortion; pretty much a fisheye lens effect. I noticed a bit of vingetting on the top left corner. Achieving focus with this combination is a nightmare, but it's possible and the resulting image is superwide fun.

After all is said and done, the 3x makes life a lot easier since I don't have to worry about taping anything together, but I like the look of the aspheron more.

Interesting!

So the 3x Canon when used with the Aspheron gives oodles of barrel distortion? Well I'm blowed. Now why should that be? The Canon is 3.4 mm to 10.2 mm. My Z1 starts at 4.5 mm - not hugely different, and yet the Aspheron works beautifully with that, curing the Zeiss's inherrent barreling.

As regards focusing on the dust this has nothing to do with the Aspheron as such - and all to do with the focal length and therefore the dof. When you're shooting at focal lengths below about 4 mm you really need to keep the aperture wide - f/2.8 or wider.

The Aspheron on the 20x means you have a 2.86 mm to 17.mm or so - surely more versatile than the 3x on its own?

tom.

Here are some photos to illustrate. What I consider to be a lot of barrel distortion, some may find more tolerable.

3x Wide Angle:
http://i39.photobucket.com/albums/e158/hectma/Lens03-3x-wide.jpg

3x + Aspheron
http://i39.photobucket.com/albums/e158/hectma/Lens04-3x-wide_aspheron.jpg

20x XL2 Stock Lens
http://i39.photobucket.com/albums/e158/hectma/Lens01-20x.jpg

20x + Aspheron
http://i39.photobucket.com/albums/e158/hectma/Lens02-20x_aspheron.jpg

I didn't use a tripod, so the composition changed a little...but you can get a rough idea of the difference between each lens option. (sorry about the messy room)

Just going by the numbers, the Aspheron should be more versitile being slightly wider and having a greater zoom range...but in terms of use I'm finding the 3x to be easier. This might change if I had a real adapter made for the aspheron rather than having to tape it to my lens.

Moderator note: this thread was split from a discussion about wide angle lenses for the Sony Z1 (http://www.dvinfo.net/conf/showthread.php?p=525612)

Chris - you said in an earlier post that the 3x zoom + the Aspheron gave you 'fisheye-like barrel distortion'. As I suspected I see no evidence of that at all in your shot. Mind you (grin) your choice of subject makes for difficult scientific evaluation. Get outside lad and take some shots of a building as here:

http://www.fortvir.net/gallery/v/tom-s-photo-album/

I agree - without a proper screw on adapter the Aspheron is just too vulnerable to use out in the field. Thanks for sharing the info though.

tom.