Well, I stumbled across this whilst looking for a different lens. When I saw the price my first thought was that this will be the usual cheap junk you'd find on eBay or similar. However I looked at the reviews and they are mostly positive and I was then sold on the idea of trying fisheye (a dedicated lens is a lot of money just to experiment with!), a bonus was that it also has a macro lens too.
Well built - All metal construction, very sturdy.
Fisheye and macro in one unit.
Cheap - Affordable if you want to try fisheye.
Comes with nice carry case and lens cloth.
67mm Front filter ring.
Dust Magnet - Lens attracts a LOT of dust.
AF doesn't work accurately/at all.
Front lens cap fits very poorly.
How to use:
To use as a Fisheye lens; Screw the macro lens to the fisheye lens, screw the appropriate adapter ring to your camera lens, then screw the Opteka lens to your camera lens.
To use as a macro lens; Simply unscrew the fisheye lens from the macro lens. (Max distance is around 2" with canon kit lens).
Initially I unpacked this and screwed the 58-52mm adapter (included) to my 55-250mm lens, screwed the macro and fisheye lens on and went "meh". Using this lens on a my 55-250mm doesn't produce a fisheye effect, all it does is widen the view to ~24mm equivalent, from 55mm on the image becomes VERY soft. The macro works but only really at 55mm, there after the edge again become increasingly soft.
I then tried the Opteka on my kit 18-55, better results, at 18mm you get the typical fisheye effect, at ~38mm the vignette isn't visible, but the fisheye effect become more like lens distortion than anything. You can focus objects as close as 1mm from the lens, any closer and you'll find yourself focusing on any dust on the lens! The macro lens is good when attached to the kit lens, at 55mm you can really get some impressive photos, for example seeing the fibres in a bit of paper.
All in all, for the money you cant really complain! With the Canon EF 8-15mm f/4L Fisheye Zoom Lens costing nearly £1000.00, the Opteka .35x HD² Fisheye Macro is a no brainer for anyone wanting to experiment with fisheye and macro without shelling out mega bucks.