Looking at the 2 links, the second is classed as a fish eye, not a wide angle lens. This means that on a standard lens, you will get something like a circular picture e.g. straight lines will 'bend' and become distorted. You get cool effects from these, close up big nosed facial shots for instance but for wide angle - no good sorry.
The discussion above that was going on for a 'standard lens'. in 35mm the standard photograpers lens, sometimes called the workhorse lens has been a 50mm lens either f1.8 or f1.4 although if you had mega bucks ymmou has a f1.0 :shock: , although Pentax on the old M series mount did a 40 + 45mm standard lens :? (40mm being a 'pancake' lens)
With all screw in lenses there will be a drop in optical quality so use small apertures as the image quality on the edges will not be sharp. Also these are normally on size so you may need a step ring adaptor for use with your camera. P.S. The prices are OTT, try Jessops new or S/H or try Ebay
If I was you I'd get the real deal, they're not expensive anymore - what camera are you using :?:
