thank u all for the kind replies. yeah i should have done more research before buying. main thing was i saw how my friend used it on her kit lens and thought it was quite cool, and then decided it should work on my 50mm.
btw it was from SLR PRO @ simlim, for $117 ex gst. my god that kinda money spent (esp for student like me). i wanted to come back the next day with my camera but the guy kept saying its okay, sure no problem (etc etc), anyway got receipt and stuff. oh well. I'm hoping to go back tmr and see if he would do an exchange for something of similiar value. I cant bear to sell to any of our clubsnappers for something like that. well but it does give a nice almost fish-eyeish effect when used on my kit lens when zoomed all the way out.
main intention for it was to take theatre shots (cos i realised my 50mm f1.8 was too cropped for taking an entire stage) but i guess since i cant use it at wide apertures, i cant use it for theatre.
sean: sorry to hear that about your lens. but what is the problem? is it a lens defect or what?
well but i just dont understand the physics behind the glowing