We had a discusssion about this maybe a week or two ago.... I'll find the link to it for you.... I personally have never used either one..... as Danny pointed out people tend to use them as a lens cap more than anything.... and as LP has said they bounce light and have a tendency to produce these strange light glows..... kind of like lens flares in images.....

I am, therefore I create.......
--- michelleamarante.com