Can someone explain why this is necessary when you an just set the self timer on the dslr to 2 seconds, press the shutter and remove your hand from the camera? Also, what is the purpose of using a lens hood? One came with my 55-200mm lens. I noticed there are different shapes (petal shaped, tube shaped) lens hood too, is one type better than the other? And also, when buying filters (ie. UV filters, circular polarizers, etc), does it matter the brand of the filter compared to a "no name" one? Obviously there is a big price difference, but is there also a big difference in quality of the glass too? Thanks !