basically now I don't only teach about photography,
I now teach on how to set up a blog using Wordpress
The main purpose of a hood is to prevent stray light from entering the lens through the side of the lens. Light from just outside the photo border can still enter the lens, bouncing inside the barrel and reflecting off the lens surfaces to reach the image sensor indirectly.
This light can reduce the contrast and color saturation of the photo. This is why movie cameras are always used with a hood (matte box), as can be seen in any "The Making of ..." movie documentary. With the vast sums of money spent on making a movie, only the best image quality will do. Furthermore the price of hood is cheaper whereas the special mounted ones will cost u more.I bought a lens hood for about RM20 for my 18-135 mm and it take me 2hours of searching up and down at Lowyat and Sungei Wang.