The Discovery takes several optional add-ons. Here is one that many people seem to like-a Compendium Shade. Basically a bellows for the front of the camera it helps shade the lens.
I found and added a used one to my kit. I find that it is a very flexible piece of equipment and usable with wide and long lenses.
Sadly I do not use it much. When I am out with landscape work I am often using the Singh Ray ND grad filters and those do not work with the Compendium Hood. As such I often just use my hat to shade the lens.