I'm considering changing out the focus screen on my 50D to a grid type screen. My optometrist tells me my eyes are not crooked, but as much as I really try and compose with a level horizon, seems I many times end up having to straighten things up a bit in PP.
How difficult is it to change out the focus screen? Is the tool/instruction provided with the screen sufficient enough to get the job done effectively? Any tips, suggestions, or feedback appreciated.