Sentence:  I had frequently had to explain to cameramen that only in the early morning or late in the evening did <WSD>sunbeams</WSD> fall from the window as flat as they were usually found in films. The sun being higher during the hours of work, another way of showing <WSD>sunbeams</WSD> had to be found. 
Meaning of the word marked with <WSD> tags:  A visible, narrow, and intense (relative to ambient light) ray of sunlight.