I have read some of the other questions about lens hoods (for example, this one) and I hope that this is specific enough to not be considered a duplicate.
My understanding is that lens hoods block out "stray light". I had my lens hood on when I was shooting indoors in relatively low light, and someone said to me that I shouldn't do that because it blocks out light.
Based on my understanding, I would think it's fine to keep the lens hood on since it only blocks out light outside the frame. What do you say?