And thanks ... I never knew what "filtering" was called, just that it bothers me when I have to read it.
A lot hinges on what POV you are using. What POV are you using?
He turned to the side and saw- maybe that's what happened, but it's dull and vague. 'Turned and saw' doesn't really give much of an image.
If something catches his attention - that's what you should focus on. If he's sitting on his chair or whatever, cut straight to the event or commotion that caught his attention. If you are in 'his' POV we know he is seeing or hearing the commotion or whatever because if he hasn't heard it or noticed it you can't mention it at all.
POV is 3rd person limited. What if he's in the middle of fighting someone and that's when he notices something else? Is it fine to just mention right away what he noticed? Would readers assume he turned to the side and that's how he saw or noticed something else?
I guess I'm wondering about the best way to transition this. For scenes like what you mentioned, yeah, I just cut straight to what was happening and what he's seeing/noticing. But what about for situations when the character is occupied with something and then something else catches his attention?
What if he's in the middle of fighting someone and that's when he notices something else?
I wonder if it depends on why what he noticed is important? If what he noticed is important because the tide of the battle turned but he doesn't do anything different in the moment, then him noticing isn't the important thing; don't filter. If what he noticed causes him to do something else, like turn and flee, then the fact that he noticed is important and the filtering is more appropriate. Not a hard and fast rule, but might help in some situations.
If he's in the middle of fighting someone, how likely is it that he'll notice something else? Fighting is a pretty concentrated activity.
caw
I think the thing with filtering is if you want the reader to be aware of the character being aware of something, or you just want them to be aware of it themselves. People tend to be a bit more gripped by things they themselves are experiencing, rather than what's happening to other people.