This is probably very similar to other questions asked, but I would like a little further clarification. If I upload a photo and my friend comments on it, does this photo then appear in their friends news feed along with their comment and any other comments/likes by me or my other friends? My privacy settings are to my friends only.
No. Only your friends will still see the picture.
Any comments on an item inherit the same privacy as the original item, and never change the privacy of the item.
If your privacy setting for pictures limits the visibility to only your friends, the friends of your friends won't see it, or any comments on it.
However, if they are also your friends, they might get in their news feed either the picture, or a mention of your friend's comment on the picture (depending on what the omnicient holy Facebook Algorithm determines they want to see).