Coming out to grandparents? Tips?

Okay so I'm 20 now and I've been out with everyone including my parents since I was 16. I'm extremely close with both sets of grandparents but have never felt the right time to 'come out' to them. I know they love me a lot but they are obviously from a much different generation and I would hate to upset them/cause problems in our relationshipHowever I now have a boyfriend and have done for the last year. It's getting to the point that I'm going away with him and showing them photos of me and my "friend "and they think he's just that. There isn't really a need to come out as they know me so well.Any tips or advice? Thanks