Is it normal that i masturbate looking at my straight friend pictures.

I have a friend, we like to hang out together, am gay he is straight and I know it... Well I like to take some pictures of him, because thats the only way I get horny when I masturbate.. Its the only way I can ejaculate. I do that all the time I always think that he is there jerking off with me, that am giving him head...Someone help me..