If your DH is a really serious photographer and you want to get him the best laptop for photography, then you should at least look at a 15" MacBook Pro.
The retina screen is amazing and, coupled with a suitable photogpraphic app, the quality and clarity of images and the ability to manipulate them cannot be matched by mid range computers.
Yes, I know how expensive they are. I suppose you should think about the quality of the eqipment that DH uses to take his photos. If he takes pride in his photography, he needs a computer that can do them justice. This is really just a suggestion as no one has mentioned Apple so far. You need to spend some time looking at laptops and ask questions about their photographic display quality and the best photographic apps that can be run on them. Another thing to bear in mind is a back-up solution for precious photos.