Lots of good advice, but I seem to see a little bit of an issue concerning a lack of basic respect on the part of your hubby.
It could be jealousy that you have a hobby that you enjoy, it could be jealousy that it takes you away from him. It could be something entirely different and your hobby just triggers on this by coincidence.
In any case, he is the one that needs to learn to respect your desires and wishes. Something as basic as a hobby should not be the source of stress in a family unless that hobby takes priority over more important things such as working on the relationship. Obviously, a nice long serious conversation is due.
I'd also like to suggest that there are times that you take walks and purposefully leave the camera at home and other times that you take your camera with you. In either case, talk it out and let him know that as long as he respects your desires to continue in this hobby, you are willing to go 50-50 with him on this.
Initially this may cut into your camera time, but its a small price to pay for peace between both of you... and in time, if he is mature enough to see it as a form of pleasure for you, he will relax his reservations on this and let you get more serious about it.
Once he sees that you can bring in a little fun money with your hobby, be mindful. If he is the kind easily threatened, it could raise another stink... but let's hope that it has the opposite effect. The argument that the money this job brought in could be used for a private weekend get-away for the both of you just may entice him enough to send you out to get more jobs... lol.
Good luck in your endeavors.