Customs Issues When Traveling Abroad
Prior to your departure, prepare a "Certificate of Registration" form (CBP Form 4457) for your personal articles, including cameras and laptops. The certificate is your proof of ownership and will exempt your property from customs duties. The form may be printed here: www.cbp.gov/linkhandler/cgov/toolbox/forms/4457.ctt/cbp_4457.pdf.
Before you leave the country, take your equipment and the completed form to your local U.S. Customs and Border Protection ("CBP") office. You may locate an office convenient to you at www.cbp.gov/xp/cgov/toolbox/contacts/ports/. Some airports have onsite offices, but they may be past security so that you cannot verify any equipment that you check. A CBP officer will compare your items with those listed on the form, will sign the form, and will return it to you. Keep it with you when re-entering the United States to avoid large customs duties on equipment that you already owned. Note that any repairs performed on the equipment while out of the country are subject to customs duties. Keep the form for future trips, as well, because it is valid for the registered articles as long as the form is legible.
Before you take that next photography trip abroad, do some important preventive work for that dreaded customs inspection on the trip home.
Take my advice; get professional help.