Quantity is what draws the line between luggage and cargo in an officer's eyes. One camera body with lenses is a tourist; four bodies, lighting rigs, and tripods look like commercial importation or undeclared paid work, and both readings create problems. The classic solution for traveling professionals is the ATA Carnet, an internationally recognized document, obtained in your home country before travel, that lists your equipment and lets it enter temporarily without paying import duties, provided everything leaves with you. Dozens of countries accept carnets, though not all, so check coverage for your destination.
Where carnets do not apply, alternatives include temporary import declarations at the border, sometimes with a refundable deposit, or declaring the gear with receipts and serial number lists.
Separate issue worth flagging: professional filming or photography often needs its own permit or visa category regardless of the equipment paperwork, since working on a tourist entry is an immigration violation. Check both the customs and immigration angles before a working trip.