DSLR Underwater Rig

Let’s talk “serious” UW photographers, in addition to “professionals”. Until about 5 years ago, there were only DSLRs in use,  mainly Nikon and Canon. Then Sony pioneered quality mirrorless, recently joined by Canon, with Nikon a distant third. Olympus cameras are also in use, but are fading away as Olympus has exited camera manufacturing. All of these brands make quality equipment with Nikons and Canons more in use. DSLRs and mirrorless cameras have separate, interchangeable lenses. You need an underwater housing designed to match the specific layout of the camera controls, which varies between manufacturers and usually between models of a manufacturer. In addition, you need a port to mount on the front of the housing, and each lens typically requires a port unique to that lens and make of housing. This is why you often see complete used systems for sale. If you upgrade to a Sony a7r4, for example, you need a new housing to match the button layout and body dimensions  which differ from those of the a7r3.

there are good plastic housings (Ikelite) but aluminum is more favored (Nauticam, Sea and Sea, etc.). The housing can cost as much as th3 camera body, and then there are ports.

A focus light and dual strobes also are important. Inon and Sea and Sea are two of the more popular brands.

there’re lots of threads and alternate opinions here and other boards.

hope this helps.