Camera and Lens Compatibility
Lens compatibility is quite complex, and it took me years to figure out which lens is compatible with which body. I will try to break this down so that you fully understand the compatibility and do not end up buying an incompatible lens for your camera. It is no surprise that each brand has its own specific mount. But, lenses are also specific to the type of camera, i.e. full frame, APS-C and mirrorless bodies have their own specific set of lens. I will cover all the major brands one by one. Please read the full section for your specific brand, else you will miss out on essential information.
Nikon
Nikon DSLR mounts are called ‘F mount’ and mirrorless mounts are called ‘Z mount’.
Nikon lenses (also called Nikkor) made for Nikon APS-C (DX format) bodies have a DX in their name. For example, Nikon AF-S DX NIKKOR 35mm f/1.8G. So Nikon DX lenses are fully compatible with Nikon APS-C bodies.
Nikon lenses made for full frame cameras do not contain DX in their name. For example, Nikon AF-S NIKKOR 70-200mm f/2.8E FL ED VR. These lenses are fully compatible with Nikon full frame (FX format) bodies.
Nikon lenses made for Nikon mirrorless cameras contain a Z in their name. For example, Nikon NIKKOR Z 24-200mm f/4-6.3 VR. Again note that the above concepts still prevail here. The lens I just mentioned is made for Nikon mirrorless FX format (full frame) cameras. Lenses made for Nikon mirrorless DX format cameras contain a DX in their name. For example, Nikon NIKKOR Z DX 16-50mm f/3.5-6.3 VR.
However, Nikon offers a good flexibility here. Nikon offers an adaptor called Nikon FTZ (short for F to Z mount) which you can use to mount Nikon DSLR lenses to mirrorless bodies. But the reverse is not true. You cannot use Nikon mirrorless lenses on a Nikon DSLR body. Why? There is a lot of physics involved and if you are interested, you can read it here (hint: flange distance).
Canon
Canon, however, took a different route. Canon DSLRs have two different mounts viz. EF and EF-S mounts. If you see a red circle on the Canon lens mount your camera will accept EF lenses only. If you see a red circle and a white square, it will accept EF-S lenses as well. That means all EF lenses are compatible with every EOS camera ever produced. EF-S lenses are specially designed for Canon APS-C cameras.
Sony
Pentax, Fujifilm and Olympus
Camera Flash and Compatibility
High speed sync
Flash and Wireless Flash Trigger Compatibility
High speed sync