What the standard defines
A nominal diameter of three-eighths of an inch with sixteen threads per inch, cut to the Unified inch series, standardised by ISO as the tripod connection. Any 3/8 stud engages any 3/8 socket. That is the whole of it.
This is the joint that carries a whole camera assembly, and its designation is silent about carrying. The figures that describe carrying — a declared maximum load, a column diameter, a leg section count — are published beside it, by the maker, in the maker’s own terms, and this site reads them there.
What it does not promise
No stiffness. Two stands may present an identical 3/8 stud and flex differently under the same lens. Stiffness comes from tube diameter, wall thickness, section count and the locks between sections; none of those is implied by the thread.
No declared load. A maximum load is a static figure published by the maker for the head or the legs. It describes a mass at rest, not a mass in wind, and not the torque of a long lens tilted forward.
No clamping profile. The thread joins a head to legs. What the head does above the thread — which plate profile it clamps, and whether that profile is published by anybody — is a separate question with a separate answer.
No stud length or shoulder. How far the stud protrudes, and whether it seats against a shoulder, varies between makers and is published inconsistently. A stud that bottoms out before the shoulder meets is a joint that holds by friction on a thread rather than by contact between two faces.
What it works with
Sets of legs, studio and light stands, and the underside of most heads. Above the head, the camera side of the assembly uses the smaller 1/4 thread, printed in eight of this catalogue’s titles. Between the two sizes sits a bushing, which is a change of diameter and nothing more.
What people ask before they commit
Can I put a 1/4 camera on a 3/8 stud?
Not directly, and the part that makes it possible is a bushing — a sleeve threaded 3/8 outside and 1/4 inside. It changes the diameter of the joint and nothing else: the load the stand will hold, the stiffness of the column and the behaviour of the head under torque are unchanged, and none of them is described by either designation.
Why is the larger thread on the legs rather than the camera?
Because that joint carries everything above it, while the screw under a camera carries only the camera. Makers put the larger size where the bending moment is greatest. It is a design convention rather than anything the designation itself requires, and a listing that says which size sits where is publishing something useful.
Last reviewed 12 September 2026