Camera Rig Mounting Standards: Threads, Pins, Rails and Rosettes

A camera rig is a set of interlocking standards, and knowing which is which is what stops you buying a part that will not fit or, worse, one that fits and then works loose. The important distinction is between friction joints and anti-rotation joints: a plain 1/4-20 thread relies on friction alone, while a SmallRig Lightweight NATO Top Handle clamps to a rail and an ARRI locating point uses pins. Anything carrying weight should use the second kind.

The two thread sizes, and where each is used

The 1/4 inch by 20 threads per inch screw, written 1/4-20, is the universal small camera thread. It is on the base of almost every camera, on every cold shoe adapter and on most small accessories. It is convenient, it is everywhere, and it is a friction joint: nothing prevents the accessory rotating around the screw except how tight you did it up.

The 3/8 inch by 16 threads per inch screw, written 3/8-16, is the larger standard. It is on tripod heads, on baseplates, on the underside of heavier cages and on anything expected to carry real load. It is stronger, and on its own it is still a friction joint.

Most rigs use both, and most cages provide both. A SmallRig Multi-Functional Cheese Plate at around $23 is a flat plate covered in a grid of both thread sizes, and it exists precisely because a rig always ends up needing a thread somewhere the manufacturer did not put one.

ARRI locating points, which are the actual fix

An ARRI locating point is a 3/8-16 threaded hole flanked by two 4.5mm holes spaced 21mm apart. The mating accessory has two pins that drop into those holes, so the screw provides clamping force and the pins provide anti-rotation. That combination is what stops an accessory rotating around its screw under a lever load.

This matters wherever a load is offset from its mount, which is nearly everywhere on a rig. A monitor on an arm, a handgrip, a battery plate and a top handle are all levers, and a lever on a friction joint slowly works itself loose no matter how firmly it was tightened.

The practical rule: if a cage offers ARRI points where you plan to carry weight, use them, and buy accessories that have the pins. If it only offers plain threads there, expect to check the tightness through the day.

NATO rails, the standard worth standardising on

A NATO rail is a dovetail strip 44mm wide with a defined profile, and a NATO clamp slides onto it and locks with a lever. No tools, no rotation, and the accessory can be positioned anywhere along the rail rather than only where somebody drilled a hole.

This is the best mounting standard on a camera rig, and it is worth choosing gear around. A SmallRig Lightweight NATO Top Handle bought today fits any NATO cage you own in five years, and a SmallRig Monitor Mount with NATO Clamp positions a monitor exactly where your eye wants it rather than where the thread happens to be.

The one thing to watch is that some cheap rails are cut slightly out of specification, which produces a clamp that either does not close or does not grip. Sticking to known brands avoids this, and it is a genuine reason not to buy the cheapest available rail.

The three parts that use these standards

$23 to $32. A NATO handle, a NATO monitor clamp and a cheese plate for adding threads where none exist.

Essential $25.42

SMALLRIG

SmallRig Lightweight NATO Top Handle

A NATO handle comes off in one motion without tools, which is the difference between a rig that packs down and one that fights you.

Mount

NATO rail

Needs a NATO rail on the cage.

Check price

Monitor mount $31.99

SMALLRIG

SmallRig Monitor Mount with NATO Clamp

Clamps a 5 or 7 inch monitor to a NATO rail and swivels, which keeps the HDMI strain off the camera port.

Fits

5 to 7 in monitors

Better than a cold shoe for anything heavy.

Check price

Mounting $22.99

SMALLRIG

SmallRig Multi-Functional Cheese Plate

A plate of 1/4-20 and 3/8-16 holes with locating pins, which is how a rig gains a mounting point without drilling anything.

Threads

1/4-20 and 3/8-16

Cheap, and it solves a lot.

Check price

Every standard in one table

Two rows there deserve attention. The rosette is the standard nobody explains: a 31.75mm toothed disc that lets a handgrip be set to any angle and then locked, which is how a shoulder rig gets a comfortable wrist position. And the two rod standards use different spacings as well as different diameters, so a 19mm accessory does not fit 15mm rods even with sleeves.

Rods: 15mm lightweight and 19mm studio

Fifteen millimetre lightweight support, usually written 15mm LWS, uses two rods at 60mm centres below the lens. Nearly everything in the enthusiast and small-production market uses this, including the SmallRig Baseplate Kit with 15mm Rod Clamp and the SmallRig 15mm Carbon Fibre Rods, 12 inch pair carbon pair, and it is the right standard for any rig built around a mirrorless or small cinema body.

Nineteen millimetre studio rods sit at 104mm centres and are what large cine cameras use. The rods are stiffer, the spacing is wider, and the whole system carries far more weight. It is the wrong choice for anything under about 20 lb, because the rods and accessories weigh more and buy you rigidity you do not need.

A Tilta 15mm Lens Support on rods is worth mentioning here, because it solves a specific problem: a heavy lens hanging off a camera mount puts a bending load into the mount itself. Supporting the lens barrel from below transfers that load into the rods instead, and it is required on anything long or heavy.

Cold shoes, and why not to trust them

A cold shoe is the flash mount on top of a camera, without the electrical contacts. It holds a microphone perfectly well, and it will hold a small light. It is a sprung metal channel designed for the mass of a flash unit, held by friction against a small thumbscrew.

What it should not hold is a monitor. A monitor on an arm on a cold shoe is a lever on a friction joint at the top of the rig, which is the worst combination available. It will rotate slowly through the day and it can fail suddenly if the rig is knocked.

Use cold shoes for microphones, small lights, timecode boxes and receivers. Use a NATO clamp or an ARRI point for anything heavier. That single distinction prevents most of the accessory failures that happen on small rigs.

Practical assembly rules

1. Check screw length before tightening. A screw longer than the threaded depth bottoms out and damages the receiving part rather than clamping anything.
2. Use the shortest arm that reaches. Every millimetre of arm length multiplies the torque on the mount at the other end.
3. Tighten by hand where a hand tool is provided, and stop when it is firm. Overtightening a 1/4-20 into aluminium strips the thread.
4. Mount heavy items low and close to the centre of mass, because height and offset both cost you more than mass alone does.
5. Use the anti-rotation standard wherever one is offered, even when a plain thread would work today.
6. Carry a set of hex keys and check the accessory mounts at the start of every shoot day, not after something moves.

A SmallRig 9.8-inch Magic Arm at around $20 is the exception to the shortest-arm rule, because sometimes reach is exactly what you need. Just be aware that a 9.8 inch arm carrying a monitor multiplies that mass considerably at the mount, which is why it belongs on an ARRI point rather than a cold shoe.