Camera Rig Thread and Mount Standards Chart
Short answer
A camera rig uses six mounting standards. The 1/4-20 and 3/8-16 threads are friction joints with no anti-rotation. ARRI locating points add two 4.5mm pins at 21mm spacing. NATO is a 44mm dovetail rail. ARRI rosettes are 31.75mm with 60 teeth. Rods are 15mm at 60mm centres or 19mm at 104mm centres.
Mounting standards are the vocabulary of rigging, and knowing them prevents both buying a part that will not fit and buying one that fits and then works loose. The critical distinction is between friction joints and anti-rotation joints. A plain thread relies on how tight you did it up; a SmallRig Lightweight NATO Top Handle on a rail and an ARRI pin pair do not. The table below has every dimension.
The complete standards table
| Standard | Dimensions | Anti-rotation | Used for |
|---|---|---|---|
| 1/4-20 UNC thread | 0.25 in diameter, 20 threads per inch | None | Cameras, small accessories, cold shoes |
| 3/8-16 UNC thread | 0.375 in diameter, 16 threads per inch | None | Tripod heads, baseplates, heavy mounts |
| ARRI locating point | 3/8-16 plus two 4.5 mm holes at 21 mm apart | Two pins | Anything carrying offset weight |
| ARRI 1/4-20 locating point | 1/4-20 plus two 4.5 mm holes at 21 mm apart | Two pins | Lighter anti-rotation mounts |
| NATO rail | 44 mm dovetail, defined profile | Clamp geometry | Handles, monitor mounts, accessories |
| ARRI rosette | 31.75 mm diameter, 60 teeth | Toothed interface | Handgrips and adjustable arms |
| Cold shoe | ISO 518 profile, no electrical contacts | Partial | Microphones and light accessories |
| 15 mm LWS rods | 15 mm diameter, 60 mm centres | Two rods | Matte box, follow focus, lens support |
| 15 mm studio rods | 15 mm diameter, 104 mm centres | Two rods | Uncommon, older equipment |
| 19 mm studio rods | 19 mm diameter, 104 mm centres | Two rods | Heavy cine builds |
| Arca-Swiss plate | Dovetail, roughly 38 mm wide | Needs a stop | Tripod heads and gimbal plates |
| Manfrotto 501 plate | Proprietary, with a pin | Pin | Manfrotto fluid heads |
| Sony Multi Interface Shoe | Cold shoe with digital audio contacts | Partial | Sony XLR handles and microphones |
Read the anti-rotation column first. Every load on a rig that sits away from its mounting point is a lever, and a lever on a friction joint works itself loose no matter how firmly it was tightened. Anything carrying a monitor, a handgrip or a battery plate should use a standard from the anti-rotation rows.
Why the pins matter
An ARRI locating point is a threaded hole flanked by two 4.5mm holes spaced 21mm apart, and the mating accessory has two pins that drop into them. The screw provides clamping force and the pins prevent rotation. That combination is the difference between an accessory that stays put and one that slowly rotates through a shoot day.
The physics is straightforward. A monitor on an arm applies a torque at its mount, and a single screw resists that torque only through friction between two flat surfaces. Vibration and repeated small loads gradually overcome that friction. Two pins in two holes resist the torque mechanically and cannot slip.
This is also why a NATO rail is such a good standard. The clamp geometry engages a dovetail along its whole length, so rotation is impossible and the accessory can be positioned anywhere on the rail rather than only where somebody drilled a hole.
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.
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
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
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 priceRod standards in detail
| Standard | Diameter | Spacing | Rod height above base | Suits |
|---|---|---|---|---|
| 15 mm lightweight | 15 mm | 60 mm centres | 85 mm typical | Mirrorless and small cinema rigs |
| 15 mm studio | 15 mm | 104 mm centres | Varies | Uncommon, mostly older gear |
| 19 mm studio | 19 mm | 104 mm centres | Varies by camera | Large cine bodies and cine zooms |
The rod height standard is why a matte box, a follow focus and a lens support all line up on any camera without shimming. If your baseplate has adjustable rod height, set it to the standard rather than to whatever looks convenient, because every accessory you buy later assumes it.
Screw lengths and thread depth
A screw longer than the threaded depth of the hole bottoms out against the base of the hole and stops turning before it has clamped anything. The accessory then feels tight and is not, and it comes loose during the day. This is a very common and very avoidable failure.
The fix is to keep a small selection of 1/4-20 and 3/8-16 screws in several lengths, and to check that a screw turns freely for its full engagement before it goes tight. If it goes tight suddenly and the accessory still moves, it has bottomed out.
Overtightening is the other end of the same problem. Most rig components are aluminium, and a 1/4-20 steel screw driven hard into an aluminium thread strips it. Firm by hand is correct; a tool is for holding while a lever is tightened, not for adding force.
Adapters worth owning
- A 3/8-16 to 1/4-20 reducing bushing, which lets a 1/4-20 accessory mount to a 3/8-16 hole. The most useful single adapter in a kit.
- A NATO clamp with a 1/4-20 thread on top, so any threaded accessory can live on a rail.
- A cheese plate with both thread sizes, for adding mounting points wherever a rig lacks them.
- A rosette adapter with a NATO clamp, for adding an adjustable handgrip to a cage that has no rosette.
- A short magic arm with an ARRI point at one end, for the position that has no thread anywhere near it.
- Spare 4.5 mm ARRI pins, because they are tiny and they get lost.
What is not worth owning is a large collection of speculative adapters. A SmallRig Multi-Functional Cheese Plate and a SmallRig 9.8-inch Magic Arm solve most unexpected mounting problems between them, and buying adapters in advance of a specific problem is how a drawer fills with aluminium.
Assembly rules that prevent failures
Use the anti-rotation standard wherever one is offered, even when a plain thread would work today. The cost is nothing and the failure it prevents is a dropped monitor.
Use the shortest arm that reaches. Every millimetre of arm length multiplies the torque at the mount, so a 4 inch arm carrying a monitor is a much smaller load on its mounting point than a 10 inch one carrying the same monitor.
Check accessory mounts at the start of every shoot day rather than after something moves. A set of hex keys in the bag and thirty seconds of checking prevents the specific failure where something works loose during a take and nobody notices until the edit.
Next, from here
- Mounting standards explained
The same material with the reasoning.
- 15mm versus 19mm rods
Which rod standard to build on.
- Best camera cages
What provides most of these points.
- Rig balance and centre of gravity
Why offset loads work mounts loose.
- Rigging a follow focus
Rod height in practice.
- Rig weight calculator
What all this hardware adds up to.
Common questions
- What is the difference between 1/4-20 and 3/8-16?
- They are two screw sizes: 1/4 inch diameter at 20 threads per inch, and 3/8 inch at 16 threads per inch. The smaller is on cameras, cold shoe adapters and light accessories; the larger is on tripod heads, baseplates and anything carrying load. Both are friction joints, so neither prevents an accessory rotating around its screw under a lever load.
- What are the dimensions of an ARRI locating point?
- A 3/8-16 threaded hole flanked by two 4.5mm diameter holes spaced 21mm apart, centred on the thread. The mating accessory has two pins that drop into those holes so the screw clamps and the pins prevent rotation. A 1/4-20 version of the same pattern exists for lighter accessories, using the same 4.5mm holes at 21mm spacing.
- How wide is a NATO rail?
- Forty four millimetres, with a defined dovetail profile that a matching clamp engages along its whole length. That geometry makes rotation impossible and lets an accessory be positioned anywhere along the rail rather than only where a hole was drilled. It is the best mounting standard on a camera rig and worth choosing accessories around.
- What is an ARRI rosette?
- A 31.75mm diameter toothed circular interface with 60 teeth, used for handgrips and adjustable arms. The teeth let a grip be set to any angle and then locked, with rotation prevented mechanically rather than by friction. Wrist angle is what makes a shoulder rig comfortable for an hour rather than painful in ten minutes, which is why rosettes exist.
- What rod height should a 15mm baseplate be set to?
- Eighty five millimetres from the camera baseplate to the rod centreline is the common standard on 15mm lightweight systems. That standard is why a matte box, follow focus and lens support line up on any camera without shimming. If your baseplate is adjustable, set it to the standard rather than to whatever is convenient.
- Why does my accessory keep working loose?
- Almost always because it is on a plain thread and acting as a lever. A single screw resists rotation only through friction between two flat surfaces, and vibration gradually overcomes that. Move it to an ARRI locating point or a NATO clamp. The other cause is a screw longer than the thread depth, which bottoms out and feels tight without clamping.
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