Rotating filter mechanism inside professional cinema and broadcast cameras that holds multiple ND filters in a wheel configuration – allows instant switching between different ND strengths without external filters, providing rapid exposure adjustment during continuous shooting.
What is an ND Wheel?
The ND Wheel is a rotating filter wheel inside cinema and broadcast cameras. It holds multiple ND filters of different strengths, allowing for quick switching without changing external filters.
Basic Principle
| Aspect | Description |
|---|---|
| Type | Rotating filter mechanism |
| Position | Between lens and sensor |
| Capacity | Typically 4-5 positions |
| Activation | Mechanical or motorized |
Typical Configuration
| Position | Filter | Stops |
|---|---|---|
| 1 | Clear (no ND) | 0 |
| 2 | ND 0.6 | 2 |
| 3 | ND 1.2 | 4 |
| 4 | ND 1.8 | 6 |
ARRI ALEXA ND Wheel
| Position | ND Value | Transmission |
|---|---|---|
| Clear | 0 | 100% |
| ND 0.6 | 0.6 | 25% |
| ND 1.2 | 1.2 | 6.25% |
| ND 1.8 | 1.8 | 1.56% |
Sony Venice ND Wheel
| Position | ND Value | Stops |
|---|---|---|
| Clear | 0 | 0 |
| ND1 | 0.6 | 2 |
| ND2 | 1.2 | 4 |
| ND3 | 1.8 | 6 |
| ND4 | 2.4 | 8 |
Mechanics
| Aspect | Description |
|---|---|
| Drive | Motorized or manual |
| Indexing | Precise positions |
| Speed | Fractions of a second |
| Repeatability | Exact |
Operation
| Type | Description |
|---|---|
| Body Button | On the camera body |
| Grip | On the operator's grip |
| Remote | Via wireless |
| Menu | In the camera menu |
Advantages
| Advantage | Description |
|---|---|
| Speed | Instant switching |
| Dust Protection | Enclosed system |
| Consistency | Always identical |
| Workflow | No filter box needed |
Disadvantages
| Disadvantage | Description |
|---|---|
| Fixed Steps | No intermediate values |
| Limited Range | Maximum predetermined |
| Service | Manufacturer only |
| No VND | Variable ND external |
ND Wheel vs. External Filters
| Aspect | ND Wheel | External Filters |
|---|---|---|
| Change Time | < 1 second | 30+ seconds |
| Dust Risk | Minimal | High |
| Vignetting | None | Possible with wide lenses |
| Flexibility | Limited | Unlimited |
| Cost | In-camera | Additional purchase |
Broadcast vs. Cinema
| Type | Description |
|---|---|
| Broadcast | Often 3-4 positions |
| Cinema | 4-5 positions |
| ENG | Fast switching critical |
| Feature Film | More preparation |
Typical Manufacturers
| Manufacturer | Cameras |
|---|---|
| ARRI | ALEXA series |
| Sony | Venice, FX series |
| Canon | C series |
| Blackmagic | URSA |
Maintenance
| Aspect | Description |
|---|---|
| Cleaning | During service |
| Mechanics | Durable |
| Filter Replacement | Workshop |
| Calibration | Precise |
Workflow with ND Wheel
| Step | Description |
|---|---|
| 1 | Assess lighting situation |
| 2 | Select ND pre-emptively |
| 3 | Fine-tune with aperture |
| 4 | When light changes: rotate ND wheel |
When to Supplement Externally?
| Situation | Description |
|---|---|
| Max ND reached | Add external filters |
| Special Effects | Graduated ND, VND |
| Extreme Brightness | Above camera maximum |
| Creative Looks | Black Mist etc. |
Documentation
| What | Why |
|---|---|
| ND Position | Continuity |
| Combinations | With external filters |
| Lighting Conditions | Scene matching |
Best Practices
| Practice | Reason |
|---|---|
| Know standard positions | Quick reaction |
| Think ahead | Light changes |
| External as backup | When needed |
| Document | For post-production |
Today
The ND wheel is a fundamental component of modern cinema and broadcast cameras. The ability to switch between 4-5 ND stops in fractions of a second has revolutionized workflows in changing lighting conditions. Combined with high-quality IRND filters, modern cameras offer a flexibility that was previously only possible with extensive filter sets.