Read the sheet in the order it is installed
Most rotating gobo projector sheets list ten numbers and leave out the three that decide the result. Work from the wall backwards — image size, throw distance, ambient light — and treat everything else as supporting detail. The numbers that matter are the ones you can verify on site with a tape measure and a lux meter.
Lumens, watts and what reaches the wall
Wattage tells you the running cost, not the result. Two rotating gobo projector models at the same wattage can differ by 30% at the wall because of lens efficiency and LED binning. What you actually care about is contrast: the image needs to be meaningfully brighter than the surface it lands on, and that is a lux comparison, not a lumen one.
| Figure | What it measures | How much to trust it |
|---|---|---|
| Lumens | Total light leaving the lamp | Rough sorting tool — ignores lens and gobo losses |
| Lux at the wall | Light arriving on the surface | The number that matters, rarely quoted |
| Watts | Power drawn from the supply | Tells you running cost, not brightness |
The two numbers that must be quoted together
The useful specification is the throw ratio, or failing that a distance-to-image-width table. On a typical rotating gobo projector covering 5–30 m, the zoom lens might take the image from roughly 0.8 m wide at the near end to 3 m at the far end. Once you know the width you need, the throw tells you where the bracket goes — not the other way round.
| Throw | Typical image width | Practical note |
|---|---|---|
| Short, around 5 m | 0.5 – 1.5 m | Bright and easy — most indoor work |
| Mid, around 30 m | 1.5 – 3 m | Where lens quality starts to matter |
| Long, beyond 30 m | 3 m and up | Contrast fails before reach does |
Gobo size, image area and resolution
Gobo size is quoted as an outer diameter, but what matters is the image area — the part the light actually passes through. A 53 mm gobo may only have a 45 mm image circle, and artwork sized to the outer diameter gets cropped. For a rotating gobo projector, ask for both figures before you commission artwork, because a file drawn for the wrong one is wasted.
IP rating and electrical data
Ratings age. A rotating gobo projector that left the factory rated IP65 can lose that rating the first time somebody opens it to change a gobo and reseats the gasket badly. Look for a design where routine access does not mean breaking the environmental seal, or accept that the rating applies to the unit as delivered, not as maintained.
What a good supplier answers without hesitating
The most revealing question is about failure. Ask what the most common warranty claim on this rotating gobo projector is and how it is resolved. A supplier who answers honestly is worth more than one with a slightly better spec sheet.
