Read the sheet in the order it is installed
Nothing on a spec sheet is dishonest; plenty of it is irrelevant. an HD gobo projector sheet will quote lumen output, power draw and beam angle, but what you need is image width at your throw distance and contrast against the light already on the surface. Those require two more numbers the sheet usually does not give you, which is why they are worth asking for.
Lumens, watts and what reaches the wall
Treat the lumen figure as a rough sorting tool and nothing more. It ignores the lens, the gobo transmission and the colour filter, any of which can take a third of the output. For an HD gobo projector in the 50–300 W class, ask instead for measured image lux at a stated distance — a supplier who has that number has actually tested the unit.
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 HD gobo projector covering 6–35 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.
The optical spec most sheets leave out
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 an HD 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
The electrical block is boring and expensive to get wrong. Confirm the input voltage range matches your supply, check whether the HD gobo projector ships with a local plug, and look for CE, RoHS and FCC marks if the install is commercial. A unit that is electrically fine but uncertified will not pass a site inspection in most markets.
Questions worth asking the supplier
Four questions separate a supplier who knows the product from one reading a sheet. What is the image width at my throw distance? What is the gobo image area? Is the IP67 rating for the housing alone or the whole assembly? And what is the lead time on a replacement gobo? A good supplier answers all four in one reply.
