Gobo OD and ID
OD means Outer Diameter, the outside diameter of the gobo. ID means Inner Diameter, the inside opening. The correct dimensions depend on the fixture and holder design.
What is the difference between OD and ID?
OD means Outer Diameter and describes the outside diameter of the gobo.
ID means Inner Diameter and describes the inside opening.
Thickness is the physical thickness of the gobo and must suit the holder.
Why both values matter
A gobo can share an outside diameter with another gobo and still not fit, if the inside opening or thickness is different. Holder design decides which combination is required.
Do not use ID as the image size
The projected image is created by the fixture optics and the artwork. It is not safe to treat ID as the diameter of the projected graphic.
How to measure
If you have an existing gobo:
- Measure OD across the outside edge
- Measure ID / image area across the inside opening
- Measure thickness
- Check the holder
- Confirm the fixture model
If you cannot measure, photograph the gobo or holder and send the fixture model.
Common mistakes
- Sending only OD
- Confusing ID with artwork size
- Copying dimensions from a different fixture
How to confirm
Use the gobo size guide and gobo compatibility together. Then send the fixture model with your artwork for custom gobos.
FAQ
Is the projected image the same as ID?
Do not assume that the projection image diameter equals ID. ID describes the inside opening of the gobo. The visible image also depends on the fixture optics and the artwork.
Which measurement should I send?
Send OD, ID and thickness if you can measure them, plus the fixture model. If you cannot measure, send a holder or existing gobo photo.
Not sure what size you need?
Send us your fixture model, existing gobo or holder photo. We will help confirm OD, ID and thickness.