77GH59B B-size metal gobo holder for ETC Source 4
A Rosco B-size metal gobo holder made for ETC Source 4 profiles. It holds a B-size metal (steel) gobo and slides into the fixture’s gobo gate so the pattern sits at the focal plane and projects sharply.
Image: Rosco
Holds the pattern exactly where the lens needs it
A profile spot projects whatever sits in its gate. The holder keeps the gobo flat, centred and at the focal plane, so the image focuses cleanly — and lets you change patterns without handling the gobo inside a hot fixture.
- Holds one B-size metal (steel) gobo flat and centred in the gate
- Made to fit ETC Source 4
- Positions the pattern at the focal plane for a sharp image
- Lets you swap gobos quickly between scenes or shows
Pattern projection on stage, set and site
Theatre & dance
Breakups, windows, foliage and texture from ETC Source 4 rigs — load a gobo, focus, done.
Events & corporate
Logo, monogram and pattern projection on walls, floors and stage sets.
Film, TV & photography
Hard-edged shadow patterns such as blinds, windows and leaves on set or in the studio.
What it is — and what it isn’t
Use it for
- Loading a B-size metal (steel) gobo into ETC Source 4
- Keeping spare holders pre-loaded for quick pattern changes
- Theatre, events, film and architectural projection
- Standard and custom Rosco steel gobos in this size
Don’t use it for
- Glass gobos — use a dedicated glass holder for your fixture
- Gobos that aren’t B-size — other sizes won’t seat correctly
- Fixtures not listed — gate designs differ between makers and models
- Moving-light gobo wheels — those use their own fixture-specific gobos
Loading the holder
- Switch off the fixture and let it cool — the gate area runs hot.
- Place the B-size steel gobo in the holder so it sits flat and centred, then close or clip the holder.
- Slide the holder fully into the gobo slot/gate on the fixture.
- Switch on and focus the fixture until the pattern edge is sharp.
- Text or logos read wrong? The lens inverts the image — flip or rotate the gobo in the holder and re-check.
Key details
| Brand | Rosco |
|---|---|
| Part number | 77GH59B |
| Holder size | B-size — for 86 mm outside-diameter gobos |
| Rosco B gobo size | 86 mm outside diameter, approx. 64.5 mm maximum image area |
| Holder type | Metal — for metal (steel) gobos |
| Fits | ETC Source 4 profiles |
| Supplied | Holder only — gobo sold separately |
Common questions
Which Rosco holder do I need for an ETC Source 4?
It depends on the gobo size and type. Rosco’s chart lists 77GH59B (B-size metal), 77GH61A (A-size metal) and 77GH62A (A-size glass) for the Source 4, plus the B-size steel sandwich holder. The Source 4 Junior takes M-size: 77GH63M (metal) or 77GH64M (glass).
What does a gobo holder do?
It holds the gobo (a patterned steel or glass disc) and slides into the gobo gate of a profile/ellipsoidal spot so the pattern sits at the focal point of the lens. Focusing the fixture then gives a sharp projected image.
What’s the difference between a metal and a glass gobo holder?
Metal holders are made for thin steel gobos. Glass gobos are thicker and fragile, so they need a glass holder built to retain them safely. Pick the holder to match both your fixture and your gobo type.
What size gobo does this holder take?
B-size. Rosco lists B-size gobos at 86 mm outside diameter with an approximate 64.5 mm maximum image area. Your design must sit inside the image area to project fully.
Is a gobo included?
No — this is the holder only. Choose a Rosco standard gobo in the matching size and type, or order a custom gobo through CFATS.
Holder-to-fixture compatibility is taken from Rosco’s gobo holder chart. Gate designs can change between fixture generations, so check your fixture model and gobo size before ordering, and test-fit before the show. Sizes and compatibility on this page are a guide only.
Not sure which holder fits?
Send us your fixture make and model and we’ll confirm the right Rosco holder and gobo size before you order.
