How to Turn On Optifine Old Lighting Shaders in Your World

Optifine Old Lighting Shaders is a shader pack, so it needs a shader loader such as Iris or OptiFine. The pack recreates the classic lighting from OptiFine's old internal shader options without changing Minecraft's look.

Put the pack in the right folder

1. Launch Minecraft with Iris or OptiFine installed.

2. From the main menu, go to Options > Video Settings.

3. Open the shader menu. Iris calls it Shader Packs and OptiFine calls it Shaders.

4. Click the button that opens the shader pack folder. This is the shaderpacks folder inside your Minecraft directory, not the resourcepacks folder.

5. Drop the pack file into that folder. Leave it zipped unless your loader specifically needs it extracted.

Activate it

1. Go back to the shader menu in-game. The pack should now appear in the list.

2. Select Optifine Old Lighting Shaders and click Apply or Done.

3. Load a world and look around in daylight, in caves and at night. Light and shadow should take on the familiar shades of the old OptiFine setups. Blocks, mobs and textures keep their vanilla look.

If the pack doesn't show up, check that it's in shaderpacks and not resourcepacks. Then reopen the shader menu so the list refreshes.