Optimum Realism is too dark at night or in caves with shaders — how do I brighten it

New-to-shaders darkness is normal: realistic shaders deliberately make night and caves dark for atmosphere, and they override Minecraft's own lighting. That's why cranking the vanilla Brightness slider or editing gamma does almost nothing once a shader is on.

The fixes that actually work under shaders:

• Raise the shader's own brightness setting. Open Shader settings (gear next to the shader name) → look for Night Brightness, Minimum Light, Ambient Light, or Cave Brightness. Bump it up a few steps. This is the right knob — it lifts the floor without washing out the look.
• Use client-side Night Vision. Gamma "fullbright" doesn't work with shaders, but Night Vision does. A mod like Gamma Utils lets you toggle it with a keybind — instant visibility in caves without breaking the shader.
• Nudge the in-game Brightness slider to max (Options → Video Settings → Brightness → Bright). It has a small effect under some shaders — worth doing alongside the shader setting.

What not to do: don't try to force gamma past 100% by editing options.txt — under shaders it's ignored, and on multiplayer it can read as a fullbright cheat. Use the shader's setting or Night Vision instead.

If a lighter shader suits you better, Complementary Reimagined and BSL are a touch brighter out of the box than the heavier cinematic packs. Compare shaders.