It's possible to adjust the display contrast and brightness in the SPD-30.
Here's how:
1. Press MENU.
2. Turn the function 1 knob to highlight "SYSTEM."
3. Press the function 3 button (ENTER).
4. Turn the function 3 knob to adjust the contrast.
5. Turn the function 1 knob one 'click' clockwise to highlight "LCD Brightness."
6. Turn function 3 to adjust the brightness.
7. Press the BACK button when you're finished. The new settings are saved automatically.