U8lib setContrast only has two options?

So I installed this library GitHub - olikraus/U8glib_Arduino: U8glib library for Arduino

and I'm trying to control the brightness of the OLED, I believe the values are from 0-255, I put in 10 and got a noticeable dimming of the screen, but id say it looked like 50% less brightness. I tried making it 0 or a negative number to see if I could turn it almost off, but nope not working, so I checked to see if any other values between 0-255 have a noticeable affect on brightness, nothing. Anyone else have the same experience?