No brightness control for Cinema Display

which cinema display do you have? I have the thirty inch and the brightness buttons are on the right lower right side of the unit plus my brightness keys located at F1 and F2 do darken / lighten the screen. There is no real contrast settings but you can go into display settings / color then click on calibrate then
click the expert check box and go through the steps it will effect brightness and contrast you just need to experiment with the settings to get what you want. You can always go back to the default settings.

I also have a brightness slider when looking at the "display" option for my 30 inch but my two other displays only have "display" with no slider and "color" settings no options menu like I mentioned earlier but when I moved the main menu under "arrangement" to be on the other montitor I was then able to dim that monitor
which is aslo an apple monitor but when I made the third monitor an Acer it had no effect on dimming the display. You should be able to calibrate it darker with the advanced color settings but you must save the profile after you go through the settings.

Try this it worked with my thirty inch, go to Displays in system prefs, then click on options. There is an option half way down for disabling the brightness buttons on the keyboard when I have it checked the brightness buttons on the keyboard don't work and the monitor is locked at full brightness but unchecked it lets you use the keys on the keyboard to dim the display. I have three monitors connected to my mac pro, this only works for the main monitor. I am running 10.6.5 so your options in 10.5.8 may be different.

Does your video card have a second dvi port on it, perhaps try changing ports. Maybe borrow a second monitor from someone and see if anything changes, you could also upgrade to snow leopard and you might get the brightness slider. Also you could zap your pram to set your computer back to it's default settings, seems like you may have a system glitch of sorts because the color settings should change the monitors preset. Tomget default settings zap the pram by holding down the apple shift p and r buttons, all four at the same time then hit the power button or have someone do it for you, keep holding them until you hear the computer chime twice if not three times then let go and the computer will boot as usual.
This restores some parameters to the factory settings, other than that I am out of ideas....

I have the same issue.. and I do have two Cinema displays, exactly the same ones. A1081 from 2005
One has the brightness control slider and the other doesn't. (I can change the brighness on the side of the monitor, but have no idea at what setting I am) I calibrated both using the expert mode, and wow, they looked so different, like black and white! Then I calibrated with Spider Pro3 and still they are different, but not as much. Contrast being the main difference.
Not sure what to do...as I do require the monitors to be accurate!

I had exactly the same problem in hooking up my new 27" Apple Cinema Display to my new iMac 27"...no brightness slider and no check box to disable automatic ambient control. Plus which, the screen was too dim to see much. Using the keyboard to make it lighter (or darker) produced no results at all. After a lengthy consultation with two Apple tech support people, they diagnosed it as a hardware problem and suggested that I return it for a new one.
My son brought his MacBook Air over, hooked it up to the monitor, and both the brightness control slider and the ambient light control box appeared. He corrected the brightness and unchecked the ambient control, re-attacheded it to my computer and all is well. Plus which, the brightness slider and the ambient control box now appear on my iMac system preferences.

I was having the same issue on my MacBook Pro. Here is what I did to resolve it:

1. Ensure lid of laptop is open
2. Plug in power, mini-display, AND USB from the Cinema Display into MBP
3. Restart computer ( *this was the key step for me)
4. When computer comes back up, launch System Preferences > Displays and you should now see the brightness option that was once hidden!

Yes, I have two recently-purchased 27" Cinema Displays connected to a brand new Mac Pro. One has a brightness slider in the LED Cinema Display control panel (System Prefs->Displays). No amount of fiddling around and rebooting seems to be able to fix the problem. The brightness between the displays is noticeably different, but not so annoying as to make it unusable. But I'd sure rather find a workaround than have to ship this screen back for a replacement. Grrr.

I have a new 27" iMac and a 27" Apple display connected to it, took a while to get the colors calibrated between the two (shipped WAY off from each other). Periodically the slider for the 2nd display brightness disappears and I end up rebooting to get it back. The ambient light sensors for the two displays are freakishly off from each other, so numerous times each day I am adjusting one or both displays to a comfortable level. I've reset PRAM and SMC without successfully fixing the issue.

Also of note: The iMac display dims prior to turning off the display while the other display stays at full brightness; could be part of the problem methinks.

Thanks, gilletty, that solved it for me!