After 10.6.8 Mini Displayport to HDMI PROBLEM

I have the same issue, I connected my iMac with Dell workstation, and after upgraded to 10.6.8, I can't adjust my brightness any more.

Same problem here. Late 2009 iMac 27" running as target display for MacBook Pro 15" with Thunderbolt.

My eyes are bleeding.

Add me to the list too. I'm really upset. After the 10.6.8 update I can't adjust the brightness on my 27" iMac when my cable box is plugged into the Mini DisplayPort. For TV viewing there's no way to adjust the brightness anymore. Works fine on the desktop but when using the iMac as a display it doesn't work. Furthermore a friend of mine that's a developer has the Lion GM and his 27" iMac has the same issue. Apple needs to fix this but I'm afraid when we all get Lion next week we're going to have the same issue. I had to restore my iMac back to 10.6.7. I won't be able to upgrade to Lion if they won't fix this. I'm really ****** rigtht now.

Yeah this is pretty terrible. I used to have a calibrated imac as a secondary monitor for my macbook pro, now I have an eye scorcher that doesn't have any functional relationship with my printer at all, nor with the printer my boss sends images off to. A fix to this would be much appreciated.

I received a message from Apple support yesterday evening stating that Apple Engineering has received reports of this symptom and are investigating. Further updates, if any, may come by way of a software update.

Helps to know they are working on it. Not too thrilled about the "if any" part :-\

Ah ok, I found a fix. Using the app "shades" you can individually control the brightness of each monitor connected, you even get a nice little menu bar icon to quicly change the brightness. It is a preff pane you install and it was pretty easy to set up, fixes my evil eye burner 🙂

http://www.charcoaldesign.co.uk/shades

Actually I've tried Shades but the only issue with it is it's like putting on sunglasses (haha, henceforth the name shades) and all it really does is add a darker tint to the screen rather than just lowering the brightness. IMO, Shades is harder on the eyes. But thanks much for the help. this has been quite frustrating for many I see.

I'm experiencing the same issues with my Late 2010 iMac 27" whilst in Target Display Mode.

This doesn't appear to be a problem that can be solved via Mac OS X software, as the backlight itself switches to full brightness when the input source is changed.

Apple knows.

While I'm certainly not disputing what you're saying, I do find it odd that this same issue has ended up in the Lion GM. I certainly can't upgrade to Lion until I know for certain that they've fixed this. I use my 27" iMac as my living room TV and for nighttime viewing it's completely unusable unless I put on sunshades to watch TV.

Those with developer accounts can report the problem via the Bug Reporter, those without can do so through the iMac Feedback page. I've created a ticket but have not yet recieved any indication of when this will be fixed. I hope that the more people who complain about this to Apple, the faster they will fix it.

My eyes are melting here.

I'm not going to defend Apple, but they somehow let this slip by until people started reporting it after the 10.6.8 update last week. This would explain how it got into Lion as well. They do in fact know about the issue, although they have not given any clear indication of when/how it will be corrected.

That explanation sounds about right. I would rather Apple releases another Brightness Update rather than waiting until 10.6.9 or 10.7.1 to fix it.

Same problem. OSX 10.6.7 was fine. iMac 27" late 2009 used as monitor for macbook pro mid 2010 both running 10.6.8 does not work.

To stress the urgency: please report the problem to Apple (the more reports the better). From a post above:

Those with developer accounts can report the problem via the Bug Reporter, those without can do so through the iMac Feedback page.

Now let's hope for a fix!