I have a situation that confuses me regarding calibrating an IMac 24" and a MacBook Pro 17" with the Eye One D2.

When I go through the steps for calibration I use "Advanced" mode with the I1D2.
When I get to the luminance indicator the target luminance is 110 cd/m2 but the actual measured luminance is 145. (with the IMac and somewhat similar with the MBP)

145 is with the Brightness slider in the Display Preferences moved all the way to the left (minimum).

How can I get the luminance down to the target if I can't change the slider anymore? Am I missing something?

Any help is appreciated.

Thanks

d

I have a 24" iMac, too (matte display).

140 cd/m2 is the minimum luminance you can achieve with this model.

I set mine to these 140 cd/m2. Got to work out until I can splurge for an Eizo ColorEdge.

There is a freeware, Shades, that can reduce brightness more, but it has a bug that ruins color calibration (see x-rite site). There is an older version that is said not to have this bug, but I'm not particularly trusting in this.

I know, most recommendations are for 120 cd/m2.

But it's not that much of a standard.

Martin Evening writes in his "Photoshop CS3 for Photographers":

" A target of around 140 candelas m2 is ideal for a desktop lcd display" (page 107, side bar).

So, set your display to the lowest brightness and then calibrate. You should be fine.

Just don't forget to use the native white point.

Boy, am I glad I didn't upgrade to the 24" iMac. I'm still stuck with my 2004 G5 iMac running at 90 cd/m2 and it's Brightness slider is about 3/8 inch from the left.

I've calibrated to 120 cd/m2 and found it produced blinding whites in my cave like lighting environment. I'ld have to get two 40 watt 4 foot Sunshine flourescents to match the brightness.

Why do they have to keep changing the specs on these units when they were just fine as they were?

They change it for the same reasons they sandwich more and more megapixels into Point-and-shoots: because the marketing guys of those companies can't find a different way to market but higher numbers.

Screen brightness has been a horsepower value for screens for a while, like those idiotic response times (some low level displays are much "faster"than higher end ones).

Regarding the 140 cd/m2, it's not bad. It probably depends on the screen, too. And, as quoted, Martin Evening, which is quite an authority in these technical issues, describes this value as ideal.

So, no problems here.

But, of course, a nice Eizo Coloredge with its wide gamut would be a nice thing to have.

Thanks for the added info.

While searching the net I also found out something from the Xrite support pages that I've cut and pasted here that may help others also. (hope I haven't violated some copyright thingy :-) )

" " " " " "
Q: I try to calibrate the Luminance for an iMac display by using the Brightness slider in the MacOS X system preferences panel 'Displays', but it seems that the Eye-One Match does not recognize my changes. The Luminance value reported by Eye-One Match is not turning down, even if the Brightness has now been set to '0'. What am I doing wrong?

A: The Eye-One Match software cannot measure the changed Brightness / Luminance, as long as the window of the control panel 'Displays' is still open. So please adjust the Brightness slider as desired, close the 'Displays' control panel, then wait a second until the eye-One match software has actualized the measurement values. if needed, open the 'Displays' control panel again, adjust Brightness again, close control panel and wait for actualized measurement values. Please repeat this procedure until you have reached the desired Luminance.
" " " " " " " "

regards
d

You can adjust the brightness from your keyboard, using the f14/f15 keys.

Anyway, you don't need to adjust it, because you are going for the lowest brightness setting.

Reduce the brightness to the minimum, and then start the calibration process.

As far as I know, if you needed more brightness for a different task than photo editing, you can turn the screen up again, and then back down for editing.

But, to be honest, I got used to the lower brightness, and wouldn't want to crank up the display.

Boy this is like a bad penny. Just keeps coming back again and again and again.

The Imac by itself will only go as dark as the slider permits. However, you can use calibration software to adjust brightness in the video card. You can also make color adjustments in the video card if you find native not to your liking. And yes, you may run the risk of creating some banding because of lost tonal range. But you have a choice, critical color and brightness matching with a small amount of banding, or perhaps not being able to have a brightness or color match with no banding. It's an Imac not an eizo. There are compromises inherent in the choice.

I believe ColorEyes does a pretty fair job of calibrating displays that cannot be dimmed far enough to reach the desired luminance.

Nicely said.


Edmund