Brightness and Contrast Ratio
The monitor’s Brightness and Contrast are set at 80% and 70%, respectively, by default. I got a 100nit white by selecting 34% Brightness and 50% Contrast.
The contrast ratio isn’t high. It’s about 500:1 by default but much worse at any other settings. The fact is the ZM-M240W is one of the very few monitors that use the matrix rather than the backlight lamps to regulate their brightness. As a result, lowering Brightness below the default level does not reduce the level of black whereas increasing it above the default level transforms black into gray. I'd advise you not to touch the Brightness setting at all in monitors with matrix-based brightness regulation.
The average nonuniformity of brightness on black is 5.5% with a maximum deflection of 23.7%. On white, the average and maximum are 6.7% and 19.6%, respectively. As you can see in the picture above, the monitor has a bright spot in the middle of the screen. There is also a bright area along the bottom of the screen when it outputs a black fill.
The gamma curves are not ideal, but acceptable at the default settings. There are no critical defects in lights or darks.
Being regulated through the matrix, the Brightness setting, when reduced, makes the curves sag in the area of dark halftones. It means that darks are displayed as black. That’s the fundamental shortcoming of the matrix-based regulation as opposed to monitors with backlight-based brightness regulation on which dark halftones get darker but still remain distinguishable when you lower Brightness.
I don't even get the purpose of the matrix-based regulation in this monitor. There are no reasons for that. Even the flickering of the screen at a high frequency wouldn’t spoil the 3D picture. This effect only plagues monitors with active-shutter glasses which automatically switch to their full brightness in 3D mode.
I don't test monitors using analog interface due to its uselessness for modern computers, but the color temperature settings are disabled on the ZM-M240W when it’s connected via its digital interface. Therefore, we’ve got but one graph here. Fortunately, the monitor is set up well. The average color temperature is just a little lower than the required 6500 K, and the temperature dispersion between the different levels of gray is small.
The monitor’s color gamut is rather a good match for sRGB, surpassing the latter in reds, yellows and greens. It is somewhat smaller than the color gamut of Samsung’s new matrixes with white LED backlight but just excellent for a fluorescent lamp backlight (as a side note, the extended color gamut hype has subsided a little; LCD panel makers now try to cover the sRGB gamut fully rather than to go beyond it, at least in midrange products).
Response time is not a crucial parameter for interlaced 3D imaging as opposed to monitors for active-shutter glasses which have to show left- and right-eye images alternately and without any residue from the previous image. Therefore I did not expect anything special from the ZM-M240W in this respect.
The result is rather discouraging, though. The monitor lacks response time compensation. Its response time average is 16.1 milliseconds (GtG) with a maximum of over 22 milliseconds.
This does not affect the quality of 3D imaging, yet people who buy a modern and expensive gaming monitor may prefer faster products from Samsung, ASUS, ViewSonic and other brands which are also capable of showing 3D images, even though with active-shutter glasses. I guess Zalman should have implemented response time compensation and set it up in a not-very-aggressive way to make the monitor twice as fast as it is.