Originally Posted by Doug Blackburn
If you are trying to match printer output to a CRT or flat-screen computer monitor, you need the graphics version of the meter... but absolutely make sure it is still capable of calibrati8ng a projector.
One of the problems with inexpensive meters is that many of them cannot read light (effectively) when it is reflected from a projection screen. You must turn the meter so that it is measuring the light from the projector BEFORE it gets to the screen. This is a major problem for home projector calibration because the screen itself affects calibration. Some screens actually change the color balance of the reflected light... so if the projector is calibrated perfectly, and you use a screen that shifts color a little, what you are seeing will be a color-shifted version of the accurate projector. So you want a meter that will read light directly from the projection screen and be reliable about it.
Projection screens are also overall, darker than CRTs or flat panel displays so you need a meter that is good (and relatively fast) when measuring the darker end of the luminance scale so you aren't waiting around forever each time you measure 10% white. Many inexpensive meters have fairly poor low light performance.
Finally, any colorimeter you purchase will degrade with time... it is an inevitable outcome. The filters inside the meter change as they age and you cannot stop it (low humidity, darkness, and cool temperatures can slow the process, but it cannot be stopped). So if you want a meter that will be useful over the long haul and not have to be replaced every 3-5 years, you need to be sure that you purchase a meter that can be recalibrated... many, probably most, low cost meters cannot be recalibrated.
There is also something called meter profiling where you measure something with a highly accurate (and expensive meter) and you measure the same something with the inexpensive meter and a correction table is created to make the inexpensive meter's readings more like the readings of the expensive reference meter. Some companies may offer this service for a fee... it is a way of extending the life of an inexpensive meter before it needs to be recalibrated.
All these issues are among the reasons people hire professional calibrators... they maintain their instruments and generally use higher-end meters that the DIY person is likely to be using.
Just in case you're having trouble reading between the lines... you are being steered away from the Spyder series meters for very good reasons. Just because a meter exists doesn't mean it is useful/usable for every/any application.