Originally Posted by Free
Well.. I am no expert, but I think you just put up a 100ire window, and a 0ire window, and measure the difference with a light meter.
Edit: Ooops I see it is a bit more difficult than I thought.
Close but you divide.
Prolem is you'll often run into the limits of a meter there.
1. measure a 100% pattern. For a rough measure, I recommend a window, not full screen, to minimize room effects. OFr a more true measure, maybe a fullscreen will test optics more fully and properly. Position meter so meter is reading near top of its range (i.e close to PJ as possible)
2. Measure a 0% pattern in identical position (tripod)
Divide 2 numbers.
There is a more complicated way to do it with 2 different ranges and combine the 2 readings, for PJ's that are hard to read at #2 above. In that method the sensor is at or very near the PJ lens at the low reading. And it's probably the more accurate way.
If rough dosent' suit, you can get into "ANSI". You do same, then average multiple light/dark readings taken at the same points. See ansi pattern on my calibration DVD for places to measure.
Then there's simultaneous ANSI, which is a different thing. I preger Greg Rogers metod for that one.