Originally Posted by skschatzman
This brings me to my next topic. I have read many different topics on meter read distance. I have read some documentation that the meter direct contact. I have also read and have been suggested to use distance measurements. I can't find much as far as definitive documents or information on which method should be used for different situations.
Mounting the i1Display PRO/C6 (it's a branded OEM i1Display PRO) or i1PRO1/2 to an any display is not a good idea, it's better to use the tripod mount and take only non-contact measurements.
If such contact devices are used, it can be important to assure that they are touching the screen lightly enough to avoid any changes in the measurement results from mechanical contact. i1PRO's are heavy for contact measurements, you have a very small FOV when they measure in contact mode.
EBU TECH.3325 Publication (Methods for the Measurement of the performance of Studio Monitors) recommends the distance measuring geometry rather than the contact method.
If you have 10cm distance (or larger) from the panel it will be good, we don't need the panel to transfer it's heat to the meter.
Meters will require to be connected/powered from their USB plug for about 20-30 minutes before starting any measurement. The exact time depends from the temperature conditions. It can be longer if the device came from outside in winter time and will be shorter if stored at room temperature.
Usually users confuse warmup procedure and leave the meter on-contact with the display panel to become warmer from display's panel heat, which is a bad idea.
The meter must be at the room temperature, when the meter has stable temperature it will provide stable readings over the time, heat is not good for the sensors, when the meter is becoming warm, more noise is added to the sensor and this reduce the instrument S/N ratio.
Light emitted from displays is a electromagnetic radiation which will alter the temperature of the detection system of a meter, so the sensors themselves will heat up, one reason why meters like i1PRO1/2 require dark readings; to lower the drift caused by heat.
i1PRO2 has better thermal isolation due to its aluminum at the side. i1Display PRO using robust filters against prolonged exposure to heat.
basICColor DISCUS has aluminum unibody for added robustness and thermal stability and also features internal thermal compensating circuitry which will ensure that changes in the physical temperature around the device will not influence measurement results.
Konica-Minolta CS-2000 features a peltier thermo-electric cooling system to reduce dark current and improve S/N ratio.
If you check JETI, PhotoResearch,Minolta, reference meters, none of them is measuring in contact mode.
Hi-end spectro's with 1/2° can't measure in contact mode without specific accessory attached.
For example Minolta CS-2000A min. measuring meter placement distance is 35cm (or 5,5 cm when using close-up lens).
-680 needs 10 foot (3.05 m) long probe designed for contact measurements of luminance to provide 13.2 mm measuring area.
For example, my Klein K-10A without any accessory attached, with 10cm distance from the panel it measures an area of 5cm (FOV), to measure the same area with my JETI 1211, I have to place it with 161cm from the panel.
JETI 1211 has 1.8° FOV and is closer to SMPTE recommendation from any other instrument.
SMPTE recommends to take readings from the viewing position, but that's is not possible for the consumer probes, you need an instrument with ~2.0° field of view.
Also there some published documents that suggesting to measure about 100 pixels minimum for display calibration which is not possible for some meter in contact mode.
A high-end spectro with a viewing optics (like PhotoResearch or Minolta) or with laser aiming (like JETI) with narrow viewing angle for this job.
As you can see from the following Chart (created by <^..^>Smokey Joe), the JETI (1.8°) is closer to SMPTE recommendation from any other instrument.
Each meter's optics have its' own FOV (Field of View), 2 meters with the same distance from the screen, they see different area of pixels.
If someone has both meters (i1DisplayPRO - i1PRO1/2) and he want to match the meters measuring pixel area (FOV), for an area of pixels of 25mm diameter, for i1PRO1/2 need to have 17,8cm distance from the screen and the i1DisplayPRO to have 13,6cm distance from the screen. You can do the calculations for different distances from your screen.
FOV is important for displays that have uniformity issues, so it's better to measure the same spot when you do your meter profiling.
You can find a lot of details about your X-Rite instruments here
. (+ tips for meter correction table creation)