Originally Posted by Kris Deering
I definitely agree with them about light in regards to 3D. Just measuring through the glasses is not going to be accurate because the meter is averaging the data and depending on the condition during the average the light measured isn't going to represent what you see with your eyes (which shouldn't see the black frames in between). I've done my initial rough calibration for 3D through the glasses and it turns out pretty well. I've been thinking about different ways to do it though and I'm still mulling it over. Maybe an offset for the glasses so you can measure without them would be one way. I am going to talk with the Spectracal guys and see if they have any ideas.
The recommended way is to either profile your colorimeter without the glasses to your spectro through the glasses, and then use the colorimeter without the glasses for the actual calibration, or if you don't have a spectro/meter combo to profile your meter without the glasses (field) to your meter with the glasses (reference), so that again you can do the calibration without the glasses to avoid interference from the shutters, especially when reading low light patterns like dark blue or the low end of the greyscale.
What I do as well is I set the LLH for the meters with the threshold to a very high value during the profiling, that way each offset will be the result of an averaging and should limit the influence of the shutters during the profiling. For example, for the i1pro, enable LLH and instead of using a threshold of 10cd/m2, use a threshold of 150. That way, LLH will be active even when measuring 100% white, not only when measuring the darkest patterns, and each offset for each color will be averaging the max number of samples (I think it's 30 for the i1pro/i1pro2).
This trick of using LLH with a very high threshold is good even when profiling your meters for 2D, it just gives the profile an extra bit of accuracy.
Of course only do this during the profiling, after that restore the LLH threshold to its normal value (or disable it) otherwise the calibration will be super slow.
One last trick when profiling is to make sure you open the iris to the max and switch to high lamp. Even if you lower your iris / switch to low lamp during calibration, this will give optimum accuracy to the profile when reading through the glasses, otherwise it can struggle with blue/magenta.
This produces excellent results, and very repeatable/accurate, in both 2D and 3D (well, with different profiles of course!)