As I mentioned, it correlates better with my iSis Rev E, the Rev E is different (newer) than previous iSis units. So in that respect, I’m happy. Without a higher end reference Spectrophotometer (who’s qualities are similar in terms of the M series and so forth), and a larger sample of units to compare, we are just guessing here. I really don’t think we need to spend much time discussing how many deltaE values can dance on the head of this pin.
It would be useful to trend how the device measures the same data over time!
The thing to consider is that multiple devices using differing technologies in no why guarantee the measurements are ‘right’. Take the iSis. I have both a Rev C and Rev E. Both produce excellent quality profiles. X-Rite changed the insides of the unit for the Rev E, presumably to improve it and better deal with the new XRGA ‘standards’ which is a good thing. It behaves differently than the Rev C. The max delta’s are about 1 and change or so, nothing earth shattering. Point is, which is ‘better’? Which do we use to say ‘this is the correct, standard measurement’? For those of us that track things like press variation over time, using the same instrument, when something new comes along (say our Rev C needs service or we need to add another iSis), this can cause some issues in the trending of the data. For other users, it isn’t a factor.
What X-Rite is trying to do, and I commend them for it, is making a process that draws a line in the sand in terms of how these various devices behave and thus correlate. A lot of users don’t recognize that a Spectrophotometer made from company A and one from company B don’t have to behave the same (hence the idea around XRGA and some of the M series standards).