The Macbook Air 2018 just serves the purpose of a "reference display" to check the spectrophotometer (Colormunki Photo) against.
Here are its advantages.
1. You have measurements from other people with i1 pros (not display, but the spectrophotometer variant) out there for it ( https://www.notebookcheck.net/Apple-....357481.0.html
They didn't deactivate auto brightness, and therefore got the entirely wrong gamma curve (display adjusted brightness during the measurement) out of it, but you can still use the 100% white point measurement they did.
And that was dE 2000: 0.6 out of the box. In my case as well (in my case 0.3 to 0.6 depending on the probes positioning, max 0.8 when using the default i1d3 white LCD correction profile).
2. It seems to come perfectly calibrated out of the box (power line gamma 2.2 SDR calibration), which means, you take your probes (spectrophotometer, and the colorimeter), make sure to set pattern color range to 0-255, disable auto brightness (monitor settings in Macos), make sure the default color profile is active (monitor settings in Macos), and tick brightness to 100 nits (press minus screen brightness key on the laptop until the screen turns off, then plus brightness for 10 ticks, plus two option+shift brightness up (fine adjustment) ticks.
At that point you should have a display with 'perfect' greyscale, perfect gamma (for most of the line), perfect brightness curve. At least in theory (factory variance).
3. It is a white LED LCD, so "pretty standard" in terms of technology and color range (99% standard color gamut), thats why you can use it for testing your i1d3 (from now on I'm using the abbrevation, because its easier to type..
its the i1 Display Pro) in white LED LCD mode (close to its default capabilities) as well.
In theory - even though "multi factor" of stuff that can go wrong, all those aspects should line up pretty well, with what your Colormunki Photo and i1d3 are measuring.
Here is the short version of why we do it: You take a display thats pretty much perfectly calibrated out of the box, and you use that to check how accurate the meters you just bought are. That the Macbook Air 2018's display is pretty "standard" by all aspects (nothing fancy - see spectral graph above) helps in that regard.
Now - this is one display (tech). So if those values line up pretty well for you - next step would be to test the i1d3 with zoyds WRGB OLED correction in HCFR on a LG OLED, and compare it to the Colormunki Photo readings on that device. The results shouldnt differ by more than 0.5 dE 2000 on white ideally (thats the difference in my case).
This step basically is used, to get an idea of how your two meters behave on a different screen technology.
0.5 dE 2000 difference could be introduced by the fact, that .ccss corrections (the correction zoyd provides in HCFR for the i1d3 and WRGB OLED screens) arent that accurate fore example, so we dont know where its coming from. But the fact, that this is very low as well - on a different screen technology, with zoyd using entirely different meters. Is encouraging.
That whole thing is there to basically give you confidence in your meters.
Because thats mostly whats being sold at higher pricepoints. Confidence in your meter. (Inter meter variability out of the factory gets lower.)
We try to sidestep that by putting multiple factors of uncertainty together, and still ending up with only small error margins. Ideally.
Thats basically "not paying for a recalibration of your meter".
The i1d3 and the Colormunki Photo in practice also dont seem to drift very much. The i1d3 simply because it doesnt. The Colormunki Photo, probably because it has a recalibration process (it meassuring a white ceramic tile) built in it - and that seems to work quite well even after 5 years of use on the meter - at least in my case.
This is also "not paying for a recalibration of your meter".
Why am I using a Macbook Air 2018 and an LG OLED TV for this suggested method?
Because they are widely available to any calibration enthusiast. At least in theory. Available to borrow even.
In the case of the Macbook Air 2018 you have basically a perfectly calibrated display out of the box. With the brand Apple attached to it (people believe in that..
With the LG OLED TV and HCFR you have zoyds .ccss correction done with a Jeti spectrometer (the best of the best), towards his i1d3 probe. 0.5 dE 2000 towards your i1d3 vs Colormunki Photo is still comparatively small - all things considered. (Ideal outcome "hey, they dont differ by much" thought in your mind).
Thats all that the Macbook Air 2018 and the LG OLED are for.
For calibration itself - you can use, own or buy any laptop - it doesnt matter.
For "verification" of your meters I encourage you to "borrow" or get access to those devices, after you've bought the meters (probably used in some cases.).
Macbook Air 2018 display may drift over time, I'll look at that as well.
Currently I use it for about a month, and to everything I have at hand - it measures "reference quality" (even in colors, but that doesnt matter so much for our purposes), maybe apart from blacklevel, but we arent so much interested in that...