I am going to return this additional 5k display I got and just go an alternate route. I don't really use it in 5k mode, as a side note, either. I can't read the things that small and if I make it bigger, what's the point of 5k?
I don't know what you used for a monitor setup previously, but take a moment to consider something.
My prior setup was a "early 2013 rMBP" with a pair of Apple Cinema Displays, with the ACD on the right in Portrait orientation for reading full pages of scanned documents with nothing cut off and no wasted space compared to Landscape orientation.
With a 27" diagonal screen that has 5,120
physical/actualpixels across the width and 2,880
physical/actual pixels tall on a 16:9 format, you are working with a panel that is displaying content amongst 14,745,600 pixels. This works out to be approximately 217 pixels across any inch that you choose to measure.
To compare to the LG 4K panel at 21.5" diagonal using the "UHD" marketing term for a screen with 4,096 pixels across (as opposed to the literal doubling of an "HD" panel of 1,920 x 1080 pixels which would be 3,840), and 2,304 tall, it appears that the 4K is made from the same format as the 5K monitor as it has a pixel density of 218. Account for marketing measurements and sizes, they are the same screen.
4,096 is 80% of 5,120
2,304 is 80% of 2,880
21.5" is 80% of 27"
Now that your eyes are glazing over, I'll try to wrap this up.
To have two 27" monitors, one with a 5K panel and the other with a 4K panel.
The 5K panel has 14,745,600 pixels in total. 217 ppi (which "becomes Retina" above 16" of distance from the screen)
The 4K panel has 9,437,184 pixels in total. 174 ppi (which "becomes Retina" above 20" of distance from the screen)
That's a difference of 5,308,416 pixels that are working to display the UI content from the computer. This is 36% more pixels packed into the same area.
So to answer your question of "What's the point of 5K if I can't read things that tiny?", we need to clarify the definition of 5K. 5K of
what, specifically.
Notice that Apple altered the menu for Display Preferences a while back, where it used to always show the numerical resolution but now simply shows a box with an example of what text might appear like if you were to choose that setting. This is because it is not correct to identify the differences with a reference to a number of pixels wide and tall. This may have been somewhat appropriate when display technology didn't vary wildly in the number of PPI like it does today.
What a 5K panel at a 16:9 ratio means is that it is approximately 5-Megapixels in width. In our case, the LG 5K monitor can
RESOLVE the display content across all 14,745,600 pixels. If you were to hold down the
OPTION key when clicking on "Scaled" within Display Preferences, you can force it to show you a
numerical representation of what the content sizing should appear like, given that the physical screen size were to remain the same but with different levels of PPI in the panel.
I recall back when printers were marketed as having "300 DPI!" capability. If you took a printer that could do 300 DPI (Dots Per Inch) and another printer with only 150 DPI capability, and printed the same exact image/content, the size of what was printed would remain the same, however the sharpness would be superior on the 300 DPI printer because it was able to
resolve the output with greater resolution. I never heard anyone say that they would rather use a printer with a lower DPI because they weren't able to see the smaller dots of a printer with a higher DPI. The point is that users are not supposed to ever be viewing their computer's content at the native 1:1 resolution that 5K provides.
If you do get a 27" monitor with a 4K panel, please let us know how it works for you. My entire point about my prior monitor setup was that those ACD monitors were 2,560 x 1,440 pixels natively. That native sizing was the smallest that you are able to have the UI be resolved. The LG 5K being able to natively resolve twice as much UI area packed into the same physical width and height means that it can resolve other
virtual resolutions in between these two. Holding the Option Key when clicking on Scaled will show you 2,880 x 1,620 and my personal preference 3,200 x 1,800 sizing. With 3,200 x 1,800 I notice that my need to have the screen rotated 90º is not nearly as imperative as it was with the ACD monitors. I can now view not just one PDF document page, but actually a pair of pages side-by-side. They would be slightly smaller physically in relation to the world around me, but reducing them to this size on a 5K monitor allows the text to remain crisp and not smudged/fuzzy like it would on the ACD. Plus viewing spreadsheets is a much better experience as some that were wide would be display well on a monitor in 90º Portrait orientation, causing me to need to move it to the ACD in Landscape orientation.
I still wouldn't mind an LG 4K hanging off the wall in Portrait orientation as a 3rd display. I wonder if the TB3 controller has enough remaining bandwidth to be able to display a 4K alongside a 5K monitor without forcing the 5K to fake it's output down to 4K and back up to 5K. Maybe we'll find out soon at the Apple Store.
Sigh....so much for "wrapping it up", so here's a lovely photo of when I was able to get 90º rotation enabled on Sierra.
~Scott
