5K users: 4K secondary a distraction?

Discussion in 'iMac' started by Ledgem, Jun 10, 2018.

  1. Ledgem macrumors 68000


    Jan 18, 2008
    Hawaii, USA
    Hi all,

    I have a 5K "retina" 27" iMac that I have greatly enjoyed using. I'll be away for work for about a year with my MacBook, and will be leaving the iMac at home. To mitigate the pain of going to the 12" MacBook screen as my main computer, I was considering getting a 27" display for the year, and then bringing it home afterward... as I had been wanting to get a second display for the iMac, anyway.

    The trouble is, the MacBook can't drive anything higher than 4K.

    My question is, has anyone used the 5K iMac with a 27" 4K display, and if so, is it very noticeable and the external display isn't 5K? I'd guess that it'd be difficult to tell at a glance, although windows would resize between the two displays which could be a nuisance. Any thoughts?
  2. pier macrumors 6502a


    Feb 7, 2009
    I've used a 4K 24'' monitor alongside the 5K iMac. It was perfectly fine.

    In your case (4K 27'') I doubt the change in DPI is going to be much of a problem, but the change in text size might be annoying depending on your use. I doubt it though, but this is a very subjective thing.
  3. pubmsu macrumors regular

    Dec 9, 2014
    Sydney, Australia
    Between your iMac 5K and the 4K, is the difference in text sharpness/crispness noticeable from normal viewing distance of 2 feet?
  4. jmiddel macrumors regular

    Mar 3, 2010
    Land of Enchantment
  5. theluggage macrumors 68040

    Jul 29, 2011
    That depends on what scale you run the 4k screen at. The default 4k native "looks like 3840x2160" mode makes everything rather too small to be usable (unless you're a young whipper-snapper with perfect eyesight) and the efficient pixel-doubled "looks like 1920x1080" mode makes everything a bit too big at 27".

    However, you can choose the "Looks like 2560x1440" scaled mode that makes everything exactly the same size as on a 5k iMac in its default mode. What you're effectively seeing is a an internal 5k screen image down-sampled to 4k. This comes with a couple of caveats:
    • Its more CPU/GPU-intensive than either 4k native mode or pixel-doubled mode - but a recent iMac can eat that for breakfast
    • Because its scaled at a non-integer ratio, there is a slight soft/anti-aliased effect on text and icons that you'll see if you look closely - but its still pretty darned sharp.
    ...but overall I'd say its the perfect mode to use, and it takes seconds to switch to a different mode if that suits a particular job. Certainly forget any bad experiences you've had running standard-res displays at non-native resolution - "scaled mode" on retina/4k/5k displays is completely different.

    Anyway, "distracting" is completely subjective. I've currently got a (cheap) 4k 28" next to my 5k iMac and the difference is clearly there if you go looking, but the 4k is still nice and sharp and it certainly doesn't jump out and hit you. What is more obvious is that the colour/brightness/contrast on the screens doesn't really match and - since the newer iMacs have a P3 wide-gamut, extra bright display they're never going to match a standard-gamut external display.

    One other thing: remember that there's no height adjustment on the iMac, so unless you want to start propping things up on books, make sure that any second display you buy does have height adjustment so you can line it up with the iMac display.

    NB: I'm not actually sure that a 27" 16:9 widescreen display is the best choice for a secondary monitor for an iMac - the far edge of that second screen gets a looong way away from where you're sitting and starts to gather virtual cobwebs... In the days of standard res I'd have gone for a 24" 1920x1200 as a secondary but, unfortunately, the free market means 50 brands of cola and no ginger beer, so there don't seem to be any 16:10 or 4:3 screens around (outside of MBPs and MS Surface machines).
  6. Fishrrman macrumors P6


    Feb 20, 2009
    Get a decent 4k display.
    It doesn't have to be the LG/Apple, in fact I recommend that you get something else.

    For a year it will be fine.
    I predict that even after you bring it home and connect it to the iMac, it will still be fine...

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