Universal Control and Extended display to Middle Aged iMacs.

It would seem that my new 2021 MBP and universal control is quite capable, however extending the display to my late 2015 iMac to use it as a secondary 5k display is still not a reality.

I have understood that this has never been possible before, but with the new universal control feature, it really sounded like it was going to be. Alas, I still cannot use the iMac as an extended display from the new MacBook Pro.

Will this continue to always be impossible? Will this be a possibility once universal control is out of BETA status? Seeing how this can be accomplished by other means, sure seems like this limitation is a choice by the developers and not an insurmountable limitation of old designs being incapable of new tasks...

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Darnell_Jones
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i was very disappointed i couldn't extend to the iMac. the other way around (iMac to MacBook) is pretty useless. I don't need my slower computer with the big screen to show up all tiny on my faster computer that i can't use.

Posted by
artecolote
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  • You can get it to work with OCLP - google it. I have it working on a mac from 2011. I also tried on iMac 27" 5K and i works.

    —
    fugzao
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Universal Control document, including "Supported Devices":
https://support.apple.com/en-us/HT212757

Specifically:

  • iMac introduced in 2017 or later, plus iMac (Retina 5K, 27-inch, Late 2015)

extending the display to my late 2015 iMac to use it as a secondary 5k display is still not a reality.

It sounds like this should work...
...so it might be worth double-checking that everything is set up correctly (as explained in that same link).

Posted by
robnotyou
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  • (I may have misunderstood your question?)

    —
    robnotyou

  • I think you are understanding my question just fine.

    I read that page and double checked everything, restarted everything etc etc. I thank you for that, although it didn't change anything.

    Universal control itself is working like gangbusters except for this one thing.

    On the iMac : In Display settings : Select the MBP : In the drop down menu for "Use As" you can select "Use as mirrored or extended display" and then that works, i am mirroring the iMac screen to the MBP

    On the MBP follow same steps: only option for the iMac is to use as Linked Keyboard and mouse. The option to use as Main Display or mirror or extend isn't there.

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    Darnell_Jones
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Interestingly, the list of iMacs that can connect to the new Studio Display includes the "2017 or later", but not your "Retina 5K, 27-inch, Late 2015". I wonder if this might be related, and the "Late 2015" is missing something critical?

Posted by
robnotyou
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  • Well... if I had a studio display I would be using it with the MBP, not the 2015 Mac. Just the same, yes, they seem to want to cause us to believe that it's got a hardware deficiency somewhere. However, I don't believe it: aftermarket products make it work! Luna Display promises this function. Just not quite at full pop. It'll do 5k @ 45htz instead of 60. But will do 4k at 60... I find it so very hard to believe that we can repurpose 30 year old satellites that are speeding around at thousands of miles per second millions of miles away to do things they were never intended to do... but my old desktop monitor is obsolete. This is most likely Apple style marketing (but I really hope its not, and hope they are done with childish things like intentionally killing battery life to make you upgrade phones). Waiting patiently to see if they intend for this to work and I am doing something wrong or if, since still in BETA there is a glitch somewhere. Yes, I could sell the old iMac and drop more coin on the Studio Display, but the old iMac won't fetch much I suspect, and I'll still be out another $1,000.

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    Darnell_Jones
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