Using 2017 iMac as display for M series MacBook

[M.Chapman]

My 2017 iMac is beginning to show its age performance wise versus the new M series Macs, but the 27" Retina screen is still great. So I'm starting to contemplate updating my system and wondering if I can use my iMac as a screen for a new M series MacBook. From what I understand, target display mode is no longer supported, but I came across the Astropad Luna Display and also Duet Display as a possible workarounds. Anyone have any experience of these?

https://www.youtube.com/watch?v=Uau3wmvE_FM

 

Mark

Edited March 31 by M.Chapman

[StokeCreative]

Funnily enough I've been looking at this as well. The loft has a number of imacs from through the years going back to the first Bondi imac.

I think its only a small subset of imacs that can be used as an external monitor, and then I think with a much older operating system on the host computer. Sorry I havent got any more info as I was starting to go around in circles, (and ended up taking out an already upgraded 2Tb disk from an early 27incher to use as a spare external hard drive. I thought about splitting for parts, but I dint think its worth the hassle!

Hugh

[StokeCreative]

Just now, StokeCreative said:

Funnily enough I've been looking at this as well. The loft has a number of imacs from through the years going back to the first Bondi imac.

I think its only a small subset of imacs that can be used as an external monitor, and then I think with a much older operating system on the host computer. Sorry I havent got any more info as I was starting to go around in circles, (and ended up taking out an already upgraded 2Tb disk from an early 27incher to use as a spare external hard drive. I thought about splitting for parts, but I dint think its worth the hassle!

Hugh

Of course everything is being diligently photographed so you never know.....

 

[M.Chapman]

Even more adventurous option here.

https://www.cultofmac.com/774780/clever-diy-projects-hacks-old-imac-into-a-studio-display/

 

Mark

[Cal]

I think you might be able to get it to work with OpenCore Legacy Patcher, or by simply wiping the Mac and reinstalling High Sierra (they removed target display mode in later versions).

[M.Chapman]

1 hour ago, Cal said:

I think you might be able to get it to work with OpenCore Legacy Patcher, or by simply wiping the Mac and reinstalling High Sierra (they removed target display mode in later versions).

From what I've read, in the case of 2017 iMacs it also coincides with a hardware change (Retina display) as Apple never wrote the new code required to support target display mode on iMacs with Retina displays.

 

Mark

Edited December 22, 2023 by M.Chapman

[M.Chapman]

On 22/12/2023 at 11:42, Cal said:

I think you might be able to get it to work with OpenCore Legacy Patcher, or by simply wiping the Mac and reinstalling High Sierra (they removed target display mode in later versions).

Target display mode is not available on 2017 5K Retina iMacs (whatever the MacOS).

 

But, thanks to your advice, I have managed to get Air Display mode working via a Thunderbolt cable using OpenCore Legacy Patcher (OCLP). Turned out to be much easier than I expected. Basically OCLP can add Air Display mode capability for Macs that don't normally support it, so now my 2017 5K Retina iMac running Ventura can function as a second or mirrored display for my MacBook Air. I didn't need to reinstall a patched MacOS or anything complicated, I just needed a tiny USB memory stick that the system pre-boots from, before continuing to boot from my normal drive containing MacOS. It takes about 10 minutes to set up. If I want to revert back to my old setup I can simply shut down, unplug the USB drive from my iMac and then reboot.

 

But... although Air Display mode is relatively fast and almost lag free, there's clearly some scaling and/or compression going on. PS running on my MacBook Air and then mirrored (or moved onto a second display) via Air Display using my iMac doesn't appear as sharp as PS running natively on my iMac. I've tried every setting, but can't get the quality I'm used to. It's as if my iMac is being supplied with a 2560 x 1440 signal rather than 5120 x 2880. So, although it provides a 27" display capability, it doesn't provide "Retina" quality. 

 

Nevertheless, if anyone wants to know how to setup Air Display mode on an iMac that doesn't support it, let me know and I'll post instructions here. There are lots of helpful videos on Youtube, but the ones I found referred to an old version of OCLP. The new version of OCLP makes it very easy (once the right setting boxes are ticked).

 

I'm also going to see if I can get hold of an Astropad Luna adaptor to see if that's any better.

 

Why am I doing this? Because I really like my iMac 27" 5K Retina display, but need to update to an M series Mac (probably a Mini). The Apple Studio display is so expensive, so I'm looking at alternatives. If I can get my existing iMac to work as a display that would be great. If not I'll have to get a 27" 5K Benq or LG instead, but IMO they aren't as nice as the iMac.

 

Mark

Edited April 1 by M.Chapman

[Cal]

On 31/03/2024 at 09:33, M.Chapman said:

Target display mode is not available on 2017 5K Retina iMacs (whatever the MacOS).

 

But, thanks to your advice, I have managed to get Air Display mode working via a Thunderbolt cable using OpenCore Legacy Patcher (OCLP). Turned out to be much easier than I expected. Basically OCLP can add Air Display mode capability for Macs that don't normally support it, so now my 2017 5K Retina iMac running Ventura can function as a second or mirrored display for my MacBook Air. I didn't need to reinstall a patched MacOS or anything complicated, I just needed a tiny USB memory stick that the system pre-boots from, before continuing to boot from my normal drive containing MacOS. It takes about 10 minutes to set up. If I want to revert back to my old setup I can simply shut down, unplug the USB drive from my iMac and then reboot.

 

But... although Air Display mode is relatively fast and almost lag free, there's clearly some scaling and/or compression going on. PS running on my MacBook Air and then mirrored (or moved onto a second display) via Air Display using my iMac doesn't appear as sharp as PS running natively on my iMac. I've tried every setting, but can't get the quality I'm used to. It's as if my iMac is being supplied with a 2560 x 1440 signal rather than 5120 x 2880. So, although it provides a 27" display capability, it doesn't provide "Retina" quality. 

 

Nevertheless, if anyone wants to know how to setup Air Display mode on an iMac that doesn't support it, let me know and I'll post instructions here. There are lots of helpful videos on Youtube, but the ones I found referred to an old version of OCLP. The new version of OCLP makes it very easy (once the right setting boxes are ticked).

 

I'm also going to see if I can get hold of an Astropad Luna adaptor to see if that's any better.

 

Why am I doing this? Because I really like my iMac 27" 5K Retina display, but need to update to an M series Mac (probably a Mini). The Apple Studio display is so expensive, so I'm looking at alternatives. If I can get my existing iMac to work as a display that would be great. If not I'll have to get a 27" 5K Benq or LG instead, but IMO they aren't as nice as the iMac.

 

Mark

 

The instructions could be useful, I'd be interested to see what/how you did it, for future reference.

 

I plan to run my 27" iMac potentially well into obsolescence (already booting off an external SSD) but one day I'll eventually cave and upgrade but I'd love to be able to continue using it as a display. There is a huge gap in Apple's lineup at the moment and a Mac Studio + Studio display just isn't it. I really hope they see sense and introduce a worthy successor, but I suspect it'll be unjustifiably expensive as a result of our ever weakening currency.

[M.Chapman]

14 hours ago, Cal said:

The instructions could be useful, I'd be interested to see what/how you did it, for future reference.

 

Here's what I did on my 2017 iMac which has Ventura 13.6.3 installed.

 

· Use MacOS Disk Utility (View>Show All Devices) to format a small* USB thumbdrive as Mac OS format (Journaled) with GUID partition map. (*1GB is fine, but could be much smaller, possibly only 256MB?)

· Download OCLP app from GitHub, Virus check it (I used VirusTotal) and then Unzip. I used Version 1.4.3
https://github.com/dortania/OpenCore-Legacy-Patcher/releases/download/1.4.3/OpenCore-Patcher-GUI.app.zip

· Open OCLP app and on the opening / home Screen) screen, click Settings button

· Build Tab - Show Open Core Boot Picker - Untick (if you only boot from 1 drive, or set 10 seconds delay if you’d need to choose between boot drives).

· App Tab - Allow Native Models - Tick

· On OCLP Home screen, click Build and Install OpenCore

· Click Install to disk and select the USB thumbdrive to put the EFI boot loader on.

· Reboot the Mac whilst holding Option Key (to allow boot disk selection)

· Select EFI boot on USB thumbdrive as the disk to boot from

· Mac appears to boot normally but with OCLP patches from EFI boot loader applied (NB. If need to change which drive to boot from next - if no 10 sec delay was set, hold Escape key while booting. To set as default select new boot drive and type Cntrl Enter)

· iMac will now allow Air Play and will iMac appear as available display on other Air Play compatible devices (Use Toggle slider button icon on top menu bar).

· Connect devices via Thunderbolt or Ethernet cable for (almost) lag free operation.

· To remove patches, simply shut down, unplug USB thumbdrive drive, and then reboot or select normal boot disk in System Settings>Startup disk and then reboot. 

 

The Youtube video that helped me work out what to do is here https://youtu.be/sO0yc3_hOE8 but it covers Monterey and an old version of OCLP that's no longer used. The new version is much easier to use.

 

Hope that helps. 

 

Mark

Edited April 2 by M.Chapman