Using a iMac as a second screen

Please note this advisory on the Luna Display support page—especially point 1 and 2—before deciding:

As have the others, I strongly recommend avoiding pricey workarounds that may require pricey cabling and go for a free-standing external monitor. Life it too short to add more grief.

The following older iMac models can be used as an external display when plugged into another older Mac model.

iMac models introduced in 2011, 2012, 2013, and mid 2014

To use any of these iMac models as an external display:

• The iMac used as a display must have macOS High Sierra or earlier installed.
• The other Mac that you're connecting it to must have been introduced in 2019 or earlier and have macOS Catalina or earlier installed.
• The cable connecting the two Mac computers must be a Thunderbolt or Thunderbolt 2 cable.

24-inch and 27-inch iMac models introduced in 2009 and 2010

To use any of these iMac models as an external display:

• The iMac used as a display must have macOS High Sierra or earlier installed.
• The other Mac that you're connecting it to must have been introduced in 2019 or earlier and have macOS Catalina or earlier installed.
• The cable connecting the two Mac computers must be a Mini DisplayPort cable.

I haven't tried either, but Turn any Mac or iPad into a second display...

https://lunadisplay.com/

Review by NAK005, you may not be happy with it…

Secondary Screen Solution - Apple Community

https://www.duetdisplay.com/

Duet - Remote Desktop, Second Display, Drawing Tablet, and More (duetdisplay.com)

Sorry to tell you but your are wasting your time, Target Display Mode will not work with your computers. Please carefully read Target Display Mode and you will see that.

If you need an external display, please navigate to Amazon.com and search for one, there are scores of them in all price ranges. The advantage over Target Display Mode is:

• Target Display Mode was never a feature it was an accident discovered to work in a few configurations, no not yours.
• Difficult to setup.
• Difficult to maintain.
• Required expensive cabling.

We get your question almost daily on these forums (do a search) and you will see my answer is consistent with what you will read.

Buy an aftermarket external display for the MacBook Air

see > Use an external display with your MacBook Air - Apple Support

Then repurpose, sell, give away or recycle the 2013 model iMac.

see > What to do before you sell, give away, trade in, or recycle your Mac - Apple Support

amaal161 wrote:

PLEASE HELP!!

I am trying to use my iMac late 2013 model to connect to my MacBook Air 2024 as I would like to use the iMac as a second screen. I bought the thunderbolt adapter and cable but when pressing the command + F2 buttons nothing happens. I am not a pro at this at all so any help would be much appreciated. I need to get this sorted out before Monday:(

Your Late 2013 iMac supports Target Display Mode using Thunderbolt input. Much to my surprise, the Technical Specifications for that machine list this as a feature. (Technical Specifications for 27" 2011 and 2012 iMacs don't, which led me to believe that Apple had stopped advertising the feature once it required the use of Thunderbolt.)

iMac (27-inch, Late 2013) - Technical Specifications - Apple Support

Unfortunately, your MacBook Air doesn't support using ANY iMac as a Target Display. You've probably spent $80 on specialized Thunderbolt connection hardware that won't be of much practical use to you.

The MacBook Air is too new to be able to use Target Display Mode. The MBA machine must be a 2019 or earlier machine.

There are some software methods one can try: Luna Display, and Duet. Both are be pricey. With Duet you can get a 30 day demo of it. You may have to install software on both machines and they may be via annual subscription. I've read in other topics here that both can be slow in response time.

It probably would be more cost effective to get a 3rd party monitor for the MacBook Air.