Using an Apple MacBook Pro or iMac as an External Display: Possibilities and Considerations

When it comes to extending your workspace or adding an extra display, the Apple MacBook Pro and iMac offer intriguing possibilities, but the feasibility varies significantly. In this article, we'll explore the options and considerations for using an Apple device as an external display, focusing on the practical steps and technical requirements.

The Limitation of Apple Devices as Monitors

Contrary to popular belief, an Apple MacBook Pro or an iMac cannot be used as a standalone monitor for another computer without significant modifications. These devices are inherently designed as output devices, meaning they are optimized to display content from another computer rather than operate as standalone input devices.

If you are technically adept, it is possible to repurpose these devices at a fundamental level to function as both input and output devices, but doing so poses significant risks and is beyond the scope of typical user capabilities.

In summary, an Apple MacBook Pro or iMac cannot be used as a standalone monitor without modifying the hardware or software, and such modifications are not advised due to potential risks and unreliability.

Using iMacs as External Displays: Practical Steps

However, Apple does provide a solution for using an iMac as an external display, known as Target Display Mode. This feature allows you to extend the display of one Mac to another Mac or an iMac. Here's a detailed guide on how to do it:

Eligibility and Requirements

The iMac used as a display must have macOS High Sierra (10.13.6) or earlier installed. The other Mac that you are connecting it to must have been introduced in 2019 or earlier and have macOS Catalina (10.15.7) or earlier installed. The cable connecting the two Mac computers must be a Thunderbolt or Thunderbolt 2 cable for 27-inch and 24-inch iMacs introduced in 2011 or later. For earlier models, a Mini DisplayPort cable is required.

Using Target Display Mode

Ensure that your iMac is started up and meets the system requirements listed above. Ensure that the other Mac is started up and logged in to a macOS user account. Connect the two computers using the appropriate Mini DisplayPort or Thunderbolt cable. Press Command-F2 on the keyboard of the iMac. You should now see the desktop of the other Mac. To exit Target Display Mode, press Command-F2 again, disconnect the cable, or restart either Mac.

Additional Features and Considerations

Applications that were open on your iMac when entering Target Display Mode remain open in Target Display Mode. For example, if you are playing music on your iMac, the music continues to play on the external display. The other Mac cannot use the iMac's built-in camera or ports. Connect external devices directly to the other Mac, not to your iMac. To control brightness, use the Displays preferences on the other Mac or the brightness keys on the keyboard of the other Mac. To control the sound, choose Apple menu > System Preferences > Sound, and select your iMac as the device for sound output. Use the sound and media keys on the keyboard of the other Mac to adjust volume and control media playback.

What Can Go Wrong

If your iMac does not show the desktop of your other Mac, you can try the following steps first:

Restart your iMac. Restart the other Mac. Unplug the Thunderbolt or Mini DisplayPort cable from the other Mac, then plug it back in. Press Command-F2 on the iMac.

If these steps do not resolve the issue, try the following solutions:

If you are currently logged in to the iMac that you want to use as a display, choose Apple menu > Log Out to return to the login window, then press Command-F2 again. Choose Apple menu > System Preferences, then click Keyboard. If "Use F1 F2 etc. keys as standard function keys" is selected, target display mode uses Command-Fn-F2 instead of Command-F2. It might also help to use the keyboard that came with your iMac. Some third-party keyboards and older Apple keyboards do not support target display mode. Ensure that your iMac is using macOS High Sierra 10.13.6 or earlier. You cannot use target display mode with later versions of macOS or with Boot Camp and Windows.

Conclusion

In conclusion, while using an Apple MacBook Pro or iMac as a standalone monitor requires significant hardware and software modifications, Apple's Target Display Mode offers a practical solution for extending your desktop. By understanding the requirements, steps, and potential issues, you can make the most out of this feature and enhance your productivity.