iMac as monitor for Mac Studio

No.

Nor would you want to even if it were possible. The 2009 iMac has a limited resolution compared to what the Mac Studio can deliver and would majorly hinder the work if dealing with high resolution videos and photos.

Mac Studio: 6K (6144 x 3160)

2009 27 iMac: 2K (2560x1440)

In reality, if you can work with the iMac's resolution, then the Mac Studio is overkill. If you need the Mac Studio, then then limited resolution of the iMac simply won't cut it.

abestrat wrote:

Thanks Phil0124. I also have a late 2014 iMac 27 with 5K resolution ... but I've been told that is incompatible to connect to my Mac Studio. Is that right or is there a way to use the 2014 iMac? thanks.

No.

A pre-Retina iMac operating in Target Display Mode cannot be a display for any Mac from 2020 or newer.

A Retina-class iMac (from late 2014, and newer) does not support Target Display Mode.

Details: Use your iMac as a display with target display mode - Apple Support

Your equipment is too new. Support for this feature has been discontinued in recent Macs:

• 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.

from:

Use your iMac as a display with target display mode - Apple Support

Yes but the Apple article says that to use the older iMacs with the displayport connection, the source Mac has to: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 {one being used as display} 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.

The Studio can't run Catalina. When I use terminal to look for macOS full installers it report 12.3 and 12.3.1 only which mean it can run earlier than 12.3.

Has anyone test it with the source running a macOS version later than Catalina?

It may work on an Intel Mac but that does not say it will work with an M1 Mac.

Malcolm J. Rayfield wrote:

It should work with 24-inch and 27-inch iMac models introduced in 2009 and 2010 with macOS High Sierra or earlier installed.

They use Mini DisplayPort.

It's officially not supported but should work. The 2009 iMac does not use Thunderbolt, and when in Target Display Mode acts just like a Mini DisplayPort display. Unlike Thunderbolt iMacs, they don't need special support on the other computer, so the version of Mac OS that's on the Mac Studio shouldn't matter.

You will get only 2560 × 1440. You will need a USB-C to Mini DisplayPort Cable from one of the Mac Studio Thunderbolt ports.

mophie USB-C Cable with Mini DisplayPort Connector - Apple

A Thunderbolt 3 to Thunderbolt 2 cable won't work even though the plugs will fit.

I know that's what the Apple support article says, but the Mac OS version requirement for the source Mac doesn't seem to apply if the iMac is 2009 or 2010. There are reports in these forums of 2009 or 2010 iMacs working as displays with Macs running macOS newer than Catalina.

Even though it works, the picture on a low resolution iMac may not look as sharp as expected since newer versions of macOS nio longer use sub-pixel antialiasing.

Nope. The 5K iMac while a better and more capable screen, still cannot be used as a display for the Mac Studio.

The Target Display support was dropped for retina Macs, and the new wireless AirPlay to Mac option requires a 2019 or later iMac.

It should work with 24-inch and 27-inch iMac models introduced in 2009 and 2010 with macOS High Sierra or earlier installed.

They use Mini DisplayPort.

Thanks fo that Malcolm J Rayfield!

Your more nuanced explanation helps explain why some users have insisted certain setups work, even though officially "not supported".

If I am hearing you right, the 2009 and 2010 model iMacs with DisplayPort connection are still possible with DisplayPort adapter from USB-C ports.

There's always the option of buying 3rd party displays. Which will in most cases be cheaper and better than the Studio Display.

Look at BenQ, LG and Asus, even Samsung.

https://petapixel.com/best-alternatives-apple-studio-display/

The Studio Display is just a middle or the road, yet only just capable option with an unjustified price tag.