SecondGlowComparison · checked on 13 November 2026
SecondGlow vs Luna Display for a 5K iMac
Both turn an iMac into a display for another Mac. Luna Display is a hardware unit plus an app and works with many Macs and PCs. SecondGlow is software only, made for one job: a 27-inch 5K iMac as a display for an Apple silicon Mac.
Choose Luna Display if you want wireless, use a PC or an Intel Mac, or have an iMac older than 2015.
Choose SecondGlow if you have an Apple silicon Mac and a 2015 to 2020 5K iMac, and want sharp 5K over one cable with no extra hardware, for less than half the price.
| SecondGlow | Luna Display | |
|---|---|---|
| Price | $39 once | $89.99 once, hardware unit included (source) |
| Hardware | None. One USB cable | Luna unit required for every connection (source) |
| Main computer | Mac with Apple silicon, macOS Ventura or later | Mac with USB-C, or a PC; macOS 10.13 or later (source) |
| iMac as display | Retina iMac, 2015 to 2020 (27-inch 5K or 21.5-inch 4K), macOS Monterey or later | Any Mac from 2011 or newer, macOS 10.13 or later (source) |
| Connection | One cable: USB-C to USB-A (USB 3), or Thunderbolt on 2017 and later iMacs | Wi-Fi, Ethernet, Thunderbolt or USB (source) |
| 5K on a Mac | Native 5120 × 2880. About 50 to 60 fps on full-screen video over USB 3, measured by me | 5K at 45 Hz or 30 Hz; 4K at 60 Hz. 5K needs the USB-C unit and Big Sur (source) |
| Sound on the iMac | Yes, on macOS Sonoma 14.2 or later | No, sound plays from the main computer (source) |
| Free trial | 7 days, no card | Not stated on the pages checked |
Where Luna Display is better
- Many more Macs. Any Mac from 2011 can be the display, so it covers the 2014 iMac and older non-5K iMacs, and Intel Macs can be the main computer.
- Wireless. It works over Wi-Fi as well as cables.
- PCs. A Windows PC can be the main computer.
- A long track record from an established company.
Where SecondGlow is better
- Nothing to plug in but a cable. No hardware unit to buy or lose.
- Price. $39 instead of $89.99, with a 7-day free trial before you pay.
- Sound through the iMac’s speakers, with your volume keys. Luna leaves sound on the main computer.
- Made for the 5K iMac. Native 5120 × 2880, compressed on the GPU so text stays sharp. Luna’s support page lists 5K at 45 Hz on a Mac; I haven’t measured Luna myself.
Which should you choose?
If your main computer is an Apple silicon Mac and your iMac is a 2015 to 2020 5K model, try SecondGlow free first: if it works on your desk, it costs less and needs no extra hardware. If you want wireless, use an Intel Mac or a PC, or have an older iMac, Luna Display is the better fit.
Still deciding? Every way to use a 5K iMac as a monitor, including free options.
Sources
Checked on 13 November 2026, on each product’s own site. Prices and features change; follow the links for today’s details.