The Optoma ZK431ST-B throws a given image from closer (ratio 0.496 against 0.69). The Optoma ZK431ST-B lists higher resolution (4K UHD). The Optoma ZK431ST-B uses a laser light source; the other uses a lamp. The Optoma ZK431ST-B costs $200 less at the prices we observed.
Side by side
| Specification | BenQ AH500ST | Optoma ZK431ST-B |
|---|---|---|
| Brightness | 4,000 lm | 4,100 lm |
| Resolution | Full HD 1080p (1920 × 1080) | 4K UHD (3840 × 2160) |
| Native aspect | 16:9 | 16:9 |
| Throw ratio | 0.69–0.83:1 | 0.496:1 |
| Distance for a 10.5 × 8 ft 4:3 screen | 9′ 8″ | 6′ 11″ |
| Brightness on that screen | 36 fL | 37 fL |
| Light source | Lamp | Laser |
| Rated life | 15,000 h | 30,000 h |
| Zoom | 1.2× | Fixed |
| Lens shift | — | — |
| Input lag | About 16 ms (fast mode) | 16.7 ms (4K 60 Hz); 8.6 ms (1080p 120 Hz) |
| Price seen | $1,999 | $1,799 |
Highlighted rows differ. Figures come from each product's sources; room depth, distances and brightness are FOREference calculations using the same method for both.
Which should you choose?
BenQ AH500ST
Choose the BenQ AH500ST if you prefer its maker, seller or ecosystem — the published figures do not favour it.
Optoma ZK431ST-B
Choose the Optoma ZK431ST-B if you need to mount it close to the screen or image detail matters most.
Before you buy either
- Check the room: room size calculator and ceiling height calculator.
- Confirm what each seller includes — accessories, software trials and bundles change often.
- Read the limitations on each full reference page.
FOREference compares published specifications; we have not tested these products side by side. How we work · Disclosure