The difference that matters
The Optoma ZK431ST-B is brighter (4,100 lumens against 3,000). 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 BenQ AH30ST costs $300 less at the prices we observed.
Side by side
| Specification | BenQ AH30ST | Optoma ZK431ST-B |
|---|---|---|
| Brightness | 3,000 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 | 27 fL | 37 fL |
| Light source | Laser | Laser |
| Rated life | 20,000 h | 30,000 h |
| Zoom | 1.2× | Fixed |
| Lens shift | — | — |
| Input lag | About 16.7 ms (game mode) | 16.7 ms (4K 60 Hz); 8.6 ms (1080p 120 Hz) |
| Price seen | $1,499 | $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?
Optoma ZK431ST-B
Choose the Optoma ZK431ST-B if your room has ambient light or a large screen or you need to mount it close to the screen.
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