The difference that matters
The Optoma ZK521ST-B is brighter (5,000 lumens against 4,000). The BenQ AK700ST throws a given image from closer (ratio 0.69 against 0.79). The Optoma ZK521ST-B costs $200 less at the prices we observed.
Side by side
| Specification | BenQ AK700ST | Optoma ZK521ST-B |
|---|---|---|
| Brightness | 4,000 lm | 5,000 lm |
| Resolution | 4K UHD (3840 × 2160) | 4K UHD (3840 × 2160) |
| Native aspect | 16:9 | 16:9 |
| Throw ratio | 0.69–0.83:1 | 0.79:1 |
| Distance for a 10.5 × 8 ft 4:3 screen | 9′ 8″ | 11′ 1″ |
| Brightness on that screen | 36 fL | 45 fL |
| Light source | Laser | Laser |
| Rated life | 20,000 h | 30,000 h |
| Zoom | 1.2× | Fixed |
| Lens shift | — | Vertical 104–125% |
| Input lag | 16 ms (1080p game mode); 33 ms at 4K | 16.7 ms (4K 60 Hz); 8.6 ms (1080p 120 Hz) |
| Price seen | $2,899 | $2,699 |
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 ZK521ST-B
Choose the Optoma ZK521ST-B if your room has ambient light or a large screen or price leads the decision.
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