The difference that matters
The Optoma ZK521ST-B throws a given image from closer (ratio 0.79 against 1.09). The Optoma ZK521ST-B lists higher resolution (4K UHD). The Optoma ZK521ST-B costs $490 less at the prices we observed.
Side by side
| Specification | Optoma ZK521ST-B | Panasonic PT-VMZ51S |
|---|---|---|
| Brightness | 5,000 lm | 5,200 lm |
| Resolution | 4K UHD (3840 × 2160) | WUXGA (1920 × 1200) |
| Native aspect | 16:9 | 16:10 |
| Throw ratio | 0.79:1 | 1.09–1.77:1 |
| Distance for a 10.5 × 8 ft 4:3 screen | 11′ 1″ | 13′ 9″ |
| Brightness on that screen | 45 fL | 52 fL |
| Light source | Laser | Laser |
| Rated life | 30,000 h | 20,000 h |
| Zoom | Fixed | 1.6× optical |
| Lens shift | Vertical 104–125% | Horizontal and vertical |
| Input lag | 16.7 ms (4K 60 Hz); 8.6 ms (1080p 120 Hz) | — |
| Price seen | $2,699 | $3,189 |
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 you need to mount it close to the screen or image detail matters most.
Panasonic PT-VMZ51S
Choose the Panasonic PT-VMZ51S if you prefer its maker, seller or ecosystem — the published figures do not favour it.
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