Use a four-check sequence to distinguish aspect-ratio mismatch, optical focus, scaling and screen alignment.
Identify which image is wrong
Look at the projector menu first, then the computer desktop, then the simulator. A sharp projector menu with a soft desktop suggests an input or scaling issue. A sharp desktop with a soft simulator points toward the application’s render resolution or graphics settings. If everything is soft, begin with focus and physical alignment.
Check 1: focus and screen plane
Display fine text or a test grid. Focus using the control provided by the model after allowing the projector to settle as instructed in its manual. If one side is sharp and the other is not, inspect whether the lens is square to the screen and whether the screen surface is flat. Heavy digital correction cannot make two different physical screen distances identical.
Do not pull an impact screen excessively tight to improve the picture. Screen tension also affects how the ball rebounds. Handle projection geometry and safe screen mounting as related but separate tasks.
Check 2: shape, not just size
Compare the white viewing area’s width-to-height ratio with the displayed content. A 16:9 picture fitted inside a 4:3 surface will leave unused space unless the system deliberately crops, stretches or renders a different aspect ratio. Each choice has a cost: cropping hides content; stretching changes proportions; a supported custom output may reduce usable pixels.
Use the existing aspect-ratio guide for the size comparison. For troubleshooting, decide first whether keeping the whole undistorted image is more important than filling every edge.
Check 3: computer and application settings
Choose a projector-supported resolution in the operating system. Then check which display the simulator uses and its full-screen/render settings. Mirroring a control monitor and projector can force a common resolution that is unsuitable for one of them. If the hardware and application support it, an extended desktop lets each display use its own mode.
Check 4: edge correction
After physical alignment and optical controls, use the projector’s available geometry tools sparingly. Features vary by model; an automatic screen-fit function on one BenQ is not proof that another model has it. Save or photograph the working settings before experimenting.
When to stop adjusting
Stop if good focus is impossible across an otherwise flat screen at a documented lens distance, or if the image has persistent lines, color blocks or an indicator error. Record photos of the internal menu and a known source image. Those two photos help separate an optical problem from a source problem.
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