What is ghosting on a monitor?
Ghosting is the faint trail you see behind a moving object on screen. It happens when pixels can't change colour fast enough to keep up with the refresh rate — the previous frame's colour is still partially visible when the next frame arrives. A 144 Hz monitor refreshes every 6.9 ms, so any pixel transition slower than that smears into the next frame. Ghosting is worst on VA panels (which can have 8–15 ms grey-to-grey response), better on IPS (3–5 ms), and almost absent on OLED (0.1 ms) or fast TN (1 ms).
How does the pursuit camera test work?
When you smoothly track a moving object with your eyes, your retina behaves like a camera mounted on a slider — the moving object becomes stationary on your retina and the background becomes streaked. Any imperfection in the moving object itself is then revealed: slow pixel transitions appear as trails, and overdriven transitions appear as inverse-coloured halos. The original methodology comes from Mark Rejhon at Blur Busters. Track with your eyes only — keep your head still — and use the highest speed your eyes can comfortably follow.
What is overshoot / inverse ghosting?
Manufacturers add 'overdrive' (sometimes called Response Time Compensation, RTC, or AMA on BenQ panels) which briefly drives pixels past their target voltage to make them switch faster. Too much overdrive and pixels overshoot the target — leaving a pale or inverse-coloured halo in front of the moving object. If you see a clean trail behind: overdrive is too low. A bright halo in front: overdrive is too high. Most monitors have 2–4 overdrive presets in the OSD — pick the one with the cleanest pursuit at your typical refresh rate.
What is a good response time number?
Manufacturer-quoted '1 ms GtG' figures are typically the fastest single transition with maximum overdrive — often producing visible overshoot. Real-world average response (TFT Central or RTINGS measurements) is more honest. For matching a 60 Hz refresh you need <16 ms; for 144 Hz, <7 ms; for 240 Hz, <4 ms. OLED panels respond in 0.1 ms, effectively eliminating ghosting at any refresh. If your pursuit looks clean here, your response time matches your refresh rate well.
Why does the moving square look blurry even on a fast monitor?
Two reasons. First, sample-and-hold blur: every LCD and OLED holds each frame for the full refresh interval, and your tracking eyes blur the static image. The only fixes are higher refresh rates or backlight strobing (ULMB, ELMB, DyAc, BFI). Second, your eye tracking may be imperfect — practice keeps the object on your retinal fovea. If trails are asymmetric (long behind, short in front), that's panel response. If it's a uniform smear, that's hold-type blur. Check raw Hz with /monitor/refresh.
What's the difference between ghosting, motion blur, and judder?
Ghosting is the panel's pixel response problem — a trail caused by slow colour transitions. Motion blur is the sample-and-hold problem — your eye smearing a static frame during pursuit; this happens even on instant-response OLED. Judder is a frame-rate mismatch — 24 fps film on a 60 Hz display creates uneven 3:2 pulldown stutter. Different causes, different fixes. This test isolates ghosting. For refresh-rate matching see /monitor/refresh; for static panel quality see /monitor/uniformity and /monitor/banding.