Exposure Time & Motion Blur Calculator
Compute the blur distance caused by part motion during exposure, express it in object-side pixels and derive the maximum exposure time for an allowed blur.
Calculator
Formula and applicable conditions
| Blur distance | b = v × t (v in mm/s, t in s) |
|---|---|
| Blur in pixels | n = b / p_obj |
| Maximum exposure time | t_max = n_allowed × p_obj / v |
Parameter definitions
| Part speed | Relative speed between object and camera during exposure, in mm/s. |
|---|---|
| Exposure time | Sensor exposure (shutter) time in µs. |
| Object-side pixel size | From the camera pixel pitch divided by the optical magnification. |
| Allowed blur | Maximum acceptable blur expressed in pixels. 0.5–1 pixel is a common starting point. |
Worked example
- Part speed 500 mm/s, exposure 1000 µs: blur = 0.5 mm = 500 µm.
- With an object-side pixel size of 5 µm/px the blur is 100 pixels — far too much for inspection.
- To keep blur within 1 pixel, the maximum exposure is 1 × 5 / 500 × 1000 = 10 µs, which normally requires strong strobe illumination and a global shutter camera.
Frequently asked questions
Does this guarantee a good image?
No. Exposure time is one factor. Illumination intensity, gain, sensor noise, motion direction and the optical transfer function also determine image quality.
Should I use a global shutter?
For fast-moving parts a global shutter avoids the skew of a rolling shutter. For very short exposures, pulsed or strobe illumination is usually required to keep a usable signal level.
What if the required exposure is too short for my lighting?
Increase illumination intensity, use a strobe synchronised with the exposure, reduce line speed, or reduce magnification (larger object-side pixels) if the inspection allows it.
Is blur the same in both directions?
Blur follows the direction of relative motion. If the part moves only along one axis, blur appears along that axis only. The calculation assumes motion perpendicular to the optical axis.
Request a POMEAS lens recommendation
Submit the parameters and the calculation result below. The form posts to the existing POMEAS contact interface; nothing is sent automatically and no data is shared with third parties.