Thank you for your reply. I aim to achieve measurement accuracy within ±0.05 mm. Do you think thats possible? Furthermore regarding the accuracy I would guess that it’s crucial to consider lens distortions.
Incorporating a reference object of known length alongside the object of interest would be possible and provides a means to measure a second object of non known length.
Nevertheless regarding calibration: Do I even need the focal length in order to measure the size of an object, with a reference, as you described it? Do I need any of the calibration results at all? (Maybe except lens distortion.)
Tank you in advance for your support and time
Best regards
Marius