Calculating distance with an Axis Camera 206

[Citrus]

My team is using an axis camera to calculate the distance to a target. The distances we are currently calculating are up to a foot off, depending on the location, lighting etc. The calculated distances are worse at angles. What accuracy range are other teams getting? Do you think the camera is the best way to get the distance? We have also done tests with the ultrasonic sensor which is sometimes very accurate and other times gives strange results.

Thank you.