What size should the targets be?
Can I use different size targets on the same measurement?

The target size depends on the distance from the camera to the object. A rough rule of thumb is to use a target 2 millimeter (0.040") in diameter for every meter of object size. For example, you should use a 6 mm diameter target for a 3 meter object. If necessary, you can use smaller target sizes by increasing the strobe power. For best results, we recommend you try to use the same size targets on a measurement whenever possible. However, target sizes which vary by up to 2 to 1 in size are usually acceptable. See Target Sizes for more information.