Measuring your Working distance
1-Adjust your chair height so that your knee angle is 90-110 degrees, with feet flat on the floor.
2-Relax your shoulders and sit with your back straight.
3-With elbows tucked in to your body, bring your hands to a 90 degree angle.
4-Tilt your head to look at your thumbs together.
5-In this exact position, Measure the distance between your eyes and your thumbs.
6-Repeat a few time until you get a consistent number within 2-3mm