If you look at the values, both show a clear trend for decreasing values.
My suspicion would be that there is slip somewhere in your focuser train: Either it is a Crayford-type that works just by friction between the axis and the tube, or you have connected the focus motor to the fine drive knob that usually also has some intrinsic slip.
But if your focuser has slip, backlash correction is quite futile anyhow. 
Read More...
© 2003-2022 by INDI Library. All rights reserved.