Planewave Instruments: Auto-Focus with ACP & PWI3

[Brad Vietje]

MANY thanks to Bob Denny and the good folks at Planewave for putting their heads together to allow ACP to use Planewave's PWI-3 software to make auto-focus runs. We've had lots of problems with FocusMax, but the PWI Auto-Focus routine is superb. I like everything about the PWI-3 platform.

Here's a screen shot that shows tonight's first focus run... A very interesting feature is that the entire field is divided into a 3x3 array, and a separate V-curve and focal position is calculated for each segment, so you can see if there is any residual miss-alignment of the image train. The yellow highlighted area shows that our system currently does have a slight tilt from upper left to lower right. This probably results from our last filter swap-out back in April. There is a fair amount of play in the "secure fit" connections between filter wheel, auto-guider, and focuser, so if these components are not held perfectly flush against their mating surfaces, a little tilt can be introduced -- or even a little lateral translation is the set screws are not tightened evenly. The optional graph shows the focus positions, and to the left are the 9 segments, and a separate V-curve can be displayed for each.

The PWI software is very easy to use, and very user-friendly; thanks for making it an option for use with ACP!

Clear skies,

Brad Vietje
Newbury, VT
Northern Skies Observatory/ Northeast Kingdom Astronomy Foundation web site: www.nkaf.org