Hi All,

Second post of the evening, I'm afraid; a frustrating time at the moment, with a couple of problems!

I have enjoyed pretty much trouble-free autofocus with FocusMax and RoboFocus on my LX200. Occasionally, when using AcquireStar to focus, the RoboFocus driver seems to lose its' place; the position counter seems to be dropped, and a large, random focus movement results. If I don't notice and intervene manually, autofocus fails.

Here's an extract from a FocusMax log showing a typical case:

21:36:14 ** Beginning Focus run **
21:36:14 LS: -0.226672 RS: 0.226798 PID: 1.40 NFHFD: 10
21:36:14 Move direction: Out
21:36:15 Filter = Unfiltered (slot 4)
21:36:15 Current position = 7817
21:36:15 Focus Start HFD: 20
21:36:15 Min/Max flux setting = 100/300K
21:36:15 Find star binning = 2x2
21:36:15 Inital exposure = 1
21:36:23 Could not calibrate image - check MaxIm Set Calibration window
21:36:24 Focus binning = 1x1
21:36:27 Decreasing exposure Time
21:36:27 Total Flux = 1726467, next exposure = 0.12 sec
21:36:30 Target star found at X = 342, Y = 220 Flux = 219405
21:36:30 Focus exposure will be 0.12 sec
21:36:30 Position , HFD , Mean Best Focus , X , Y , Flux
21:36:30 7817 , 3.61 , 0 , 342 , 220 , 219405
21:36:39 7745 , 9.10 , 0 , 338 , 217 , 205545
21:36:39 On correct side of focus
21:36:39 Moving to start HFD
21:36:47 7697 , 10.62 , 0 , 336 , 225 , 72338
21:36:54 Star is too close to frame edge or is too weak; increasing frame size
21:36:54 Increasing frame width
21:36:57 7656 , 27.60 , 0 , 337 , 217 , 195176
21:37:12 7690 , 22.79 , 0 , 341 , 218 , 188544
21:37:12 Move to Near Focus HFD
21:37:25 7718 , 17.24 , 0 , 340 , 217 , 186947
21:37:38 7 , 10.30 , 0 , 341 , 217 , 195425
21:37:38 ** Starting Near Focus **
21:37:38 Position , HFD , Mean Best Focus , X , Y , Flux
21:37:38 7 , 10.30 , 52 , 341 , 217 , 195425
21:37:40 7 , 10.50 , 52 , 342 , 218 , 179135
21:37:44 7 , 11.62 , 54 , 343 , 218 , 186053
21:37:47 7 , 11.05 , 54 , 342 , 218 , 189830
21:37:50 7 , 11.02 , 54 , 341 , 218 , 201381
21:37:50 Best Focus is: 54
21:40:58 Star is too close to frame edge or is too weak
21:40:58 Increasing frame width
21:41:02 No star found

You can see that, at 21:37:38 the focus position 'jumps' from 7718 to 7; this is not a commanded move, but results in a problem on the next focus move (in this case, when FocusMax commands RoboFocus to move to the best focus position of 54 units).

This problem doesn't occur often - maybe once every five nights or so - but can obviously ruin a night's observing. I'd be grateful for any pointers as to where to start troubleshooting.

Thanks in advance,

Simon.