Tips

1.Slippage can occur in a focuser which may result in the final focus position drifting when running back to back focus runs or when running consecutive Vcurves. Go through the focuser mechanism and inspect / tighten pinion gears in a rack and pinion focuser, tighten rollers that interface with the draw tube in Crayford style, etc.

2.Backlash:

Verify that Backlash is turned on in either FocusMax or the focuser driver but not both. The backlash setting will verify and is highly dependent on the focuser and telescope construction. For example, the traditional SCT that focuses by moving the primary mirror will require significant backlash in the winter as the mirror may experience slip-stick due to the grease applied in the ways.

Most users set the focuser backlash in the direction against gravity so as to lift the payload if appropriate for your telescope. This is difficult for a Newtonian on a German Equatorial that will experience various focuser orientation depending on where the telescope is pointed in the sky.

What backlash setting to use? This will depend on the focuser  - it is best if you can measure it directly with a drop indicator or reference the manual or ask the manufacturer.

3.Verify that you focuser will move through the entire range of motion from 0 to max travel and that is able to move this distance in one contiguous move. If not, then open the driver window and make adjustments. Before testing, verify that the Limit End of Travel Position setting in Menu/Open/Options is set to 0.

4.You are setting up a new computer and need to transfer your system.ini files:

a)Open FocusMax on the original computer

b)Select the System Tab

c)Pres the small button to the right of the system name at the bottom of the window to identify the path where the files are stored (default C:\Users\XXX\Documents)

d)Open FocusMax on the new computer and create or modify the default path

e)Copy all of the .ini files to your new computer

5.If the Vcurve appears flat at the bottom then increase the max HFD setting to extend the height of the Vcurve if possible.

If the Vcurve has a flat top then it may indicate that the focuser has reached end-of-travel and slippage is occurring.

6.If a focus run fails and the focuser returns to the last known good focus position then check if the Return to start position is enabled. If the HFD from the focus run  exceeds this setting, then FocusMax will consider the focus run a failure and return to the previously known good position. It is also a good idea to setup FocusMax yo take 3 - 5 at the conclusion of the autofocus run images which will be averaged before determining if the final HFD is unreasonable - see Menu/Open/Options/Final Focus Images ( Final Focus Images ).

7.The parameters in the Vcurve window will automatically update when the cursor leaves the text box.

To turn this feature off, open the active system.ini and find the entry: AutoUpdateVcurveParameters and set to 0 (default = 1 enabled).

8.To achieve a better Vcurve calculation set the Images/position = 3 to average momentary seeing effects.

Next watch the FocusMax Log while running a Vcurve and note the 'lowest' HFD value recorded and its associated 'Position' value. (Some people run Vcurves to find their best focus position instead of performing a FocusMax Focus cycle. I've tried this, it does pretty good, but takes longer compared to a normal Focus run.)

When the Vcurve cycle completes adjust your 'Center' value to the best HFD's Position from the Log and run another Vcurve, the 'V' should be centered more precisely.

If you found each Vcurve to consistently increment, I'd look closely at your focuser.

a) First check your Backlash settings.

Backlash should 'only' be set in "one" place.

FocusMax 'or' in your Focuser's Driver not both. This tip has always been important to FocusMax.

b) Check your focuser is not slipping.

After several Focus runs or Vcurves can your focuser be commanded to return to Zero successfully?

If it returns to Zero on the counter is there any gap of the drawtube before being completely closed?

If there is a gap that could indicate slippage, where the counter is incremented but the drawtube not being moved, slippage.

c) Here's a 'poor' test for Focuser Slippage:

Change the direction the focuser movement, from In to Out or visa versa.

If there is slippage in 'both' directions then the Position increment will appear in both directions. The reason this is a poor test is it is not reliable because the weight load, camera, field corrector/reducer, filterwheel etc., being moved will react differently dependent upon whether the load is being 'lifted' against gravity or 'lowered' with gravity. You may find your system performs better if you 'lower' your load than the recommended lifting of the load.

"May You Go Among The Imperishable Stars"

Joe Mize  www.cav-sfo.com

Chiefland Astronomy Village (CAV), Fla

StarFields Observatory, (SFO).

8.How to move a window back on to the screen when it is off the screen and not visible.

a)Alt-Tab to the desired window

b)Press Alt-Space to open the Control Menu

c)Press the M key for Move

d)Press the left or right arrow key, depending on where you think the window is.

9.Using FocusMax with a Relative focuser:

FocusMax works great with Relative Focuser's. The only disadvantage is that the operator has to manage the position of the focuser since FocusMax can not tell when it hits the end of travel. Here is a procedure for manually taking V Curves for a Meade MicroFocuser and an LX-200 but it should also work well with your JMI and LazyFocus.

a)Manually move the focuser all the way in to the stop. Then time it while it moves all the way out to the other stop. This will give you the total travel time which is about 20 seconds for my microfocuser. Take this time in seconds and multiply it by 1000. This will give you the number of counts for the full range of your focuser. For my microfocuser this is 20,000.

b)Set the microfocuser to be approximately half way between the two stops. Manually focus the LX-200 using the primary mirror focuser knob. This will properly center the V Curve for your focuser range.

c)Manually move the Focuser all the way IN.

d)Launch FocusMax and make sure that the red number in the Position box near upper left side of window is "0". If it is not zero then double click on the red number and it will go to zero.

e)Click on the Setup Tab and look in the upper right to make sure that Move Out is selected.

f)Click on the FocusMax V Curve button to open the Vcurve Sequence window.

g)Click on the End Points radio button.

h)Enter "0" in the Initial box.

i)Enter the number of counts determined in step 1 into the Final box.

j)Take the number of counts determined in step 1 and divide it by 30. Put this number in the Step Incr. box. For example if you have 20,000 counts in step 1 then the number for the Step Incr. box would be 666. FocusMax should automatically give you a value of 30 in the Steps box

k)Click the Run button and it should take the V Curve over the entire range of your focuser.

10.Some tips to get FocusMax working with my nSTEP controller from Rigel Systems:

a)Make sure your account has ADMIN privileges.

b)Start your ASCOM compliant stepper controller software and check if it can run the stepper directly

c)Right click FocusMax shortcut and check properties/compatibility tab and and make sure the "run

d)in compatibility ..." and "run with admin..."check boxes are NOT checked.

e)Start FocusMax and pick the system tab, select your focuser application and connect.

f)Select the focuser tab. Correct focus position and temperature should be displayed.

g)Click on "jog" at the top and see if focuser moves.

11.Tutorial on setting up the MoonLite focuser.

12.Tutorial from Rigel Systems

13.How to install the FeatherTouch (NOT MicroTouch!) ASCOM driver on Platform 6 and WinXP through Win7 - click here