Re: [MaxImDL] Request: Focuser limits


Nov 30, 2011

 


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#47874 Nov 30, 2011

Hello Doug,



I have a Crayford focuser on an Edge SCT, with a Microtouch absolute

position focuser in place. Backfocus is TIGHT -- I am already over 20

mm beyond where I should be, so I keep the inward travel very limited

(i.e. I keep it nearly fully racked in). Even when I have "preferred

direction of travel" set to outward, occasionally MaxIm will try to rack

the focuser further in than physical travel permits.



This doesn't damage the focuser, but it does cause two problems:



1) The counter keeps changing, even if it doesn't physically move. In

other words, it changes the "centered" position, and even though it

allows from 0 to 60,000 as positions, it drifts to the 60,000 end, at

which point focusing is no longer possible. I have to manually reset

the focuser to 30,000.



2) It causes some focus runs to fail because it can't get far enough on

the V-curve to get to the dip.



I can handle the latter by tweaking focal length and step length, but I

would love to see something that was just added to FocusMax -- focuser

position stops in software.



Even though the focuser can theoretically move from 0 to 60000, in

practice it can't move that far. It might be able to move from 16000 to

33000 with an average "in focus" location around 31000. Please let us

define "soft stops" such that MaxIm will not attempt to move beyond

either end of physical movement that I define as reasonably possible.



Thanks for listening.



Jeff W



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#47883 Dec 1, 2011

On 2011-11-30 11:12 PM, Jeff Woods wrote:

> Even though the focuser can theoretically move from 0 to 60000, in

> practice it can't move that far. It might be able to move from 16000 to

> 33000 with an average "in focus" location around 31000. Please let us

> define "soft stops" such that MaxIm will not attempt to move beyond

> either end of physical movement that I define as reasonably possible.



That is something the focuser manufacturer should be doing in their driver.

RoboFocus has the capability, for example, to set the maximum focuser travel.

The application should not be expected to have all kinds of fudges to fix

vendor-specific hardware problems. It's simply bad system design.



You should contact the manufacturer of your focuser and request this feature.



Doug



--



Doug George

dgeorge@...



Diffraction Limited

Makers of Cyanogen Imaging Products

www.cyanogen.com/



100 Craig Henry Dr., Suite 202

Ottawa, Ontario,

Canada, K2G 5W3



Phone: (613) 225-2732

Fax: (613) 225-9688



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