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Micro Touch focuser accuracy test - Video footage

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#1 bilgebay

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Posted 20 January 2013 - 04:35 PM

Following my adaptation of Starizona's Micro Touch focus control system to my FSQ106EDXIII ( please see this thread ), I wanted to test the precision of the total system.

Here is a 10 minute video, where you can see MT moving the FSQ focuser 40 times with great accuracy. The resolution of my dial gauge is 10 microns unfortunately but you can still estimate the in between values.

http://www.youtube.c...h?v=5udtUml8XGY

and here is the second test run, this time for 5 minutes:

http://www.youtube.c...h?v=uF3GBQD4FA4

Here is the Sequence Generator Pro's main operation window as I customized it to my taste.

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and this is the filter setup screen to demonstrate the different focus positions I made up for each filter. I will have to find the real values under the sky as soon as I have a clear night available for shooting.

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All in all, I must say I am very happy with the systems performance in general. I have heard from several friends that Micro Touch was not landing the focuser at the same point precisely, that mostly it was overshooting. I am thinking that this could be caused by a backlash in their system.

SGP allows the user to take care of the backlash issue. In the video you will notice at times the focuser goes outward than proceeds to the determined focus point. This takes care of the backlash. If the next point is further inward then this maneuver is not needed, focuser is directly moved to the focus point determined, without pulling the draw tube 25 counts back ( IIRC this was the value I put into the system considering my focuser has 9 counts backlash)

Your comments and questions are welcome as always.

#2 Nils_Lars

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Posted 20 January 2013 - 05:17 PM

Looks like you solved the issues here , nice work Sedat.

#3 bilgebay

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Posted 22 January 2013 - 07:03 AM

Thank you Erik. Now all I need is a few clear nights to see the system in real life situation. I am confident it will work without any glitches though.

Clear skies to you.

Sedat

#4 frozen.kryo

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Posted 27 January 2013 - 02:57 AM

Hi Sedat,

I don't know if you've read this: Feathertouch Focuser Adjustment by Mike Dodd.

I came across this while browsing DC3 Dreams' site. His testing methodology of using a dial gauge is similar to yours. He does have very interesting results.

I'd imagine repeatability would be better for the motorized crayford style focuser compared to my motorized SCT microfocuser, as shown in your video.

For my SCT microfocuser, I get focus drift of up to 75 steps per night manually focusing.

I haven't done any autofocusing so far as the weather has been *BLEEP* and I don't have maxim nor ccdsoft to use with focusmax. I'll probably buy SGPro in the near future to try out it's autofocus routine and backlash compensation.

To be clear though, the drift might have more to do with my OTA (backlash, thermal related stuff, mirror shift/flop etc.) than the focuser itself.

#5 bilgebay

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Posted 27 January 2013 - 03:18 AM

Www! Great paper. Thanks for sharing. It will definitely help me in fine tuning my setup.

I haven't done any testing on my SCT microfocuser yet regarding the backlash and repeatability. However, I've done the base work some time ago. You can read it here.

Clear skies

Sedat

#6 frozen.kryo

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Posted 27 January 2013 - 03:26 AM

Hey no problem. Glad to help. :)

#7 bilgebay

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Posted 27 January 2013 - 03:36 AM

I have edited my reply. Please have a look at it.

#8 bilgebay

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Posted 27 January 2013 - 03:42 AM

I forgot the control software subject. I guess SGP is the way to go. They have just released version 2.1 with lots of goodies. Additionally, there is a free lite version available, that is you download the regular version and after the trial period expires it falls back to the Lite functionality. I think this is great value.

#9 frozen.kryo

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Posted 27 January 2013 - 04:02 AM

Thank you for linking that other thread. Excellent thread with lots of useful info. I'll give it a thorough read.






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