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  1. #1
    Join Date
    Jun 2007
    Perth, Western Australia

    Default FMx + Optec TCF - strange temperature reported at end of focus run

    We're experiencing an intermittent temperature controlled autofocus idiosyncrasy where the final reported temperature is -274.0

    11:42:38 19:42:38 ** Beginning Focus Run **
    11:42:40 19:42:40 ...Current position: 3758
    11:42:40 19:42:40 ...Current temperature: 13.9
    11:46:38 19:46:38 Focus position = 3761 Avg HFD = 2.44 Avg FWHM = 1.72
    11:46:38 19:46:38 Temperature: -274.0 Filter: Clear (slot 1)
    11:46:38 19:46:38 ** AutoFocus Completed **

    The initial reported temperature is correct, but by the time we're at the end of a 2-4 minute focus run (using FMx via ACPS) something has gone amiss. I thought the problem might be hardware related, eg a faulty temperature probe or use of 50 foot TCF control cable, but at this stage I've only seen the problem occur during a focus run.

    We're using FMx's Acquire Star feature, running periodically from ACPS. Latest versions of all software.

    Has anyone seen this and have any clues?


  2. #2
    Join Date
    Nov 2005
    Virgil, NY


    Hi Paul,

    I had a similar issue with temperature reported from my focuser (a TCF-S). I don't remember the value reported, but when the ambient temperature sensor attached to the focuser went bad, it reported a screwy number that was clearly not the real temperature. I bought a new probe from Optec, but it turned out that it was only the connection to the focuser that had become loose enough to cause the problem. You might check that connection.

    Coincidentally I think, -274 is a few tenths of a degree C below absolute zero.
    Pier-mounted Meade 12-inch SCT "classic"
    w. focal reducer to f/5.3 ~ FL 1630mm
    Optec TCF-S focuser
    SBIG CFW-8A and ST7-XME
    FOV ~ 15' x 10'
    H-alpha, BVRI, RGB & Clear filters
    MaxIm and, of course, ACP!
    AAVSO Code: BRIC



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