TEMPERATURE COMPENSATION OF FOCUS

Discussions of using SharpCap for Planetary Imaging
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windytops
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Joined: Fri Aug 14, 2020 9:49 am

TEMPERATURE COMPENSATION OF FOCUS

#1

Post by windytops »

I have a couple of elementary questions, which I ask simply for the avoidance of doubt.
I have obtained a Moonlite CS focuser for my Meade LX200 SCT. This focuser has a temperature sensor which attaches to the OTA. SharpCap/ASCOM requires that I input a temperature coefficient, that is, the number of focuser steps per degree Centigrade increments. My tests show that, at a constant wavelength, the in-focus setting follows a straight line law of [[–M* OTA temperature} +Constant.]
My first question is; do I input the negative sign to the temperature coefficient M, or does SharpCap/ASCOM already assume that it will be negative?
My next question is; having concluded a manual focus using one of the tools in SharpCap is it only necessary to then check the T Comp box to have SharpCap attempt to make continuous Temperature compensation?
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Re: TEMPERATURE COMPENSATION OF FOCUS

#2

Post by admin »

Hi,

your second question is the easy one... Once you have achieved a good focus, turning on and leaving on the temperature compensation function by ticking the box should be all you need.

Now as to the other part - positive or negative? You would need to check with the documentation of the ASCOM driver for your focuser to find that out - all of the calibration and management of the temperature compensation is handled by the ASCOM driver, not by SharpCap, so the details of how it work vary from ASCOM driver to ASCOM driver. The only thing SharpCap does from the temperature compensation point of view is send the ASCOM driver a message to turn it on/off in response to the checkbox being ticked/unticked!

cheers,

Robin
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