Re: Odd behavior of temperature-compensated focuser


Dave Schwartz
 

On 2020-09-16 12:06 p.m., Howard Dutton wrote:
On Wed, Sep 16, 2020 at 08:17 AM, Dave Schwartz wrote:

I disagree. If I've gone to all the work of achieving perfect
focus without TC on, I would not be prepared for the simple act of
enabling TC to muck it up massively and have to do it again.

I'd say turn TCF on and leave it that way.  But if you want to be able to both turn on and turn off TCF without the focuser moving, the indicated position has to change.
That would be one way. Don't do any focus before turning it on, just put up with the massive movement and then focus with it on (possible now that the bug that caused the movement to one end or the other is fixed). However, I still don't get it... the temperature didn't change between the instant when it was off until it was on so why such a massive movement?

I suppose you would like the no movement or change in indicated position at all when turning on TCF; and add the extra steps +/- into the current position when turning it OFF?
When it is turned off, I wouldn't expect any change from the position it is currently at (a temperature-compensated distance from where it was when you turned it on) either.

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