position accuracy

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position accuracy

Post by nemecl » Sun Aug 08, 2010 9:28 pm

I just ordered the FCUSB controller for my JMI focuser. It will probably work. I have one question: will the reproducibility of the position (based on the elapsed time) will be adequate for adjusting the focus during a night when the temperature varies (at this time of year) between som 13 C to 2 C. My Celestron C11 aluminum tube (carbon fiber tubes were not available years ago when I bought it) shifts the focus noticeably.

An approximate reproducibility of the position (total time elapsed) may be more than adequate. I plan to focus the scope manually early in the evening with the time elapsed counter reset to zero. Experimentally I will determine the correlation between the focus adjusted (the first night) about twice or three times and the time needed to do so.

Subsequently, monitoring the temperature (I have a temperature probe close to the scope), I should be able to adjust the focus. Unfortunately, I can no longer communicate with my Canon Rebel XSi camera - its USB interface broke down for the third time and I am not going to waste my time with another repair that will not last too long. My previous Rebel XT also lost communication after the warranty period. Canon obviously has not clue how to make these circuits reliable. What else is new?

Has nothing to do with Shoestring, of course. Do you thin this has a chance to work? If you think the chance is very low, I may have to cancel my order.


Ladislav Nemec, Big Bear, CA

The PayPal payment of $80 was made yesterday.

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