From: "Mel Bartels" 
To: 
Reply-To: "Mel Bartels" 


>>>
Even for photographic and ccd work, I think too much has been made of this
focus shift due to Plop's refocusing.
<<<

That's why the RoboFocus and other temperature compensating devices are so
popular despite their steep pricing.  Re-focusing for digital imaging is
often necessary every few minutes because of temperature changes anyhow. 
If you change objects and move to another quadrant of the sky, swinging the
scope from vertical to horizontal, you likely will go through a re-focusing
session anyhow.

Mel Bartels

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