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Old 08-08-2013, 09:59 PM
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naskies (Dave)
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Originally Posted by LewisM View Post
Concerned now that I won't be parfocal with this set, as they all seem to tighten up in different positions etc.
Isn't parfocality associated with the relative thicknesses of the filters? Provided that the filters are orthogonal to the axis of light, a few mm either way shouldn't make a difference (if I remember my first year optics lectures correctly).

Originally Posted by LewisM View Post
Mike, your blasted curse hit here today - the Westerlies struck, and not even worth considering imaging, even though the sky is perfect. GRRRRRR
Wind? What wind? I love guiding with adaptive optics...
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