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At high power, it tends to come and go with the seeing, so even slight seeing changes might lead one to see an apparent change in visibility that was not actually due to some optical combination's effect.

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Hi Dave, the combo ep/bar was exchanged several times with ep alone and the visibility followed the ep/bar every time, 'seeing' was the first thing thought of and the reason we changed back and forth a few times. It was really visible and then not visible when the optics were changed using the same magnification, though we did not view other things to judge an overall improvement not just with planetaries. I don’t recall the magnification used exactly but it was relatively moderate from my recollection of the view. This view was a few years back.

If no one has any more suggestions as to what optically may have been happening, besides poor quality high power ep, then empirical testing may show something. I appreciate those with barlows taking a look.

It’s too bad we don’t have a ray-trace guy to confirm that nothing happens in the manipulation of the light cone. I believe the guys’ scope was an f4.5 with no coma corrector. Why do I keep thinking the coma’s gotta get reduced, tighter star images, as it goes to f9 cone with a barlow? I don’t have a problem being wrong, do it all the time actually, but I’d like to see why. At that point I learn something.

Steven

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Mr. Wizard
Elements in Harmony I, an 8"f6 German Equatorial - Stellafane Winner,
II a 20"f4.2 Newt-Dob - Astrofest Winner,
III a 6"f3.5 Finder/Newt-Dob, and
IV a 36"f4.5 Newt-Dob - "If it's up there, it's in here."
www.DarkSkyObserving.com

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