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Baader Kringe Filler & Moon and Sky Glow results



 
 
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Old May 29th 04, 06:15 PM
Pete Rasmussen
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Default Baader Kringe Filler & Moon and Sky Glow results

Hi Everybody,

I tried this Baader filter out last night for the first time with my
newly reacquired "used" Orion 100mm f/6 Astroview OTA. Thank you
Jamey Thompson for your graciousness in selling it back to me The
moon was all I was able to examine, Jupiter was dipped too low since
my having returned late from uptown events and in getting things ready
to observe with.

Good seeing conditions though. The little scope shows to handle 255x
without effort on the moon and there is no color fringe seen on the
limb at all with Meade 4.7mm UWA or Celestron 4mm Omni Plossl.
Somewhat due lowered (but not bad at all mind you) image brightness.
However that is not the entire cause in effect. It is a very fine
lens. What a surprise I've seen many much worse!

This scope is thankfully reminiscent to my superb Apogee 127 WideStar
I had reluctantly sold to friend Don Bledsoe. Sometime pending his
approval I would really love to share with you his excellent
commentary in reply on owning that magnificent scope!

Back to the Astroview, there was some lunar color fringing at lower
powers but less than I remembered in comparison when very briefly
owning/using this same scope before mainly on terrestrial targets.
That was obviously prior to my collimating it Great lens! Venus
here I come! I'm using a Zeiss Mark 5 binoviewer with 1.25x and 1.70x
correctors currently in the straight through mode on this excellent
instrument.

Now you are probably baited waiting to hear about the Baader filters,
no? The Fringe Killer most definitely sharpened the view of lunar
detail over that of integrated light. I should actually compare it
with a yellow filter to better understand its true worth. The slight
amount of purple fringing due the achromat lenses chromatism that was
seen prior was now gone at any powers. The light greenish
predominently yellow hue imparted by the filter was not too
distractive to my eyes and as expected became less noticeable over
short time at the eyepiece. It is not a world much worse for hurt in
off-coloredness than using a TeleVue Radian eyepiece as I recall. Not
the same tint though. I can't wait to try this filter on Jupiter and
terrestrial targets.

Now, adding in stack the Baader Moon and Sky Glow filter as is
commonly recommended on the net made for an interestingly (but not
totally unexpected) poor result. It left a narrow but strong purple
fringe on the lunar limb. And most importantly, the added system
glass made the image less sharp than with the Fringe Killer used alone
or without filters at all. Although I completely have doubt, having
the moon low in the sky may have played a small part in the adverse
fringe results using the filters stacked. Even though the apparent
color tone of the moon surface was close to natural (a little toward
the blue) this combination is not recommended at this point by this
observer. For reference I had the 1.25" filters placed at bottom of
the binoviewer.

Hoping this data is useful...

Clear skies,

Pete
 




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