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Yellow Halo Around The Edge Of The Moon


Matt2011

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Thought i'd clarify as it's clear enough tonight

In the centre and bottom of the eyepiece (I.e. Moon positioned centrally or forwards the lower portion of the viewable area) the moon tonight (focussed and slightly defocussed) appears to have a yellow highlighter drawn around its circumference, occasionally (depending on where it is wishing the eyepiece) across the terminator too.

Viewed in the top extremity of the eyepiece it has a yellow top limb and almost ultraviolet (I.e blue / purple) lower limb, terminator looks neutral / normal.

It's quite a powerful effect on occasion. Does this match what other Helios Apollo Apollo 15x70 users see?

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Yes. This is to be expected with a 70mm achromatic objective operating  at f/4 (or less). "Normal" binocualrs are not the instrument of choice for the Moon and bright planets; their strength is the larger "faint fuzzy blobs", especially open clusters.

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Thanks Steve, good to know It's not unusual or abnormal. Agree they're not the ideal things to view the moon in, and the 'scope is certainly more effective, but it's still a beautiful image to behold and, just by the back door, it takes a few seconds to set it up for the kids, can't ask for more, yellow fringing or no.

All the best and, dare I say it, being the first of December: ... Merry... no, I can't quite do it yet, give it a couple of weeks ;)

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I also get a thin yellow fringe around one side of the moon on my Quantum 6,3 100mm binoculars, but if I move my eyes around I can get rid of it, no problems with clusters and galaxies though. Steve

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I experienced some rather noticable 'Apple and Plum' colouration around the 98% full Moon when I tried out my Helios Apollos straight out of the box.My initial reaction was that I'd expected them to be better corrected for CA.Then I realised that the Moon was to all intents and purposes FULL,and it was BONFIRE NIGHT,so the sky was full of C***,and the fact that I was looking out of the bedroom window didn't help! Since trying them on the Moon again under more acceptable(and realistic!) observing conditions,I'm more than happy with their performance in this respect.

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I compared the views through my much loved Helios Apollos to my (equally loved) APM triplet APO with 31mm Nagler (at 15.5x) here:

http://stargazerslounge.com/topic/193207-tales-from-santa-luce-tuscany-episode-v-great-globular-and-wide-field-shoot-outs/

The CA correction of the APM is clearly superior, but the cost of getting that kind of optical performance into binoculars would be astronomical. As I should have noted in the report, the bins cost less than the single eyepiece used in the scope.

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