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Moon Too Bright In Scope?

Discussion in 'Beginner's Corner' started by Astro_Padawan, Oct 2, 2015.

Moon Too Bright In Scope?

Started by Astro_Padawan on Oct 2, 2015 at 1:14 PM

30 Replies 6436 Views 1 Likes

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  1. Astro_Padawan

    Astro_Padawan Member

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    Maybe I just need to get used to it and learn to adapt but the Moon was extremely bright through a friend's refractor. Do I need to suck it up and learn to adapt or are there filters meant for this? Was it because he had a very low end scope? Maybe other conditions because of the eclipse?

    We had used the scope 3 nights in a row. The 3rd night being the night of the recent total lunar eclipse. I would just like observe for longer periods of time through the eyepiece and not have to look away because it gets blinding :(. Maybe I'm just staring too long? :p
     
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  2. Crow Haven

    Crow Haven Well-Known Member

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    The moon is really quite bright, you might try a polarizing filter or neutral density moon filter to help your eyes. Most of the time I don't use one...but sometimes it's helpful and easier on the eye. It's not as bad in the smaller aperture scopes.
    Enjoy the moon!
     
  3. clintwhitman

    clintwhitman Well-Known Member

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    Hey Bud,
    Clint here this issue will depend on two things, how much aperture. How much magnification, Smaller scopes will not be as bright, like a 60mm refractor. If you are using larges aperture like 4" and above the brightness will be intense unless your trying for high power which will diminish the brightness. I cant even look at the moon with the Pearl without a filter, it will burn your eye. I have been using a solar wedge it cuts the intensity of the light way down. If you are using 1.25 eyepieces I would take Crow havens advise and get a polarizing filter. You can turn them to increase or reduce the amount of light they let pass and they screw right into most eyepieces. they come in both sizes
    http://agenaastro.com/bst-1-25-variable-transmission-polarizing-filter.html

    (aveman
     
  4. AstroLife

    AstroLife Active Member

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    Hello,

    Crow Haven and Caveman are correct in the posts above. You do need some sort of a filter to cut back on the brightness, even in a small telescope using low magnification. Your options are:
    • Basic Moon filters (but these impart a green color to the Moon that I am not a fan of)
    • ND or Neutral Density filters (that offer a fixed amount of light reduction; downside is that you might need more than one depending on the phase of the Moon or the magnification employed)
    • Single Polarizing filters (that provide a small variation in the amount of light that passes through), or
    • Double or Variable Polarizing filters (that provide the greatest control and variation in the brightness).
    The good thing is that all of these are reasonably cheap and they all do a good job. My personal favorite is the variable polarizing filter since this will pretty much cover you in any and all situations with small telescopes.

    One other "poor man's" option you can also consider is making cardboard masks with a central cutout of varying sizes that is smaller than the telescope's aperture. Just stick it in front of the telescope and you have effectively reduced the aperture of the telescope and hence the Moon's brightness.

    I believe our sponsor carries all of the above types of filters here.

    All the best,
    Harry D.
     
  5. BillP

    BillP Well-Known Member

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    FWIW, if the eyepiece you are using has long eye relief so it can be used with eyeglasses, then absolutely no reason in the world why it would be detrimental to the view if you just wore your sunglasses when you observe a bright Moon. Give it a try.
     
  6. Crow Haven

    Crow Haven Well-Known Member

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    What a great idea -- sunglasses!:D
     
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  7. Astro_Padawan

    Astro_Padawan Member

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    Ha! I didn't even think to use a pair of sunglasses. I'll likely get the appropriate filter, but using sunglasses sounds effective. Just need to be sure to remove them after viewing. I bet I'd trip on something in the low light and regret it really quick.

    Thank you for the details @Crow Haven, @clintwhitman and @AstroLife!
     
  8. Robert Clark

    Robert Clark Well-Known Member

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    Well I walked into this one late. My advice.... Everything they said above. When I first started out, which has been only a few years now, I went the cheap route first because I had it right there in the house. Was sitting at the scope (xt8) and thought "man, I wish it was a bit dimmer." Jumped online with my phone, read a little, then went to the garage for a cardboard box and duct tape! Bam! Instant aperture mask! Like was stated though, at really high mag it dims it down some. I have a moon filter now, but sometimes it is used, sometimes not. Even though its pretty bright, I like the "natural" look.
     
  9. Dr. Ski

    Dr. Ski Well-Known Member

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    I am always lauding the #82A blue filter and #11 yellow-green filter to newbies and this is another wonderful application. In my 102mm refractor, I just use either one of these on the moon. They dim the light intensity slightly and enhance details along the terminator, which is the area you should be focusing on (pardon the pun). Those $12 GSO filters are great and should be in every observer's arsenal. The #11 filter has the added advantage of mitigating chromatic aberrations (purple "hazing").
     
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  10. pogobbler

    pogobbler Member

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    It always does seem very bright, but, technically speaking, the surface brightness of the moon through a scope can never be greater than the surface brightness of the moon, naked eye. The scope gathers more light, of course, but spreads it over a larger area, too. I've used filters before to tone it down, but I've come to prefer the view filter-less.
     
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  11. Mak the Night

    Mak the Night Well-Known Member

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    I find the Wratten #8 Light Yellow filter works quite well. Blue 80A and 82A are good for revealing hidden detail on a bright near Full Moon. I find neodymium filters and neutral density filters all work well.

    [​IMG]
     
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  12. aeajr

    aeajr Well-Known Member

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    I have 2 "moon" neutral density filters, one 25% and one not marked but I guestimate it at 40%. Both work well on the moon but I favor the 25%.

    Mak the Night,

    I have not tried any of my colored filters on the moon but I may give them a try based on your suggestion.
     
  13. Mak the Night

    Mak the Night Well-Known Member

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    Well, overall conditions can dictate filter use generally, but I find the Wratten light yellow and light blue filters can work quite well at revealing detail without the colour of the filter itself looking too unnatural. A Wratten #21 Orange (46% transmission) is also very good, especially in twilight conditions.
     
  14. tripod tipper

    tripod tipper Well-Known Member

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    I too have 25% and 40% filters for moon observing. Many years ago when I first started, we did use sun glasses, we didn't know of a moon filter at that time. I did recently use sunglasses until I received the filters. Since then the moon hasn't ben in the sky, maybe I cursed it?
     
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  15. klaatu2u

    klaatu2u Member

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    I wear my 'shades' with my long eye relief eyepieces... I do have filters but my various sunglasses seem to work very well.
     
  16. tripod tipper

    tripod tipper Well-Known Member

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    I do like the sunglasses!!:D
     
  17. Dan Acker

    Dan Acker Member

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    I don't know about sunglasses or blue filters but I use a 13% transmission Moon filter. Doesn't matter what size telescope or eyepiece. Thread that baby into your eyepiece and enjoy. Increases contrast and saves the eyes.
     
  18. tripod tipper

    tripod tipper Well-Known Member

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    Thanks Dan,

    Tonight will be a full moon and clear skies. I'm going to screw in my 40% and try that one out for the first time, thanks for reminding me. I would rather spare the retina.

    Dennis
     
  19. Dave In Vermont

    Dave In Vermont Well-Known Member

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    Sunglasses is good, as well as 13% Moon-Filters (and blue, Baader Neodymium, and I'll stop now!) and anything else that works.

    The sunglasses reminds me of an episode of the old black & white TV-series: The Addams Family. The episode where the family is lying about in their yard - in sunglasses - at night. They were working on their Moon-tans in their bathing-trunks. And warning each other not to get a Moon-burn.... :D

    I'll go hide now -

    Dave
     
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  20. Nebula

    Nebula Well-Known Member

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    Hello! I usually spend much of my time watching the moon at around 200x, (around 0.8 exit pupil) plus a Neodymium filter on my eyepiece and some ambient light too. (2 led torch) with that I am ok to watch the moon and sketch a little bit. It's easier for the eyes.

    If i want to look at the moon at low power, I use the Orion variable polarizing filter which is a great filter. I also use it at 200x sometimes. Mandatory for me.

    Woups this is my first post, hello everyone! I am new from Canada! I enjoy astronomy very much like you!
     

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