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CJK
professor emeritus


Reged: 12/05/12

Loc: Northeast TN
moon filter new
      #5567889 - 12/12/12 04:10 PM

I've read through many of the threads here having to do with filters, and I must say I am not sure I'm any clearer than before I read them. I think I'm going to stay away from them altogether for now, with one exception:

Since we'll be doing a fair amount of moon viewing with our new baby (if nothing else, I'm pretty sure we'll be able to locate that our first night out!), can someone recommend a good moon filter? It looks like we'll have both 1.25" and 2" EPs, so I suppose we'll need one of each size.

Thanks,
-- Chris


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jerwin
scholastic sledgehammer
*****

Reged: 05/17/12

Loc: Romeoville IL
Re: moon filter new [Re: CJK]
      #5567959 - 12/12/12 05:05 PM

I have a Zhummell polarizing moon filter I picked up from telescopes.com in both sizes. It's nice because you can adjust the brightness. kind of hard to adjust being that the filter is inside the focuser, but once you get it dialed in it's pretty nice.

A while back I bought a little $10 one and it wasn't great. it was plastic so it never wanted to thread on properly and gave the moon more of a green tint.

Whatever brand you go with is probably here nor there on a moon filter, I'd mainly suggest the polarizing ones.

Jim


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jerwin
scholastic sledgehammer
*****

Reged: 05/17/12

Loc: Romeoville IL
Re: moon filter new [Re: jerwin]
      #5567962 - 12/12/12 05:06 PM

and some people use sunglasses so they don't need to keep changing the filters around. I've never done this myself but I'm sure it would work as well as a single filter, the polarizing ones still give you that adjustment that is very nice.

Jim


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CJK
professor emeritus


Reged: 12/05/12

Loc: Northeast TN
Re: moon filter new [Re: jerwin]
      #5567992 - 12/12/12 05:31 PM

I like the sunglasses idea! Especially as the kids will surely get a kick out of wearing their sunglasses at night!

I was able to find a 1.25" variable polarizing filter, but I'm having a harder time with the 2" size.

-- Chris


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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: moon filter new [Re: CJK]
      #5568001 - 12/12/12 05:38 PM

Quote:

I've read through many of the threads here having to do with filters, and I must say I am not sure I'm any clearer than before I read them.




That's the thing about filters, if they were clear, they wouldn't work.

As far as moon filters, some use them, I have several but I don't find them useful. My eye quickly adjusts to the moon just as it does when I turn on a light.

Jon


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killdabuddha
Pooh-Bah
*****

Reged: 08/26/11

Re: moon filter new [Re: Jon Isaacs]
      #5568019 - 12/12/12 05:53 PM

We really like our 13% and use them more than not. Probly coulda gotten by with them in 1.25" format as we do most lunar viewin there. Oh well. Guess the $$ seemed negligible as compared with the Ultrablocks.

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JohnMurphyRN
sage
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Reged: 09/09/12

Loc: Near St Louis
Re: moon filter new [Re: killdabuddha]
      #5568051 - 12/12/12 06:21 PM

The moon takes high mag fairly well, and high mag dims things down a bit. You can also leave the porch light on while viewing the moon.

I don't see a need for a moon filter and view the moon(even near full) at 100-411x with 17.5" of aperture sending photons into my eyes...ymmv


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beatlejuice
Pooh-Bah
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Reged: 04/05/11

Loc: Hamilton, ON,Canada
Re: moon filter new [Re: CJK]
      #5568058 - 12/12/12 06:30 PM

Quote:

It looks like we'll have both 1.25" and 2" EPs, so I suppose we'll need one of each size.




Whatever filter or filters that you eventually get you might as well buy them in the 2" size as they can usually be screwed into the telescope end of your diagonal enabling you to use them with either 1.25 or 2 inch eyepieces.

Eric


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Tony Flanders
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Reged: 05/18/06

Loc: Cambridge, MA, USA
Re: moon filter new [Re: CJK]
      #5568205 - 12/12/12 08:05 PM

Quote:

Since we'll be doing a fair amount of moon viewing with our new baby (if nothing else, I'm pretty sure we'll be able to locate that our first night out!), can someone recommend a good moon filter? It looks like we'll have both 1.25" and 2" EPs, so I suppose we'll need one of each size.




I'm not a fan of Moon filters at all, but I really can't imagine why anybody would ever use a 2-inch Moon filter.

The whole point of 2-inch eyepieces is to achieve wide field and low power. And there's no point in viewing the Moon at low power; it gains you nothing at all.

The same statement applies, even more so, to filters for viewing planets. Only deep-sky filters make sense in the 2-inch format.


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CJK
professor emeritus


Reged: 12/05/12

Loc: Northeast TN
Re: moon filter new [Re: Tony Flanders]
      #5568275 - 12/12/12 09:02 PM

That's really an excellent point; I hadn't thought of things that way.

Well, at least it seems there's ONE thing I can cross off the shopping list!

-- Chris


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Seldom
professor emeritus


Reged: 08/05/12

Loc: N of Cedar City Light Dome
Re: moon filter new [Re: Tony Flanders]
      #5568282 - 12/12/12 09:08 PM

Quote:


I'm not a fan of Moon filters at all, but I really can't imagine why anybody would ever use a 2-inch Moon filter.

The whole point of 2-inch eyepieces is to achieve wide field and low power. And there's no point in viewing the Moon at low power; it gains you nothing at all.

The same statement applies, even more so, to filters for viewing planets. Only deep-sky filters make sense in the 2-inch format.




But if you have a 2" coma corrector on a Newt, it's sort of handy to be able to put any filter on the bottom end of the coma corrector. Then you can swap eyepieces without swapping filters. A 1 1/4" filter on an EP can bottom out on the lens of a 2" coma corrector.


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beatlejuice
Pooh-Bah
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Reged: 04/05/11

Loc: Hamilton, ON,Canada
Re: moon filter new [Re: Tony Flanders]
      #5568399 - 12/12/12 10:30 PM

Quote:

I'm not a fan of Moon filters at all, but I really can't imagine why anybody would ever use a 2-inch Moon filter.





It would not be for using with 2" eyepieces, but for experimenting with different powers without having to change the filter over for every eyepiece that you use. Since this type of filter is relatively inexpensive, it might be a convenient option for someone who does want to use a moon filter. I won't get into color filters, but the same could also be said of them.
For nebula filters you definitely want 2" if you have a 2" focuser on a refractor.
It is because the OP is using a 2" diagonal with a refractor that this all makes sense to me.

Eric


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jerwin
scholastic sledgehammer
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Reged: 05/17/12

Loc: Romeoville IL
Re: moon filter new [Re: Jon Isaacs]
      #5568471 - 12/12/12 11:34 PM

Quote:


As far as moon filters, some use them, I have several but I don't find them useful. My eye quickly adjusts to the moon just as it does when I turn on a light.




I have no idea how some of you veterans do it. I look at the moon time to time without a filter and when I stand up or look away from the scope I'm completely blind in that eye for a few minutes.
Jim


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FlorinAndrei
scholastic sledgehammer


Reged: 09/28/10

Loc: California
Re: moon filter new [Re: CJK]
      #5568532 - 12/13/12 12:38 AM

Don't buy any Moon filter before you try to work out the peculiarities of observing this object.

Observe the Moon at high magnification. If magnification is at least half the maximum magnification of your scope (i.e. when exit pupil is 1mm or less), the Moon is dimmed tremendously. This happens no matter what aperture you're using.

Secondly, the stereotype of the astronomer observing in deep darkness is just a stereotype. The Moon benefits a lot from having some ambient light around you. For the Moon, I install the scope right across the street from the street light in front of the house. Never used a Moon filter.

There's this tendency in the beginning to buy more stuff, but it becomes more beneficial when it morphs into learning more stuff.


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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: moon filter new [Re: jerwin]
      #5568686 - 12/13/12 05:32 AM

Quote:

Quote:


As far as moon filters, some use them, I have several but I don't find them useful. My eye quickly adjusts to the moon just as it does when I turn on a light.




I have no idea how some of you veterans do it. I look at the moon time to time without a filter and when I stand up or look away from the scope I'm completely blind in that eye for a few minutes.
Jim




Jim:

You are not blind in that eye, rather your eye has adjusted to the brightness of moon and it will quickly readjust. It's no different than walking outside from a lit room except that only one eye is affected.

Dark adaptation is a big plus when viewing faint objects but when viewing brighter objects, it can be a detriment, your rods are not sensitive to color nor do they provide the resolution of the cones. As Florin points out, viewing the moon and planets can benefit from ambient light. This keeps your eye from dark adapting. As astronomers we become so used to protecting our dark adaptation that we don't realize that there are situations when dark adaptation is a disadvantage.

A couple more observations:

- The moon is just not that bright, not that intense. Look at the moon against the blue sky during the day, it is visible but it is not bright.

- The concept that a telescope cannot increase the "surface brightness" of an extended object is difficult to grasp but nonetheless it is an important one to understand. Viewed though a telescope, the surface of the moon can never be brighter than it is naked eye.

- While a telescope cannot make the surface of the moon brighter, increasing the magnification dims the moon, even in a large telescope, at the magnifications appropriate for viewing the moon, I find myself wishing it were brighter.

- I do enjoy the moon at low magnifications (45x in a 2 inch Widefield) where it is relatively small, but bright and crisp. It can really look like a big, round rock, just hanging there in the sky.

As I said, I have several filters but do not find them useful, I merely let my eye adapt to moon's brightness and use appropriate magnifications. Think about it, consider it, maybe even try it...

Jon


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CJK
professor emeritus


Reged: 12/05/12

Loc: Northeast TN
Re: moon filter new [Re: Jon Isaacs]
      #5568726 - 12/13/12 06:49 AM

Two things I really love about these forums (fora?):

(1) People are so knowledgable and helpful
(2) I learn something new every single time I log on

Thanks, everyone!!!

-- Chris


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Carol L

*****

Reged: 07/05/04

Loc: Tomahawk, WI 45N//89W
Re: moon filter new [Re: CJK]
      #5569572 - 12/13/12 04:53 PM

Chris, be aware that the variable Moon filter might affect lunar details - the Zhumell i have certainly does - not sure about other brands.

After using a regular Orion Moon filter for over a decade, i'd read high praises for the variable filters and decided to get one. Immediately, i noticed that it didn't have the sharpness of my trusty ole' Orion filter. I might have got a lemon though, and admittedly another brand might be much better. Just thought i'd give a heads-up.

All of that being said though, you can have mine if you'd like it.
PM me your address and it'll be on its way - Merry Christmas!

EDIT:
Forgot to say - it's a 1.25" filter.

Edited by Carol L (12/13/12 04:55 PM)


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killdabuddha
Pooh-Bah
*****

Reged: 08/26/11

Re: moon filter new [Re: Carol L]
      #5569676 - 12/13/12 06:02 PM

That is SO cool

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CJK
professor emeritus


Reged: 12/05/12

Loc: Northeast TN
Re: moon filter new [Re: killdabuddha]
      #5569711 - 12/13/12 06:22 PM

PM sent. I'm kind of overwhelmed by the generosity of folks around here.

-- Chris


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Carol L

*****

Reged: 07/05/04

Loc: Tomahawk, WI 45N//89W
Re: moon filter [Re: CJK]
      #5570051 - 12/13/12 10:11 PM

Not to take anything away from the folks here at CN, but generosity has been a common trait in all of the online astronomy groups i've been in for over a decade - basic human nature.

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