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Newbie Moon Filter Question

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#1 JLS701

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Posted 17 May 2022 - 01:53 PM

Hey Folks,

Glad to find this forum.

I just received my Orion 15x70 Binoculars and Tripod, and had some great Moon viewing last night.

Any ideas of how or where to get a Moon Filter, I'm not having any luck looking online, or maybe just missed it.

...or is there a successful workaround ?

 

Any help would be appreciated.

Best Regards

John S



#2 MickTaurus

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Posted 17 May 2022 - 02:11 PM

Hey Folks,

Glad to find this forum.

I just received my Orion 15x70 Binoculars and Tripod, and had some great Moon viewing last night.

Any ideas of how or where to get a Moon Filter, I'm not having any luck looking online, or maybe just missed it.

...or is there a successful workaround ?

 

Any help would be appreciated.

Best Regards

John S

Hi John, just point you to this thread:

https://www.cloudyni...s#entry11730751

 

Where Darren Henning (Royal Astronomical Society of Canada) kindly let me share a way of to adapt any current binoculars to filter use. 

 

 

Filters for Moon Darren recommended to me these:

https://www.baader-p...ow)-filter.html

 

Also good on Planets.

 

Have fun.

 

Mick


Edited by MickTaurus, 17 May 2022 - 02:15 PM.

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#3 JLS701

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Posted 17 May 2022 - 03:13 PM

Thank you Mick,

 

I'll check it out.

 

Cheers

John S



#4 sevenofnine

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Posted 17 May 2022 - 10:23 PM

Welcome to C/N! flowerred.gif

 

The answer to your simple question is complicated confused1.gif 

 

Any achromatic optic like your binocular will show lots of false color (CA/chromatic aberration) on bright objects like the Moon. The best way to control this is with the optic/binocular itself. One that is apochromatic (Apo) adds ED (extra low dispersion) glass will control some of it. Fully multi coating all glass to air surfaces helps too. That's what expensive binoculars do for the most part is control or eliminate CA. Putting a large and expensive filter on the front of your binocular will help some. Less so on the ocular side. Remember, that is two of the large ones on the front  moneyeyes.gif That's what MickTaurus is getting at. Basically, the cost is prohibitive. So, the real answer is you have to live with it or get an optic that by design has no CA. That would be an expensive Apo binocular or a mirrored telescope like a Maksutov (Mak for short). A very good relatively inexpensive Mak is a Celestron C-90. That would be my recommendation. Best of luck to you and your choices! jump.gif


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#5 Astronoob76

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Posted 18 May 2022 - 01:26 AM

You don't really need an expensive Apo to not see color on the moon. My vintage 20x60 Tento shows no color fringing on the moon. Most of the porros don't (or it's minimal). Roof prisms might be more of a problem concerning CA. But even cheaper ones can be had with ED glass like the Svbony SV202.
I had some lovely views of the moon even with my low mag 7x30 Komz. But that one has a rather sophisticated ocular with lots of different coatings which might have helped with the CA.
I noticed that all the vintage Russian binos are particularly good at suppressing chromatic abberation but they have a yellow tint to the image because of the glass used.
I'll have to do a little comparison with some other optics especially on the moon to see which is best.

Edited by Astronoob76, 18 May 2022 - 01:30 AM.

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#6 JLS701

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Posted 18 May 2022 - 08:25 AM

Hey Guys,

 

Thanks so much for the detailed info, much appreciated.

 

JS



#7 sevenofnine

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Posted 18 May 2022 - 11:48 AM

The topic of CA with achromats has been discussed with some heat flame.gif on this forum. It's there if you know where to look for it and some folks are more sensitive to it than others. Some of it has to do with our vision and how each person sees color. We are not all the same. How an optic is made has a lot to do with the degree of CA too. Very inexpensive binoculars made today will show quite a bit of it. My Oberwerk LW series is a porro design that shows some but is somewhat corrected with all air to glass surfaces being fully multi-coated. Even so, I rarely use these for Lunar observation. But if I do, I've learned to ignore the light show grin.gif



#8 Alan French

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Posted 18 May 2022 - 12:05 PM

When people think of achromats and talk about secondary color, they are talking about the on-axis variation of focus with wavelength. Achromats are generally designed to bring blue (F line) and red (C line) to the same focus. The green will focus closest to the lens and when our eye, which is most sensitive in green, says the view is focused, the blue and red ends of the spectrum will be out of focus. This, however, is rarely visible at low powers and large exit pupils, it requires relatively high magnifications to make it visible to the eye.

 

What people usually notice is lateral color from the eyepiece. It's a variation of magnification with wavelength. If you move the bright Moon to the edge of the field, almost going out of the field, you'll see fringing from the color magnified the most. If you bright the bright edge of the Moon just into the field, you'll see the color magnified the least. With the high contrast between the dark sky and the Moon's limb, few eyepiece's are free of lateral color, although it is limited by the narrow apparent view of many binocular eyepieces. 

 

Clear skies, Alan



#9 Rich V.

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Posted 18 May 2022 - 02:37 PM

Is John, the OP, just asking about neutral density filters to lower the brightness of the Moon?  He didn't say he was trying to eliminate chromatic aberration.  confused1.gif

 

Rich


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#10 Alan French

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Posted 18 May 2022 - 03:28 PM

In answer to "Do I need a Moon filter?" my answer is an emphatic "No, you don't." 

 

Compared to other celestial sights it certainly seems bright, but with time your eyes will get used to the brightness and it will seem just fine. My first serious telescope was an 8-inch Newtonian and the idea of a filter never came to mind, they didn't even appear to be much on an amateur astronomer's radar back then. After these questions starting appearing on the internet I was curious and bought a "Moon" filter and a pair of polarizers, where the brightness can be adjusted.

 

The Moon has dark, black shadows and surprisingly brilliant whites. Both filters turned the blacks a bit grayish and subdued the bright whites. The filters have sat, unused, for decades. 

 

I use 15x50 IS binoculars and sometimes turn them toward the Moon. I've never felt the need for a filter. 

 

Clear skies, Alan



#11 JLS701

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Posted 18 May 2022 - 07:00 PM

Hey Guys,

You guys are batting well above my average  : )

I'm just getting into it, so I'm playing catch up here.

 

Can't believe the other night I actually saw differences in height of the topography of the moon at the edges of the Moon itself. WOW.

Blue eyes here, so I think I just have a sensitivity to light, always have.  Can't go out on a sunny day without sunglasses.

 

I think checking in on the Moon when it first comes up is going to work best for me, it's still a muted color, and not that bright.

 

Thanks Guys

Cheers

JS



#12 MickTaurus

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Posted 19 May 2022 - 09:53 AM

I think checking in on the Moon when it first comes up is going to work best for me, it's still a muted color, and not that bright.

 

Thanks Guys

Cheers

JS

First (and last) quarter is a good time to view, shadows cast by the sun at the terminator are at their longest and pull the scenery into stunning relief.


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