Neodymium Filter

[pjphilli (Peter)]

Hi

I have read reviews where it is claimed that a neodymium filter will filter out
Moon skyglow. I thought that the spectrum of Moonlight was similar to white
light and so similar to star light? So how does it filter out Moon skyglow without also attenuating the whole light spectrum including star light and nebulosity?
Has anyone had actual experience with this type of filter?

Cheers Peter

[peter_4059 (Peter)]

I have the Baader one - good at improving contrast in planetry viewing - doub't it filters out moon skyglow though.

[pjphilli (Peter)]

Hi Peter
Yes it is a strange claim but widely spruiked as a selling point for this filter.
Hopefully someone can provide an explanation.
Cheers Peter

[MikeyB (Michael)]

Originally Posted by pjphilli

..widely spruiked as a selling point for this filter

I also have one and agree with Peter's assessment, although I find the contrast improvement pretty modest. I can't recall reduced "moon skyglow" as a selling point - where exactly is this claim being made?

[pjphilli (Peter)]

Hi Mikey

The following is an example where it is stated that

"Neodymium glass which filters out a few specific wavelengths from streetlights as well as skyglow from the Moon."

See full review at:

http://www.alpineastro.com/filters/filters.htm

Other sites selling this filter make similar claims.

Cheers Peter

[Screwdriverone (Chris)]

I have a neodymium "Moon and Skyglow" filter which I used to use a fair bit when I was doing visual from my light polluted Sydney Suburban back yard. In fact, it was ALWAYS on my favourite eyepiece when out the back.

It does reduce the moon wash somewhat, although not to the point where its all gone, but it does enhance your enjoyment when that damn Luna is up and blazing.

It's worth a shot if you have some serious LP where you are (in Nova Scotia, apparently......as your distance to me in Sydney is 5,508km.... )

However, it isnt a cure all, simply a couple of panadol.

Cheers

Chris

[pjphilli (Peter)]

Hi Chris

I have never worked out what that "distance" means. No I am not in Nova
Scotia but I am sure the imaging conditions would be much better than at Thornleigh in Sydney near Pennant Hills road and its highway sodium lamps. So Kellyville Ridge seems good by comparison.

However, I notice that the Neodymium filter has a nice big dip in the sodium light range. I have an IDAS light pollution filter which is good in this respect but it rather severely cuts back all the spectrum as well. I understand from reports that the Neodymium filter works very well in comparison and does not have such a severe cut back on the rest of the spectrum.

As for reduction in Moon skyglow I had visions of being able to image during bright Moon periods as I am getting a bit desperate with yet another dark Moon period slipping away with little imaging opportunities!

However, your comment on some reduction of Moon skyglow may tempt me to get one of these filters as the price seems reasonable.

Thanks for your advice.

Cheers Peter