Full Moon Lunar Contrast Filters

Discussion for all the moon watchers.

Full Moon Lunar Contrast Filters

Postby Nightspore » Mon Oct 24, 2016 11:58 pm

After some experimentation, predominantly on 102mm and 130mm scopes, I have narrowed down my filter selection to three Wratten filters. When the Moon is in any other phase than the Full Moon period/phase I tend to just use a Baader Neodymium or no filter at all. Where I live I can get 200x to 300x on the Moon fairly easily for around an 0.5mm exit pupil. Lunar detail is best perceived at around 150x or above in my opinion. Filter use is very subjective and these are my opinions only of course.

Above: ND 0.6, #21 & 82A TS Optics (Guan Sheng Optical) filters with M28.5x0.6 filter threads

There are times however that during a bright near 100% phase lunar detail is difficult to see through the glare and whiteout effect of the Full Moon. It could be argued that there is usually some terminator detail even on a Full Moon, even if it's slight. So, after much fiddling about in the dark under a Full Moon, a red torch and loads of filters, I've decided that these three offer the best contrast and can allow some details, such as rimae, dorsum, ghost craters inter alia to be viewed which would otherwise be washed out somewhat by the glare. Of course, your mileage may vary.

1/ Neutral Density ND96 0.6 (25% transmission)

This doesn't introduce artificial colour and masks much of the glare/whiteout.

2/ #21 Orange, longpass filter blocking visible wavelengths below 530 nm, (46% transmission)

I find this far better as a contrast filter than yellow or yellow-green filters. Good for daylight/twilight viewing as it turns the blue sky black. Does tend to make the Moon look like a Terry's Chocolate Orange.

3/ #82A Light Blue (73% transmission)

With 43% more transmission than the #80A Blue filter this is far more suitable to apertures of 130mm and under in my opinion. It very subtly, and I think, more capably reveals surface features compared to the #80A.

I replaced my original Celestron filters with the TS Optics/GSO filters as the M28.5x0.6 filter threads pretty much fit everything. The older filters were from a variety of sources and didn't always thread onto all of my eyepieces or diagonals universally.

I hope this has been useful.

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