Lunar filter advice...

Can anyone recommend a cheap 'n' cheerful lunar filter? Having picked up a Skylux I'm finding that the moon is blinding me (huge difference from the 60mm Aldiscope - and that came with a crappy filter!). Any advice on a somewhat decent yet inexpensive filter for a 70mm refractor (the eyepieces are threaded BTW). Thanks!

Can anyone recommend a cheap 'n' cheerful lunar filter? Having picked up a Skylux I'm finding that the moon is blinding me (huge difference from the 60mm Aldiscope - and that came with a crappy filter!). Any advice on a somewhat decent yet inexpensive filter for a 70mm refractor (the eyepieces are threaded BTW). Thanks!

A very experienced lunar observer told me not to use a moon filter but instead use high magnification and illuminate the observing area with white light. That reduces glare sufficiently to obviate any need for a filter.

As you've discovered, some moon filters are of poor quality and some turn the moon green. If you do want to use a filter, best get a neutral density or polarising filter which do not introduce false colour.

Although I haven't used it, Baader's Neodymium Moon & Skyglow filter gets good reviews, e.g.:
www.cloudynights.com/item.php?item_id=114&pr=2x9x42

Gordon

Thanks Gordon! I like the idea of using high magnification and an illuminated observation area - more natural viewing than through a filter. I suppose locating the telescope beside a lit window would work. Any other suggestions folks?

You could try reducing the aperture of the scope. You can do this by using a piece of cardboard and cutting a circular hole that is smaller then the native aperture of your scope and place this over the front of the scope. You may want to experiment with the size of this hole.

You could try reducing the aperture of the scope. You can do this by using a piece of cardboard and cutting a circular hole that is smaller then the native aperture of your scope and place this over the front of the scope. You may want to experiment with the size of this hole.

Some observers do use an aperture mask but that is with large aperture scopes where they reduce aperture to perhaps 4 inches to reduce brightness and glare. I shouldn't think it's a feasible proposition for a 70 mm refractor. Also, while an aperture mask may reduce glare, it also reduces the resolution of the telescope to the diameter of the hole in the mask. Like deep sky, aperture wins out even when viewing a bright object like the Moon as the greater the aperture, the more detail can be resolved on the lunar surface.

For example, the resolving power of a 70mm scope is 1.7" so _theoretically_ 3.4 km diameter objects should be visible on the lunar surface. Reduce aperture with a mask to 50 mm and resolving power reduces to 2.4" and 4.8 km objects. A larger 150 mm telescope has a resolving power of 0.8" with 1.6 km diameter objects _theoretically_ visible.

Gordon

Thanks John! But I reckon Gordon is probably right when considering that I have a 70mm scope. Anyone else use a lunar filter or alternative method?