Best filter for CCD imaging moon?

[Leedsgreen]

Dear All,

I currently use a modded SPC900NC (fitted with ICX098BL b&w chip) to image the moon through my Skymax 127. At the moment I just use an IR/UV filter but have been thinking about getting another filter to improve image contrast etc.

Could anyone tell me if this is actually possible and if a filter will improve an image?

If so, what would be a good filter? I've heard good things about the Baarder Neodymium filter and am also wondering about a colour filter but unsure how to chose between, say, #29 deep red or #21 orange filter?

Any advice would be gratefully received,

Thanks,

Nick

[Psychobilly]

I like using IR pass but they can be expensive... so I would try deep red...

[beamish]

I'd 2nd that ! wratten 25 should be fine tho, i have heard of someone on the forum who uses a blue filter- not too common that and as I've never tried it I can't recommend it.

[brianb]

Depends on the quality of the seeing and the aperture ... the worse the seeing, the longer the cutoff frequency; the bigger the aperture, the longer the cutoff frequency. For people with reasonable seeing and moderate apertures, either the Wratten #29 or the Planet Pro 732 will usually be somewhere close to optimal.

Try a green filter (Wratten #58) if the seeing is abnormally steady, especially with an achromatic refractor.

[riklaunim]

Pro Planet expensive? It's one of cheapest filters And it helps a lot when imaging moon.

More advanced is to make false color of IR-Green-UV but UV filters are expensive.

[Leedsgreen]

Thanks as ever guys,

Reckon I'll give the #29 a go and see what effect it has. Plan to pick up this weekend (will that give enough time for clouds to clear for Feb's moon nights)?!

Nick

[Psychobilly]

Pro Planet expensive? It's one of cheapest filters And it helps a lot when imaging moon.

.

When compared to a coloured glass filter it's expensive....

Billy...

[brianb]

When compared to a coloured glass filter it's expensive....

Depending on the quality of the glass, of course.

Another issue here is that dye-in-glass filters were almost all designed to work with photographic film, which has no response in the near infra-red, consequently there is no IR blocking in the filter; this does not matter for red (long pass) filters but it does for the others, e.g. the Wratten #47 "violet" actually transmits more strongly in the near IR than it does in visible violet! If you don't use an IR blocking filter as well, when using a dye-in-glass colour filter for CCD imaging, the results may well not be what you expect. Those "expensive" dichroic (interference) filters don't have this issue.