Guest Hansen Posted June 23, 2013 Share Posted June 23, 2013 I was wondering if there were any filters I should consider first off. Certainly looking at a moon filter, but not sure about light pollution filter?. Where I live, the back is very dark, but front of house is a street light about 30 meters away from where I plan to setup when the sky is clear. Also, not sure about other planetary filters or whether to avoid these for the time being or at least until I become more experienced. Link to comment Share on other sites More sharing options...
Brantuk Posted June 23, 2013 Share Posted June 23, 2013 A moon filter is a good idea for a basic filter. If you're near street lights a dew shield helps cos it also blocks light from the sides that bounce around the tube reducing contrast. Some folks use a light pollution filter but I don't know how well they work - never used one. Other filters can be used specific to the type of object you're looking at - but you won't be needing those for a while and someone will be more than happy to demo one at a meeting if you ask around. Link to comment Share on other sites More sharing options...
dawson Posted June 23, 2013 Share Posted June 23, 2013 A moon filter, or natural density filter, will be useful for lunar work. From what i hear, light pollution filters are useful if you've got lots of aperture, like 250mm or more, otherwise the very faint Deep space objects which normally look like faint fuzzy things (And generally very small) just look even fainter. Again. As i said on the other recent beginner thread, i'd have a go at using one on your scope before buying one. I suspect you'd decide not to buy one for observing. Imaging may be different. James Link to comment Share on other sites More sharing options...
xanthic Posted June 23, 2013 Share Posted June 23, 2013 As said above, if you've got a street light near by, a dew shield will help. I live a couple of miles from Nottingham city centre; the light pollution to my north is pretty bad. I bought an LP filter and too be honest it was a waste of £40. It certainly does block out the sodium glow, but the reduction in light passing through the scope does not make it a better view. It might work out if I do some EP projection work, but for visual, I would not bother. Link to comment Share on other sites More sharing options...
Guest Hansen Posted June 23, 2013 Share Posted June 23, 2013 Thanks fellas. I think I will leave them for the moment, but just get a moon filter and when I get to a meetup take it from there. Much appreciated. Link to comment Share on other sites More sharing options...
dawson Posted June 23, 2013 Share Posted June 23, 2013 I think the natural density filter 0.9 (9% light transmission i think) is meant to be good for lunar work. I've got a spare cheap moon filter you can have. Private message me your address and i'll post you it tomorrow or tuesday. Or collect it from mine (west bridgford) either monday night or sometime tuesday. Its not fancy but will give you an idea what they do. James Link to comment Share on other sites More sharing options...
dawson Posted June 23, 2013 Share Posted June 23, 2013 Thinking about it, i think it means 9% light is blocked, 89% transmitted. Jd Link to comment Share on other sites More sharing options...
dawson Posted June 23, 2013 Share Posted June 23, 2013 Balls, 91% transmission. Maths never was my good subject along with english, french, physics, chemistry, PE, religion: i was ok at cooking, biology and geography. Link to comment Share on other sites More sharing options...
Tweedledee Posted June 23, 2013 Share Posted June 23, 2013 In my experience, the best moon filter is a variable polarising filter. This screws on to the end of your eyepiece and you can simply twist the two polarisers to vary the brightness attenuation between 2% and 40%. It does not change the colour like some moon filters do. This will allow you to achieve the best possible view by changing the setting to suit the phase of the moon and the size of your scope. It is obviously far brighter when full than as a crescent. They are more expensive than other fixed density filters. Having said that, the one that James has, would also do a fine job for you, and a variable polariser could be something to upgrade to in the future. The cheapest one I have seen is £20.00 here... http://www.ebay.co.uk/itm/Antares-Variable-Polarising-Filter-1-25-Chinese-made-moon-planetary-filter-/190844350656?pt=UK_Photography_Telescopes&hash=item2c6f35b0c0 Link to comment Share on other sites More sharing options...
dawson Posted June 23, 2013 Share Posted June 23, 2013 Peter, are the natural density filters by baader just fixed percentage polarising filters, or do they also add some colour? James Link to comment Share on other sites More sharing options...
Tweedledee Posted June 23, 2013 Share Posted June 23, 2013 I think, what you are talking about are normally called *Neutral* Density filters. These do not change the colour (give the natural colour) and are of fixed attenuation. As far as I know they are not polarizing filters. They are usually of better quality than the cheap filters which often give an unnatural green hue. Link to comment Share on other sites More sharing options...
dawson Posted June 23, 2013 Share Posted June 23, 2013 Neutral, yes, you are right. Ok, thanks. James Link to comment Share on other sites More sharing options...
dawson Posted June 23, 2013 Share Posted June 23, 2013 Baader neutral density filters: http://www.firstlightoptics.com/moon-neutral-density-filters/baader-neutral-density-moon-filters.html Thanks phil. James Link to comment Share on other sites More sharing options...
Tweedledee Posted June 23, 2013 Share Posted June 23, 2013 It is often sufficient to simply stop down the aperture of the scope to allow less light in, and thus reduce the moons brightness. Many scope end caps have an off axis hole for a reflector (or central hole for a refractor), with a small cap a couple of inches across for this purpose. If using high power, the resolution of the scope will also be reduced to that of the smaller aperture, so very fine details may be missed. Link to comment Share on other sites More sharing options...
Tweedledee Posted June 23, 2013 Share Posted June 23, 2013 Baader neutral density filters: http://www.firstlightoptics.com/moon-neutral-density-filters/baader-neutral-density-moon-filters.html Thanks phil. James You are welcome Fred . Link to comment Share on other sites More sharing options...
dawson Posted June 23, 2013 Share Posted June 23, 2013 Haha my brother calls me fred. Sorry peter [embarrassed face] Jd Link to comment Share on other sites More sharing options...
Tweedledee Posted June 23, 2013 Share Posted June 23, 2013 It should be me making those mistakes, James, I'm drinking my fathers day whisky . Link to comment Share on other sites More sharing options...
dawson Posted June 23, 2013 Share Posted June 23, 2013 Well i hope it's tasty. Don't drink too much! Link to comment Share on other sites More sharing options...
Tweedledee Posted June 23, 2013 Share Posted June 23, 2013 Just about to get my second (largish) glass of Glenlivet . Link to comment Share on other sites More sharing options...
Tweedledee Posted June 23, 2013 Share Posted June 23, 2013 There are some people who consider the moon to be light pollution . I admit that I have avoided it for years, and have deliberately planned my observing sessions when the moon is not in the sky. Recently, I have ruined my night vision on several occasions, and have really enjoyed the view. I am now actually considering purchasing a 2" variable polarising filter . Link to comment Share on other sites More sharing options...
dawson Posted June 23, 2013 Share Posted June 23, 2013 Is this the whisky talking? All the confessions coming out...? Next you'll tell us you are a secret lemonade drinker! Jd Link to comment Share on other sites More sharing options...
Tweedledee Posted June 23, 2013 Share Posted June 23, 2013 I probably would not admit to it without the whisky, Fred. Link to comment Share on other sites More sharing options...
dawson Posted June 23, 2013 Share Posted June 23, 2013 Founder member of the Secret Lunar Observing Society Link to comment Share on other sites More sharing options...
Guest Hansen Posted June 24, 2013 Share Posted June 24, 2013 I think the natural density filter 0.9 (9% light transmission i think) is meant to be good for lunar work. I've got a spare cheap moon filter you can have. Private message me your address and i'll post you it tomorrow or tuesday. Or collect it from mine (west bridgford) either monday night or sometime tuesday. Its not fancy but will give you an idea what they do. James I am not sure how to PM you Daws. I don't see where to go on this, so assume I might need to make a certain amount of posts or be a registered member of the forum for a certain time before I can PM?. It is a very kind gesture by you and I feel I ought to pay something even if it's for postage to be fair with you. Link to comment Share on other sites More sharing options...
dawson Posted June 24, 2013 Share Posted June 24, 2013 Email me then First name @ surname . Me . Uk I'll have to post it tomorrow as at work now. Jd Link to comment Share on other sites More sharing options...
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