For 5SE: Lumicon UHC, Orion Ultrablock, or DGM NPB
Posted 29 September 2013 - 02:39 AM
Posted 29 September 2013 - 04:16 AM
A very warm welcome to CN and to this particular forum ! :bow:
If you want to know anything about filter application, our CN colleague, David Knisely is, without a doubt, the man to seek out.
Here for example is one of his treatise on the subject. I would strongly recommend reading what he has to say on the topic before you purchase.
Remember that there is no one, all purpose filter; each being specific in varying degrees, for the task it's designed to undertake.
I naively bought a Lumicon UHC some years ago looking for an "all singing, all dancing" filter to reduce my local light pollution, but I was soon aware, after using it, of its limitations. For example, it brings out the finer filaments of the diffuse Orion Nebula very well but turns them green and certainly diminishes the brightness of the background stars quite severely.
Again, it serves well to enhance emission nebulae but does nothing of any great significance for galaxies or star clusters. "Horses for Courses" as I think the expression goes !
Bearing in mind then, that many of these more specific filters are relatively expensive, I'd advise you to accumulate as much information about that/those which will suit you and your surroundings best, before you buy.
Hoping this helps,
Posted 29 September 2013 - 08:53 AM
- Dan McShane likes this
Posted 29 September 2013 - 09:31 AM
The filters you mention are sometimes referred to as Nebula filters. That's because they filter out nearly all light except that in a narrow band which is produced by emission nebulae. The result is that it darkens the background for these objects, making them much more visible and bringing out more detail. These kinds of filters tend to have a very noticeable effect - when viewing emission nebulae. For all other objects, the filter will just make them darker.
On the other hand, light pollution filters let all the light through except a few notches where light pollution tends to be. In theory, these filters should work on ALL targets to some degree. While these sound like they would so a great job, in fact their effect is usually slight to non-existant. The problem is that light pollution comes from so many different sources, with so many different wavelengths, that much of it is not affected by the filter's notches.
Now, you may actually be in somewhat of a unique situation. If lights in your area show that orange glow, they are probably high pressure sodium. These are the ones that the light pollution filters tend to specifically target. So it's possible that you may see more of an effect from a light pollution filter than most people.
The question is - how widely are these lights used in your area? While the lights on your street can certainly cause problems with glare and direct lighting of the sky above you, light pollution comes from all around you as far away as 50 to 100 miles. If you're near a good sized city, your local lighting is only part of the LP issue. And the broader LP probably comes from lots of sources like mercury vapor, car lights, low pressure sodium, LED lighting etc. However, if you're in a smaller town and they tend to use the same kind of lighting on most of the streets, an LP filter might help some.
Bottom line - you may benefit from an LP filter (Astronomik CLS is a good one) but like others, you may find that they provide little to no benefit. A nebula filter will definitely improve your views, but only on emission nebulae. I have the Orion Ultrablock and it works well for me.
Posted 29 September 2013 - 10:24 AM
Posted 30 September 2013 - 03:22 AM
Posted 01 October 2013 - 01:57 PM