FILTERS!!

Paul et al, sorry - looks like my knowledge of filters is poor when it comes to visual use. :oops:

However, I would have thought an OIII filter would not be considered broadband...?

Here are two articles well worth reading:

www.cloudynights.com/item.php?item_id=63

www.cloudynights.com/item.php?item_id=1520

I personally went for a UHC filter.

Hope this helps.

Cheers for all the tips lads! I've been readin around and a UHC seems to be the way to go...

As an aside, I'm very impressed with the level of friendliness, response to questions on the site, helpfulness, etc. Thanks again!

Paul et al, sorry - looks like my knowledge of filters is poor when it comes to visual use. :oops:

However, I would have thought an OIII filter would not be considered broadband...?

Yes, O3 is not broadband, but its peak is in an area that is easy for the eye to see. I remember at the WSP 3 years ago looking at the Veil nebula without it and been able to see it, although faintly.
With the filter, it was soooo much more visible. O3 is great but it is a specialist filter for a certain breed of objects.

Starry Plough

Great to hear you are enjoying your new scope.

I have recently ordered my UHC filter but alas non stop clouds since the day it arrived

With filters you have to be aware that the human eye works best when it sees a large amount of contrast. If there is little contrast then the eye has trouble seeing things even if the object itself is quite bright. What filters do is try to reduce the backround scattered light without reducing the light of the subject object by the same amount. The three types of filters (Broadband, narrowband and line) achive this with varying success.

Filteres will only work well on emmission nebula and not really well on reflection nebula or galaxies or star clusters. I understand this is because with emmission nebulas the actual gas in the nebula is being excited to a higher energy state by a central object that is extremely hot such as the white dwarf in planetary nebula, or the newtron star in a supernove remnant. This makes the gas in the nebula emit light at one specific wave length (such as OIII, H-alpha or H- Beta) and a filter such as the Narrowband UHC or other line filter filters out all other wavelengths to bring out extreme contrast.

It wont work very well on galaxies, star clusters or reflection nebula where the light is simply reflecting the light from nearby stars as there is no enhanced production of light at the specific wavelengths, the filter will just uniformly dim the nebula as welll as the sky backround. Thus contast is only slightly improved.

Brodband filters or light polution filters work by filtering out the light polution which sounds great but they also filter out a lot of the light in the actual subject object so again the additional contrast is not as good

I understand the UHC filter is the best all rounder with the other filters more specialised to various types of object.

The other thing to consider is the size of aperture. i understand that you have a 6" scope. With scopes of this size the filter may actually dim the object so much that you will have difficulty seeing it. There is a less powerful version UHC -E which you should consider getting rather then the full UHC.

Hope this helps

DB

That helps a lot David, thanks!