one filter

[apaulo]

this might have been asked before but ive never seen it sorry if i missed it. i have yet never used a filter and am thinking of trying 1 for general observing dso, messier, etc, basically if its up there id like to try and see it. my question is , if you could only use 1 filter 2 at the most what would you use.  thanks for any interest and replies. paul.

[clarkpm4242]

Hi @apaulo

I recommend a UHC filter as a first option.  Great help in seeing numerous DSOs and has a more natural eyepiece view than e.g. an OIII filter.

There are numerous suppliers.

Hope you get to use it!

Paul

[John]

A UHC is usually the one recommended as a single filter option. If you can make it a good one, eg: Astronomik or Tele Vue Bandmate II then they can be really effective on nebulae. I've found the lower cost ones have somewhat less impact in all honesty. These filters can improved the contrast of nebulae. They have no real impact on star clusters or galaxies.

For a few years I just used an O-III filter instead of a UHC (that was an Astronomik) and found that I did not miss the UHC much. I have both now though. O-III's have more impact but on a slightly smaller range of targets.

 

[Zermelo]

Some links you might find useful:

https://www.prairieastronomyclub.org/useful-filters-for-viewing-deep-sky-objects/

https://www.prairieastronomyclub.org/filter-performance-comparisons-for-some-common-nebulae/

https://stargazerslounge.com/topic/369823-uhc-and-oiii-filters/

https://www.eyepiecesetc.com/Choosing_a_Nebula_Filter_p/nebula-filters-explained.htm (click on "extended information" tab)

[Ricochet]

3 hours ago, apaulo said:

1 for general observing dso, messier, etc,

There is no such thing as a filter for general observing. A CLS might have been an option ten years ago but with the move to LED lighting they are less effective. Your choice of filter depends on the type of object you are observing. As a quick summary I would say:

• Moon and planets: Neodymium, the Baader one if you can afford it.
• Star clusters (open and globular): More magnification, so long as you keep the exit pupil at 1mm or higher, and the cluster fits in your field of view.
• Galaxies: Sometimes a CLS seems to help a little, but really you need to get to darker skies.
• Emission Nebulae: UHC and OIII filters. From a dark site UHC performs better on a larger number of objects, but with increasing light pollution the tighter filtering of an OIII becomes more valuable. Filters are the one item where going for a top end product 9e.g. Astronomik) really pays off IMO. 

[RT65CB-SWL]

There is no general observing filter that does all. That said...

• my most used single filter is the Baader Neodymium...
  https://www.firstlightoptics.com/light-pollution-reduction/baader-neodymium-filter.html
  for general observing. I often call it or refer to it as my 'Swiss-army knife' filter.
• I also use the Explore Scientific UHC and OIII...
  https://www.firstlightoptics.com/explore-scientific-filters/explore-scientific-uhc-nebula-filter-1-25-2-inch.html
  https://www.firstlightoptics.com/explore-scientific-filters/explore-scientific-o-iii-nebula-filter-1-25-2-inch.html