Which filters do I need

[Adidaz 29]

like to know what type of filters I need for galaxy's and nebulas  and what price should I pay many thanks adidaz

[John]

Hi,

For galaxies, there is no filter than improves the view - getting under dark skies is the way to do that.

For nebulae either the UHC or O-III type will make the nebulosity stand out more. Prices start at around £39 for a Skywatcher UHC filter in the 1.25" fitting and go up rather high for the preimum brands such as Astronomik.

2" filters are needed if you are using 2" eyepieces.

The UHC type might be a good place to start as they have some effect on quite a wide range of nebulae.

[Adidaz 29]

Thanks john your all round know your stuff and I like your help to me on other topics many thanks

[Dave In Vermont]

I have a listing, with links, that should help you learn about these. As regards "How much £££'s?" - it's more about whose filters are best for the job in my opinion. For UHC-Filters, I feel that Astronomik are a bit better than the Baader offering. Others may disagree, of course. As for the OIII-Filter, I think it's pretty much a 'slam-dunk' that it's Astronomik again - but by a wider margin due to transmission-spectra for visual purposes, as well as imaging. So, if you follow these suggestions, it's just a matter of finding what dealer has the best price & service. So I'll start with an excellent paper by David Knisely. He's a well-known 'filter-nut' (I'm a not-so-well known one! ) who writes under the auspices of the Prairie Astronomy Club in the USA, and this article is likely his best one out there (my opinion):

Filter Performance Comparisons For Some Common Nebulae:

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

And to make it easier to transport and/or print - here's a Pdf:

Filter Performance Comparisons For Some Common Nebulae - by Dave Knisely.pdf

And here's a few more articles and links for a good overview of different types of filters for astronomy, and how they're used:

Useful Filters For Viewing Deep-Sky Objects:

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

ASTRONOMICAL FILTERS SPECTRAL TRANSMISSION:

http://www.astrosurf.com/buil/filters/curves.htm

Choosing a Color/Planetary Filter (The Agena Color-Chart):

http://agenaastro.com/choosing-a-color-planetary-filter.html

Specialty Filters (AgenaAstro - Such as UHC, OIII, Ha,...Etc.)

http://agenaastro.com/optical-accessories/filters/specialty-filters.html?p=1

 

You'll note that a 3rd. type of filter is mentioned, the Hydrogen-beta or just Hb. This gets use on a few objects, but not near as many as the UHC or OIII - which are a coin-toss regards: "Which one should I get first?"

If you should decide to get an Hb-Filter, - this is getting boring  - once again I'd recommend the Astronomik offering. It's best known target is the Horsehead Nebula - B33 - in Orion. But regardless of the use of n Hb, the Horsehead is known to be a very difficult target under the best 'seeing.'

Hope this helps!

Dave

 

 

[ronin]

As John says galaxies need a dark sky, they are easiest described as "white" so filters do little for them at leaast visually. For imaging it is an option to drop in a Ha filter and so capture the star forming regions.

Nebula you may need to know the nature of it - reflection or emission.

Next somewhat odd area is that it seems UHC filters are available in 2 slightly different types.

One of them will transmit the OIII and I think Hb wavelengths, others will transmit the OIII and Hb but also pass wavelengths up at Ha also. The problem is both are described as UHC but they are slightly different.

One of the UHC that passes both is sold by Alan at Skys the Limit, here is the link to the filter characteristics:

StL_UHC

As you can see it reports to pass at the OIII+Hb 460 to 525nM and also at the Ha end up at 650nM. Other UHC's will be OIII and possibly Hb only, no Ha. So it starts to get a little more complex. Personally and it is more a case indecision I suspect I would end up with one like the link shows, one for OIII and one for Ha. At least then I wou;ld be covered no matter what.

 

[estwing]

Shouldn't this be in the ep section mods?

[ronin]

2 minutes ago, estwing said:

Shouldn't this be in the ep section mods?

Possibly but I suspect that if asked in the EP section then people would end up recommending narrow band imaging filters. Sort of one of those areas where Eyepiece reads as more appropriate but for visual here might be a bit safer for relevant replies.

 

[Dave In Vermont]

You know? I've often wondered about where "Filters" should be put in conversations. Most just toss 'em in with eyepieces - because they screw into them? But putting it in Deep-Sky Obs. seems equally valid.

I solved the riddle in my files - I made a new section JUST for 'Filters.'

Dave

[MarsG76]

1 hour ago, John said:

Hi,

For galaxies, there is no filter than improves the view - getting under dark skies is the way to do that.

For nebulae either the UHC or O-III type will make the nebulosity stand out more. Prices start at around £39 for a Skywatcher UHC filter in the 1.25" fitting and go up rather high for the preimum brands such as Astronomik.

2" filters are needed if you are using 2" eyepieces.

The UHC type might be a good place to start as they have some effect on quite a wide range of nebulae.

I agree with the above statememnt, but do not go cheap on filters, Astronomik, Baader, , Lumicon and Celestron filters (same filter as badder) I would recommend since they're proven companies and have very good reviews. I myself use those brands and are more than happy with the quality, I have the Lumicon 1.25" UHC and 2" Astronomik UHC filters, both are fantastic and each one shows just as much detail as the next with a slight color differnce, The Celestron OIII filter works as expected and for imaging I use Baader HA, SII, OIII, HBeta... All come highly recommended.

I paid nearly $300 for the UHC filters so 39 pound seems low for a UHC filter, that is coming from where in the past I bought a generic chinese moon and sky glow filter, a Nebular filter and a UHC filter and they are no where near as good as The Lumicon, Astronomic or Baader equivalents.. I say dont go cheap to try and save because you will end up paying twice.

  

[Dave In Vermont]

MarsG76 - Please steer clear of Lumicon for now (maybe forever). I guess you've been out of the loop!

I'll dig you up the threads to verify what I'm saying later (you're on my To-Do List now), but a search here in the forums could give you the proverbial 'Lions'-Share' of data on this issue. Older (verified) Lumicon is great! For now - might as well buy from suggestion of a Rodeo-Clown!

'til later -

Dave

 

Rodeo-Clown

[Merlin66]

Hmmm

I would strongly recommend finding your friendly spectroscopic amateur and asking him/her to do an actual transmission spectrum of the filter.

This will quickly and accurately establish the performance of any astronomical filter.

No ambiguity, no guesses only factual information.

 

[Dave In Vermont]

21 hours ago, Merlin66 said:

Hmmm

I would strongly recommend finding your friendly spectroscopic amateur and asking him/her to do an actual transmission spectrum of the filter.

This will quickly and accurately establish the performance of any astronomical filter.

No ambiguity, no guesses only factual information.

 

It would also help to learn how to read these spectral-graphs of the results. Without getting too deeply immersed in the technical data. Just so you can interpret what this and that means regards how it will affect your view through the eyepiece.

Good call, Merlin!

Dave

[admin]

@Dave In Vermont  We have removed a comment from one of your posts. 

This is SGL, please behave appropriately. Supplier bashing is not allowed. 

[Paul73]

Has anyone done any field comparisons  of the cheaper filters? 

Paul