Choice of UHC Filter?

[Mak the Night]

Although light pollution isn’t a huge problem for me as I live on the edge of the green belt, I have been considering investing in a decent 1.25“ UHC filter.

I don’t have much experience using filters apart from occasionally utilising or experimenting with the eight Kodak Wratten colour filters consisting of an #80A Blue, #58A Green, #56 Light Green, #25 Red, #21 Orange, #12 Yellow and a #0.9 Moon Filter that were originally part of a Celestron kit. Of those I have made some use of the #21 Orange filter for early morning daylight lunar viewing.

My basic Celestron Wratten filters

So far I have considered the TeleVue NebuStar, Astronomik CLS Light Pollution Filter (I can’t find a normal Astronomik UHC filter at the moment) and the Baader UHC-S Filter (from FLO) as the most likely candidates. I plan to use the filter with a 102mm Mak, bearing in mind I will be getting a 9.25“ SCT early next year though. 

Has anyone with experience of UHC filters any thoughts on any of these or similar UHC filters?

[jetstream]

I purchased a middle of the road quality filter a couple of years ago and it underperforms. My suggestion is to find out which manufacturers test each one of their filters individually and give the info either with the filter or if you contact them. My poor one was batch tested I presume.

[Mak the Night]

I purchased a middle of the road quality filter a couple of years ago and it underperforms. My suggestion is to find out which manufacturers test each one of their filters individually and give the info either with the filter or if you contact them. My poor one was batch tested I presume.

That's why the TeleVue NebuStar is in the front running at the moment, as I assume that their QC is the same as their EP's.  Astronomik seem very popular though, and it's around the same price as the TV. I'm not sure about the Baader. Explore Scientific make a UHC filter for less than half the price of the TeleVue or Astronomik filters and they claim they are individually tested. 

http://www.telescopehouse.com/acatalog/info-0310215.html

[jetstream]

The bandwidth and where the bandwidth is placed is hugely important, researching some numbers helps bring some sense to it. What are the bandwiths and locations for the filters you mention? Here is a good link. http://www.reinervogel.net/index.html?/Filter/Filter_UHC.html

[Mak the Night]

The bandwidth and where the bandwidth is placed is hugely important, researching some numbers helps bring some sense to it. What are the bandwiths and locations for the filters you mention? Here is a good link. http://www.reinervogel.net/index.html?/Filter/Filter_UHC.html

Thanks. As far as I can tell most UHC or broadband/nebular filters seem to be similar in their filtering capabilities and transmission of H-alpha, H-beta, and O III. I would have assumed that the three I mentioned (TeleVue, Astronomik and Baader) were more similar than they were different. 

[YKSE]

UHC filter is invented by Lumicon,  and they're the best without question, here's Lumicon's paper about filter's use and specification.

As can be seen in page 4-5, the Lumicon's UHC has bandpass width 22-26nm, that's the HWB measured in Reiner Vogel page provided by Gerry above, wider pass band make filter less effectively. Those UHC filters have pass band width in 50-60nm range work more likely in the range of a green filter.

[John]

I use a Lumicon O-III filter and an Omega DGM NBP filter. The latter is a UHC-type filter. Both are pretty much as good as these things get from my experience using them and reports from others.

Filters is one accessory where Tele Vue would not be top of my list to be honest with you. Their quality will be good of course but their narrowband and line filters tend to have rather wide band pass widths than are considered optimum with medium and larger aperture scopes.

A rather good but less expensive UHC type filter that I've owned in the past is the Orion (USA) Ultrablock. The filter guru on the "Cloudynights" forum, David Knisely rates those highly as well.

[Mak the Night]

UHC filter is invented by Lumicon,  and they're the best without question, here's Lumicon's paper about filter's use and specification.

As can be seen in page 4-5, the Lumicon's UHC has bandpass width 22-26nm, that's the HWB measured in Reiner Vogel page provided by Gerry above, wider pass band make filter less effectively. Those UHC filters have pass band width in 50-60nm range work more likely in the range of a green filter.

OK, thanks for the information.

[Mak the Night]

I use a Lumicon O-III filter and an Omega DGM NBP filter. The latter is a UHC-type filter. Both are pretty much as good as these things get from my experience using them and reports from others.

Filters is one accessory where Tele Vue would not be top of my list to be honest with you. Their quality will be good of course but their narrowband and line filters tend to have rather wide band pass widths than are considered optimum with medium and larger aperture scopes.

A rather good but less expensive UHC type filter that I've owned in the past is the Orion (USA) Ultrablock. The filter guru on the "Cloudynights" forum, David Knisely rates those highly as well.

OK. thanks for the info, it's very interesting. I'm particularly interested in what you have to say about TV filters as they don't seem to be as popular as other types. I'll have to look at Lumicon filters. I've heard a lot of good things about some of the Orion Ultrablock filters.  

[jetstream]

Well I hate to bring this up again- and I must have got a poor one, but my Ultrablock is not so good. I think it cuts out a pile of Hb and it acts like a very wide OIII with lousy transmission.IMHO. I heard the earlier Ultrablocks were much better.

In my very limited experience I would now only consider the NPB, Lumicon and perhaps the Astronomik( after an email to them). I don't mind spending money but I hate wasting it...

[Stu]

Thanks. As far as I can tell most UHC or broadband/nebular filters seem to be similar in their filtering capabilities and transmission of H-alpha, H-beta, and O III. I would have assumed that the three I mentioned (TeleVue, Astronomik and Baader) were more similar than they were different.

I don't think that's necessarily the case. UHCs seem to have quite a wide variation in band pass between brands. This is a useful site:

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

Gerry's point about individually tested filters versus batch tested is very valid. They do vary quite a bit. I know the Skywatcher OIII filter I had was no where near as good as the Lumicon. I think I got lucky with my transmission specs though, above 98% for the three bands on my UHC

[Mak the Night]

Well I hate to bring this up again- and I must have got a poor one, but my Ultrablock is not so good. I think it cuts out a pile of Hb and it acts like a very wide OIII with lousy transmission.IMHO. I heard the earlier Ultrablocks were much better.

In my very limited experience I would now only consider the NPB, Lumicon and perhaps the Astronomik( after an email to them). I don't mind spending money but I hate wasting it...

OK, thanks for that. I beginning to think the Lumicon 1.25" UHC nebula filter is the best option.

[Mak the Night]

I don't think that's necessarily the case. UHCs seem to have quite a wide variation in band pass between brands. This is a useful site:

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

Gerry's point about individually tested filters versus batch tested is very valid. They do vary quite a bit. I know the Skywatcher OIII filter I had was no where near as good as the Lumicon. I think I got lucky with my transmission specs though, above 98% for the three bands on my UHC

Thanks that's really interesting. It seems the Lumicon is emerging as the favourite. I've found a  Lumicon 1.25" UHC nebula filter for around a hundred quid which is only a tad more expensive than the TeleVue. 

[RikM]

I have the Astronomik UHC and am very happy with it indeed. I have compared it to SkyWatcher, and Castel UHCs and an Orion Ultrablock and I prefer the Astronomik to any of those. It enhances the contrast without the view loosing clarity, which the other filters seemed to do to my eyes. I haven't had the opportunity to compare to a Lumicon UHC filter though.

[Mak the Night]

I have the Astronomik UHC and am very happy with it indeed. I have compared it to SkyWatcher, and Castel UHCs and an Orion Ultrablock and I prefer the Astronomik to any of those. It enhances the contrast without the view loosing clarity, which the other filters seemed to do to my eyes. I haven't had the opportunity to compare to a Lumicon UHC filter though.

The Astronomik UHC seems very good from what I've read. Although I think the Lumicon will be the one I'll get. 

[YKSE]

I don't think that's necessarily the case. UHCs seem to have quite a wide variation in band pass between brands. This is a useful site:

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

Gerry's point about individually tested filters versus batch tested is very valid. They do vary quite a bit. I know the Skywatcher OIII filter I had was no where near as good as the Lumicon. I think I got lucky with my transmission specs though, above 98% for the three bands on my UHC

That's quite extensive test of filters, even though it might be of older filters. Reiner Vogel's tests seem to extend longer period of time, some are quite new.

I have the Astronomik UHC and am very happy with it indeed. I have compared it to SkyWatcher, and Castel UHCs and an Orion Ultrablock and I prefer the Astronomik to any of those. It enhances the contrast without the view loosing clarity, which the other filters seemed to do to my eyes. I haven't had the opportunity to compare to a Lumicon UHC filter though.

Yes, as can be seen in Reiner Vogel's tests, Astronomik filters are getting closer and closer to Lumicon's band pass width and transmission rate(lumicon is getting better too), my Astronimik UHC has the following graph:

Over 96% transmission rate for the key  wave lengths and band pass width just under 26nm. good durability and better supression of artificially lights in 370nm to 400nm is good enough for me.

[Stu]

That's quite extensive test of filters, even though it might be of older filters. Reiner Vogel's tests seem to extend longer period of time, some are quite new.

Yes, as can be seen in Reiner Vogel's tests, Astronomik filters are getting closer and closer to Lumicon's band pass width and transmission rate(lumicon is getting better too), my Astronimik UHC has the following graph:

Astronomic_UHC.png

Over 96% transmission rate for the key wave lengths and band pass width just under 26nm. good durability and better supression of artificially lights in 370nm to 400nm is good enough for me.

Interesting read Yong. It seems that the eye's sensitivity is very low in those areas 370 to 420nm) so perhaps not as important as a tight and sharp cut off around the target spectral peaks? That seems to be what he is saying as I read it?

http://www.reinervogel.net/index_e.html

[YKSE]

I think you're right,  Stu.

[John]

In terms of effectiveness at the eyepiece, I tend to look for a sharp cutoff at the edges of the transmission band as much as the % transmitted. I think it's that sudden cutoff that delivers the best contrast enhancement rather than those where there is a more gradual slope.

To put it another way, flat tops = good, sharp points = not so good

[Dave In Vermont]

And now for the ubiquitous and excellent contributions of David Knisely, a member of the Prairie Astronomy Club, which anyone considering using filters would find very useful:

http://www.prairieastronomyclub.org/resources/by-dave-knisely/filter-performance-comparisons-for-some-common-nebulae/

And more -

http://www.prairieastronomyclub.org/resources/by-dave-knisely/useful-filters-for-viewing-deep-sky-objects/

<pant> <pant> ..... And yet more!

http://www.prairieastronomyclub.org/resources/by-dave-knisely/some-available-light-pollution-and-narrow-band-filters/

All of the above are by David of the Prairie and a highly respected 'expert' on filters and their uses.

Enjoy!

Dave

[bingevader]

The ES filters are also individually tested and come with their own test sheet.

[Stu]

In terms of effectiveness at the eyepiece, I tend to look for a sharp cutoff at the edges of the transmission band as much as the % transmitted. I think it's that sudden cutoff that delivers the best contrast enhancement rather than those where there is a more gradual slope.

To put it another way, flat tops = good, sharp points = not so good

Yep, and the Lumicon delivers a sharp cutoff as well as high transmission

[John]

And now for the ubiquitous and excellent contributions of David Knisely, a member of the Prairie Astronomy Club, which anyone considering using filters would find very useful:

http://www.prairieastronomyclub.org/resources/by-dave-knisely/filter-performance-comparisons-for-some-common-nebulae/

And more -

http://www.prairieastronomyclub.org/resources/by-dave-knisely/useful-filters-for-viewing-deep-sky-objects/

<pant> <pant> ..... And yet more!

http://www.prairieastronomyclub.org/resources/by-dave-knisely/some-available-light-pollution-and-narrow-band-filters/

All of the above are by David of the Prairie and a highly respected 'expert' on filters and their uses.

Enjoy!

Dave

Excellent resources above.

David K does not rate the Astronomik O-III too much though which is different to my experience with them.

[Mike73]

There are just too many reviews where the NPB and Lumicon UHC have been tested and the NPB has just edged out the UHC's in contrast. Even though the Lumicon UHC has the better OIII transmission the NPB still comes out on top, figure that one out!?  

Seeing colour in M42 and noticing a huge cloud of gas around M17 were both things I had never noticed before with my old Astronomik UHC.

The NPB also delivers a more of a natural appearance, almost as if you aren't using a filter at all (although I think the new 'improved' NPB isn't quite as neutral as the old one).

I like seeing stars with my NPB, just look how many PN's have nearby OC's. Both Astronomik and Lumicon slightly dim those star fields.

The Lumicon OIII is still widely regarded as the best OIII but for me at least the NPB delivers views which the Lumicon UHC doesn't and cant. 

[Mrbloke]

With all the 'best UHC filter' threads that are out there the concensus is that you can't go wrong with the NPB, lumicon or astronomik versions. I would still like to test them against my explore scientific one though, as a newcomer to the market no one has done a like for like test yet.