54 replies to this topic

[thecelloronin]

Besides offering some contrast boost while viewing some nebulae at smaller exit pupils and filtering out light pollution which today's LEDs don't actually emit, is there any argument for a broadband filter in telescopes or binoculars?

[Hesiod]

Well, I do not know if would call a "proper" UHC-type filter to be "broad band".

These are nebular filters, and are pretty useful on bright emission nebulae having other lines than the OIII, and if want to exploit a bit more magnifications than with the OIII filter.

"Filtering" LP is not exactly their purpose and indeed IME are more rewarding the darker your sky is.

 

There are also "broadband" LP-suppression filters but IME those are essentially for imaging.

They help (and quite a lot) when dealing with light pollution gradients; the milder ones (e.g. Astroklar) are probably designed for landscape/oneshot pictures to get a more pleasant-looking sky without having to dabble too much with the WB

[steveward53]

They make a great alternative to the Baader Continuum filter when viewing/imaging the Sun in whitelight , especially as most folk already have one in their 'toolbox' therefore saving themselves £100 or so ... 

[thecelloronin]

Well, I do not know if would call a "proper" UHC-type filter to be "broad band".

These are nebular filters, and are pretty useful on bright emission nebulae having other lines than the OIII, and if want to exploit a bit more magnifications than with the OIII filter.

"Filtering" LP is not exactly their purpose and indeed IME are more rewarding the darker your sky is.

 

There are also "broadband" LP-suppression filters but IME those are essentially for imaging.

They help (and quite a lot) when dealing with light pollution gradients; the milder ones (e.g. Astroklar) are probably designed for landscape/oneshot pictures to get a more pleasant-looking sky without having to dabble too much with the WB

Agreed, a proper UHC like, well, Lumicon's UHC or DGM's NPB are narrowband and quite functional for visual. I was speaking more to the "UHC" filters that are actually broadband filters. UHC-E, S, plus generic "nebula filters" and even deep sky filters–that sort of thing.

Edited by thecelloronin, 02 February 2022 - 03:20 AM.

[havasman]

I have wondered how those less discriminating UHC filters might perform in a pair of the modern low power very wide field binoculars. But not enough to try it out.

[thecelloronin]

I have wondered how those less discriminating UHC filters might perform in a pair of the modern low power very wide field binoculars. But not enough to try it out.

Care to speculate out loud?

[havasman]

Well I had a pair of holders machined for the 10x50's but a matched pair of Lumicon UHC's mostly just resulted in an overly dim field. But the exit pupil on those little widefields is an inch or so wide, more or less, and gently filtering the background with those much less effective filters might give just a little boost to the apparent contrast without wiping out the entire field. Or not.

 

Like I said, it was never interesting enough to actually try out. Plus I haven't been anywhere dark enough to give it a decent chance since it occurred to me. 

 

Otherwise no, those have no worth to me. I've tried them. Folks say they like 'em for hi mag use. I have used my filters, particularly the O-III, at very high magnifications in the Starmaster with good results.

Edited by havasman, 02 February 2022 - 04:02 AM.

[Miranda2525]

Besides offering some contrast boost while viewing some nebulae at smaller exit pupils and filtering out light pollution which today's LEDs don't actually emit, is there any argument for a broadband filter in telescopes or binoculars?

I find them totally useless for visual use. Zero enhancement.

Edited by Miranda2525, 02 February 2022 - 05:28 AM.

[MrJones]

I use mine (Lumicon Deep Sky) a lot. I like it mostly on brighter objects to keep the view still close to no-filter but enhancing nebulosity while dimming stars just a little. I also really like it with guests and the brighter showpiece nebulae. It makes them stand out a little more even with less than ideal viewing conditions and doesn't dim the view and stars as drastically as UHC and OIII. I've had guests compare say M27 and M57 with and without the Deep Sky filter many times and no one ever prefers the unfiltered views. There are other more specific uses such as with M20 too.

Edited by MrJones, 02 February 2022 - 02:36 PM.

[emilslomi]

I enjoy my Baader UHC a lot - for the same reasons mentioned by MrJones. The two bands of the Baader are quite wide. Nebulae are enhanced a bit, while the stars are not dimmed a lot. Milage varies with aperture, magnification and sky quality.

 

Emil

[PNW]

I have a SVbony UHC filter that could be classified as a broadband UHC filter. It enhances the red of carbon stars, but doesn't show much on other objects.

[MrJones]

I have a SVbony UHC filter that could be classified as a broadband UHC filter. It enhances the red of carbon stars, but doesn't show much on other objects.

Yes - great for carbon stars!

[Simoes Pedro]

A UHC has a significant noticeable impact in many nebula. Sometimes it is the difference between seeing it, and not seeing.

 

Nowadays, UHC are not all the same. Their bandwidth can change quite a bit. I have a Lumicon one.

[PJBilotta]

There's really no such thing as a broadband UHC filter. It's either/or.

True UHCs are narrow band filters - such as the Lumicon UHC, Orion Ultrablock and DGM NBP. They pass only a very narrow range and are still very beneficial for visual use. Though LEDs reduce their effectiveness, remember that your light pollution is a soup of many different light sources, and a true UHC will still block the others. They work quite well in my Bortle 6 skies.

Any so-called "UHC" filter that has a broad band pass is just a basic broadband filter labeled as a UHC for marketing purposes. This includes most of the others out there, and while they may enhance contrast slightly, they are of little benefit these days.

Don's fantastic Guile to Filters at the top of this forum is the best source for determining which ones are really UHCs.

[David Knisely]

There's really no such thing as a broadband UHC filter. It's either/or.

True UHCs are narrow band filters - such as the Lumicon UHC, Orion Ultrablock and DGM NBP. They pass only a very narrow range and are still very beneficial for visual use. Though LEDs reduce their effectiveness, remember that your light pollution is a soup of many different light sources, and a true UHC will still block the others. They work quite well in my Bortle 6 skies.

Any so-called "UHC" filter that has a broad band pass is just a basic broadband filter labeled as a UHC for marketing purposes. This includes most of the others out there, and while they may enhance contrast slightly, they are of little benefit these days.

Don's fantastic Guile to Filters at the top of this forum is the best source for determining which ones are really UHCs.

The term "UHC" came from the original Lumicon company, based in Livermore, California and run by Jack Marling in the late 1970's into the 1980's.  Lumicon originally sold things mainly for the astrophotography community, including gas-hypering equipment and supplies for film, diagonals and adaptors, and retail eyepieces from other companies like Tele Vue, but in the early 1980's, they started marketing the interference filters which later made them famous.  With the original Lumicon UHC, Marling basically created the first truly effective narrow-band nebula filter that I had ever seen that made it on the market.  The UHC term stood for "Ultra High Contrast", and for those of us who were the first to use that nebula filter, the name really described what we saw!  Unfortunately, only a few years later, other companies basically ripped-off the UHC term and stuck it on their various filters, some of which bore little or no performance or optical resemblance to the original Lumicon UHC model.  Although the UHC term was a trademark registered to Lumicon, Jack mainly thought that with his limited market and funds, challenging all these rip-off events in court was simply not worth the legal effort, so, other than some support we as amateurs gave him early on, this theft of the name continued even to this day.  This is why I term the "UHC-like" filters that just pass the OIII and H-Beta lines and little else to be Narrow-band nebula filters and not "UHC" filters, as now, that term often has little useful meaning.  To avoid the labeling and function confusion, I just class filters into three basic groups: Broad-band (LPR) filters, Narrow-band nebula filters, and Line nebula filters.   Clear skies to you.  

Edited by David Knisely, 03 February 2022 - 10:50 AM.

[PJBilotta]

Excellent distinction and clarification, David.

[Mitrovarr]

I find them occasionally useful with clusters with associated nebulosity, where you might want an advantage but not to mess with the cluster too much. Or for small telescopes where a true narrowband filter might just dim things too much.

[RLK1]

The term "UHC" came from the original Lumicon company, based in Livermore, California and run by Jack Marling in the late 1970's into the 1980's.  Lumicon originally produced things mainly for the astrophotography community, including gas-hypering equipment and supplies for film, diagonals and adaptors, and retail eyepieces from other companies like Tele Vue, but in the early 1980's, they started marketing the interference filters which later made them famous.  With the original Lumicon UHC, Marling basically created the very first truly effective narrow-band nebula filter that made it on the market.  The UHC term stood for "Ultra High Contrast", and for those of us who were the first to use that nebula filter, the name really described what we saw!  Unfortunately, only a few years later, other companies basically ripped-off the UHC term and stuck it on their various filters, some of which bore little or no performance or optical resemblance to the original Lumicon UHC model.  Although the UHC term was a trademark registered to Lumicon, Jack mainly thought that with his limited market and funds, challenging all these rip-off events in court was simply not worth the legal effort, so, other than some support we as amateurs gave him early on, this theft of the name continued even to this day.  This is why I term the "UHC-like" filters that just pass the OIII and H-Beta lines and little else to be Narrow-band nebula filters and not "UHC" filters, as now, that term often has little useful meaning.  To avoid the labeling and function confusion, I just class filters into three basic groups: Broad-band (LPR) filters, Narrow-band nebula filters, and Line nebula filters.   Clear skies to you.  

I know it's been discussed in the past but Leo Henzl teamed up with Daystar and produced the first narrowband and broadband filters that were marketed in the USA and Henzl sold them via his ads in Sky & Telescope magazine. These filters predated Lumicon. 

[David Knisely]

I know it's been discussed in the past but Leo Henzl teamed up with Daystar and produced the first narrowband and broadband filters that were marketed in the USA and Henzl sold them via his ads in Sky & Telescope magazine. These filters predated Lumicon. 

Those few I talked to at that time who had seen a few of the early products didn't think the early broad-band and nebula filters were all that effective, although I personally had never gotten to see a Daystar one, so I can't say that this is completely accurate.  I was initially not a fan of filters until saw my first Lumicon UHC and Deep-sky filters at a club star party in 1980 or 81.  Looking back into my Sky and Telescope issues, these Daystar filters don't seem to have gotten a lot of press or advertisement, but I do see the words "Nebula Filters" listed in a Daystar add in a 1982 issue of Sky and Telescope.  Early on at conventions, the only filters I saw tended to be those from Lumicon (other than the DayStar solar H-alpha filters which I first encountered in the mid 1980's (bought a T-Scanner in 1988).  I will modify my original statement to say that the UHC was the first truly effective narrow-band nebula filter that I had ever seen.  Clear skies to you. 

Edited by David Knisely, 03 February 2022 - 03:29 AM.

[Miranda2525]

I find them occasionally useful with clusters with associated nebulosity, where you might want an advantage but not to mess with the cluster too much. Or for small telescopes where a true narrowband filter might just dim things too much.

Not if the exit pupil is right.

[jcj380]

The term "UHC" came from the original Lumicon [...]  in the early 1980's, they started marketing the interference filters which later made them famous.  With the original Lumicon UHC, Marling basically created the first truly effective narrow-band nebula filter that I had ever seen that made it on the market.  The UHC term stood for "Ultra High Contrast", and for those of us who were the first to use that nebula filter, the name really described what we saw! 

I'm glad I kept my Lumicon all these years. 

Edited by jcj380, 03 February 2022 - 08:23 AM.

[RLK1]

Those few I talked to at that time who had seen a few of the early products didn't think the early broad-band and nebula filters were all that effective, although I personally had never gotten to see a Daystar one, so I can't say that this is completely accurate.  I was initially not a fan of filters until saw my first Lumicon UHC and Deep-sky filters at a club star party in 1980 or 81.  Looking back into my Sky and Telescope issues, these Daystar filters don't seem to have gotten a lot of press or advertisement, but I do see the words "Nebula Filters" listed in a Daystar add in a 1982 issue of Sky and Telescope.  Early on at conventions, the only filters I saw tended to be those from Lumicon (other than the DayStar solar H-alpha filters which I first encountered in the mid 1980's (bought a T-Scanner in 1988).  I will modify my original statement to say that the UHC was the first truly effective narrow-band nebula filter that I had ever seen.  Clear skies to you. 

To clarify: both Henzl's narrowband and broadband filter were sold and marketed by him and not by daystar so one would see his ads prior to those from others, including either lumicon or daystar. I viewed through one of Henzl's prototypes at Mt Pinos when I was a teenager and that was prior to it going to market. I eventually purchased one and used it successfully for years in my homemade 8" f6 newt. I gave it to a relative and it's now somewhere in use in the Negev desert. It's really not much different in performance from the ones that are available today.

[russell23]

In general, I use broadband filters at smaller exit pupils ... less than 1.5mm. At larger exit pupils I use narrowband filters.

[RLK1]

To clarify: both Henzl's narrowband and broadband filter were sold and marketed by him and not by daystar so one would see his ads prior to those from others, including either lumicon or daystar. I viewed through one of Henzl's prototypes at Mt Pinos when I was a teenager and that was prior to it going to market. I eventually purchased one and used it successfully for years in my homemade 8" f6 newt. I gave it to a relative and it's now somewhere in use in the Negev desert. It's really not much different in performance from the ones that are available today.

Here's a previous thread on the origins of the modern day narrowband filter for those who are interested:

https://www.cloudyni...owband-filters/

In particular, note posts # 3, 6, 17 & 18. 

[Starman1]

I have used broadband filters in all sorts of light environments, and I have found they are:

--basically only useful in already quite dark skies.

Where no extra light in the sky causes a loss of contrast greater than the gain with the filter.

--useful to turn of the contrast 1 click without dimming the stars significantly

It gives a view, as one example, of NGC2359 hanging in space in front of thousands of faint background stars, when a narrow O-III filter shows more nebula detail, but kills the stars in the background.

--usable at fairly high powers (I use mine up to about 16x/inch of aperture).

I would not use a narrowband or line filter at that high a magnification.

--useful for nebulae with both blue reflection components and H-α and H-ß emission.

M20 in my scope is best with the Baader UHC-S broadband because both parts are visible, and enhanced.