Let's talk filters

[Stardaze]

Sparked through another discussion, I couldn't see a suitable area in the equipment thread, so thought it might be a good topic to discuss here. Mods, feel free to move to the appropriate place.

I've been reading up on filters and will be purchasing both a UHC and O-III this year. As I've had to buy plenty of add-on's, on top of the new scope purchase, and therefore feeling the pinch, inevitably I've considered options away from Astronomik. The 2" versions are preferable, so I've coonsidered the ES filters as an option to get me going, but, inevitably I'll probably end up with the expensive versions at some point, so could this be false economy? If I can wait, buying secondhand makes sense, so it may be that I just buy one quality 2" now, the other later.

The DGM NPD gets rave reviews too from what I've found, but limited supply. 

I've seen these get recommended in one review as a budget option:  https://www.amazon.co.uk/dp/B07CSMH62L/ref=as_li_ss_tl?slotNum=22&s=gateway&keywords=astromania+uhc+filter&language=en_US&sr=8-3&linkCode=g12&linkId=b7906c23da3c7b308bdaaea3203e9a9d&imprToken=dZLR3aiQ2O2DBtR9beRKgg&tag=nightskyadam-21

I've also considered a broadband filter too. The Orion SkyGlow seems to get the plaudits but largely unavailable it appears?

I'd be interested to hear thoughts on the above and whether holding back to spend on a top filter is really what I should be doing. 

 

PS. @John you mentioned that your O-III is in 1.25"? Whats do you use with your Ethos?

Edited June 9, 2020 by Stardaze

[John]

I have a Lumicon O-III in the 2 inch size and an Astronomik O-III in 1.25 inch.

The Ethos eyepieces use the 2 inch filter although the 13, 8 and 6mm are actually 1.25" eyepieces so can use the smaller filter size. To keep things simple I've added 2 inch barrel extenders to those so that I can use 2 inch filters on all of them:

 

[rl]

What is your light pollution like? Do you need a really narrowband filter to cut out streetlights or are you out in the country where a less aggressive approach might be more apt?

As you're probably aware, the narrowband filters do a great job on revealing line emission nebulae at the cost of dimming stars (faint ones to extinction), and all the remaining stars look the same colour. 

The deep sky filters are often enough if you are at a moderate to good site in the first place, they give a useful increase in contrast on emission nebulae without ruining everything else in the field. 

I've had the Lumicon deep sky filter for 35 years and it's still my overall favourite, both for visual and AP. But the Astronomik CLS is also excellent. 

Sorry if I'm teaching granny to suck eggs here. Personally I regard the filter as the least critical link in the chain after the scope and the eyepiece. In my experience most O3 filters give much the same results, as do most deep sky filters.

Personally I like filters that have a hydrogen alpha passband....I reckon I can see dark chocolate browns in the brighter emission nebulae which are supposed to be out of the passband for the rod cells. 

David Knisley did a good comparison:

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

You are obviously fairly close to me...if you want to try a couple for a week or so when the moon is not an issue you're welcome. 

 

Edited June 9, 2020 by rl
link added

[scarp15]

35 minutes ago, Stardaze said:

 

 

I'd be interested to hear thoughts on the above and whether holding back to spend on a top filter is really what I should be doing. 

 

 

Yes definitely, do all your research and keep a watch on the classified used sections on AB&S. My first filter was an Orion Ultra Block, which was used on an old C8. After this I eventually bought at retail a Lumicon 2" OIII filter, now considered a traditional classic and the company has I understand, become credible again for some of the highest quality products. Astronomic and Tele Vue line filters ought to be considered to. Realistically time can be measured in years to gain most of everything you feel you would like, the used market helps, combined with some items at or near retail, research is everything. A high quality OIII filter is highly rewarding and will subsequently gain you years of potentially outstanding observing. Then yes as above, a dark sky location is required to visually capitalise on your investments.  

[Ships and Stars]

After much consideration, I went all Astronomik and use a 2" OIII and OIII/UHC/Hb in 1.25". Didn't bother with any sort of sky-glow or light pollution filters, think the UHC tackles that job better anyway.

In order of most frequently used for me, it's OIII, then Hb, then UHC. Usually the Hb is the least commonly used, but I like hunting for the dark nebulae with mine.

All except the Hb were second-hand due to price. The 2" in particular are not cheap to say the least, and I felt lucky to find an OIII second-hand in like new condition.

The 2" OIII is my fav, especially for larger nebulae. The Veil in particular is just stunning under dark skies with this and a wide low-mag 2" EP. I used the 21E when I had it, but the 20APM will have a turn in about three long months or so!

The Hb works well on the Horsehead Nebula. I usually pair that up with a 17.5mm Morpheus.

Perhaps surprisingly, I don't really use the UHC much, though it's good at revealing different levels of detail on objects like M42, all depends really. One issue I have with my UHC is that the stars will separate into green and red partially-overlapping points of light like there is some difficulty in focusing those two wavelengths in the colour spectrum or something. It's not horrendous, but once you notice it, it becomes more intrusive. Could be something with the f4 scope not merging light rays, but can't remember where I read about this phenomenon. At any rate, I call it the 'Christmas Effect'. 

Because I also use binoculars with filter threads, I'll mix 1.25" filters on different targets, i.e. UHC on one side and OIII on the other, or OIII/Hb, etc. The result is quite interesting, the brain merges the two images and seems to pick the best detail from both, sort of like having a 'super filter' system.

In the future, I'd like to try the cheapest OIII/UHC and Hb that pop up second-hand against the Astronomiks and see if there is really that much difference. Same for a DGM NPB/cheapo brand-x/Astronomik shootout some night. I'd add Lumicon, but I'm hardly rich! 

Someone on here said they could see (detect?) the Horsehead with their cheap Hb, so perhaps I wouldn't sweat it too much if you don't want to fork out for Astronomik/TV/Lumicon at first, but I'm curious what sort of difference there is.

If you buy the top ones though, there's not much second-guessing about quality and if you are getting the best view possible. Some of the cheap filters I hear can be terrible, as is the odd 'good' one.

The DGMs are next on the shopping list, been wanting some for ages. 

If I was starting out, I'd splash out on a good OIII filter in 2" and build from there. The 2" OIII is sort of the workhorse filter for many.

 

Edited June 9, 2020 by Ships and Stars

[Don Pensack]

 

Over the last 3 years, I've tested and reviewed about 52 different nebula filters.

These were the best in the field and in the lab:

Narrowband:

TeleVue BandMate II Nebustar (2018 on)

Astronomik UHC (2017 on)

Lumicon UHC Gen.3 (2018 on)*

O-III:

TeleVue BandMate II O-III (2018 on)*

Astronomik O-III Visual (2017 on)

Lumicon O-III Gen. 3 (2019 on)

H-ß:

TeleVue BandMate II H-ß (2018 on)*

Astronomik H-ß (2017 on)

Orion (US) H-ß (2018 on)

Broadband:

Baader UHC-S (2017 on)*

Lumicon Deep Sky (2016 on)

DGM GCE (2017 on)

Best ones in the lab have a star by them.

 

A lot of other filters failed to live up to their missions, by using too wide a bandwidth, or having a misplaced bandwidth that clipped a line, having a large variation from filter to filter, or failing to cover the necessary wavelengths at all.

My review was of filters for visual use, not photographic.  Photographically, the list would be different.

Brands I tested: Explore Scientific, TeleVue, Astronomik, DGM, Baader, Lumicon, Yulong (StarGuy, Optolong), Sirius Optics, Orion (US), Thousand Oaks.

 

•  

[mikeDnight]

I used to use a 2" Lumicon Olll filter with my 5" Tak many years ago, but in a 5" it blocked out all but the brightest stars. Nebulae like the Veil were spectacular though! So I'd say if you have a large enough aperture, perhaps 8"+, the Olll will be great, but for smaller apertures the UHC has certain advantages, and is very effective.

[Don Pensack]

26 minutes ago, Ships and Stars said:

After much consideration, I went all Astronomik and use a 2" OIII and OIII/UHC/Hb in 1.25". Didn't bother with any sort of sky-glow or light pollution filters, think the UHC tackles that job better anyway.

In order of most frequently used for me, it's OIII, then Hb, then UHC. Usually the Hb is the least commonly used, but I like hunting for the dark nebulae with mine.

All except the Hb were second-hand due to price. The 2" in particular are not cheap to say the least, and I felt lucky to find an OIII second-hand in like new condition.

The 2" OIII is my fav, especially for larger nebulae. The Veil in particular is just stunning under dark skies with this and a wide low-mag 2" EP. I used the 21E when I had it, but the 20APM will have a turn in about three long months or so!

The Hb works well on the Horsehead Nebula. I usually pair that up with a 17.5mm Morpheus.

Perhaps surprisingly, I don't really use the UHC much, though it's good at revealing different levels of detail on objects like M42, all depends really. One issue I have with my UHC is that the stars will separate into green and red partially-overlapping points of light like there is some difficulty in focusing those two wavelengths in the colour spectrum or something. It's not horrendous, but once you notice it, it becomes more intrusive. Could be something with the f4 scope not merging light rays, but can't remember where I read about this phenomenon. At any rate, I call it the 'Christmas Effect'. 

Because I also use binoculars with filter threads, I'll mix 1.25" filters on different targets, i.e. UHC on one side and OIII on the other, or OIII/Hb, etc. The result is quite interesting, the brain merges the two images and seems to pick the best detail from both, sort of like having a 'super filter' system.

In the future, I'd like to try the cheapest OIII/UHC and Hb that pop up second-hand against the Astronomiks and see if there is really that much difference. Same for a DGM NPB/cheapo brand-x/Astronomik shootout some night. I'd add Lumicon, but I'm hardly rich! 

Someone on here said they could see (detect?) the Horsehead with their cheap Hb, so perhaps I wouldn't sweat it too much if you don't want to fork out for Astronomik/TV/Lumicon at first, but I'm curious what sort of difference there is.

If you buy the top ones though, there's not much second-guessing about quality and if you are getting the best view possible. Some of the cheap filters I hear can be terrible, as is the odd 'good' one.

The DGMs are next on the shopping list, been wanting some for ages. 

If I was starting out, I'd splash out on a good OIII filter in 2" and build from there. The 2" OIII is sort of the workhorse filter for many.

 

The red/green split in your UHC is because there is a lot of red transmission in the Astronomik filter.  The TeleVue filter, made by Astronomik, has no red transmission at all.

Though this has a funky effect on the star images, the red does yield a bit more size to the nebula, so it's a trade-off.

The DGM NPB isn't on my list, though I love it, because of its variable manufacturing QC.  If you get a good one, it's fantastic.  The blue-green bandwidth is the narrowest of all the UHC-type filters, and the huge amount of red yields larger sizes to nebulae, sacrificing only a small amount of contrast to do it.  All the stars appear red in the NPB.

The DGM O-II is nothing special, and the VHT has too wide a bandwidth.  It resembles the Astronomik UHC-E.

[Don Pensack]

5 minutes ago, mikeDnight said:

I used to use a 2" Lumicon Olll filter with my 5" Tak many years ago, but in a 5" it blocked out all but the brightest stars. Nebulae like the Veil were spectacular though! So I'd say if you have a large enough aperture, perhaps 8"+, the Olll will be great, but for smaller apertures the UHC has certain advantages, and is very effective.

But do you get a filter to look at stars, or nebulae?  

I do hear you, though.  There are times when I prefer a wider filter to look at an object that is better seen in a narrower filter.  One example is NGC2359, Thor's Helmet, in Canis Major.  It's best with a 11-13nm O-III filter, but because it's in the Milky Way, you lose the context.  So if I'm at a site that already has very dark skies, I'll use a filter like a Baader UHC-S (62nm bandwidth) because, though the nebula becomes a lot harder to see, the stars are still there and the nebula is magnificent with a billion stars in the background.  That doesn't mean I won't go back to the narrower filter to look at striae in the central bubble, however.

Here is a picture of what I mean:   http://www.jburnell.com/NGC2359.html

[Stardaze]

1 hour ago, John said:

I have a Lumicon O-III in the 2 inch size and an Astronomik O-III in 1.25 inch.

The Ethos eyepieces use the 2 inch filter although the 13, 8 and 6mm are actually 1.25" eyepieces so can use the smaller filter size. To keep things simple I've added 2 inch barrel extenders to those so that I can use 2 inch filters on all of them:

 

That's interesting, because I've been sure of a 2" when maybe a 1.25" might get me by for a bit?

50 minutes ago, rl said:

What is your light pollution like? Do you need a really narrowband filter to cut out streetlights or are you out in the country where a less aggressive approach might be more apt?

As you're probably aware, the narrowband filters do a great job on revealing line emission nebulae at the cost of dimming stars (faint ones to extinction), and all the remaining stars look the same colour. 

The deep sky filters are often enough if you are at a moderate to good site in the first place, they give a useful increase in contrast on emission nebulae without ruining everything else in the field. 

I've had the Lumicon deep sky filter for 35 years and it's still my overall favourite, both for visual and AP. But the Astronomik CLS is also excellent. 

Sorry if I'm teaching granny to suck eggs here. Personally I regard the filter as the least critical link in the chain after the scope and the eyepiece. In my experience most O3 filters give much the same results, as do most deep sky filters.

Personally I like filters that have a hydrogen alpha passband....I reckon I can see dark chocolate browns in the brighter emission nebulae which are supposed to be out of the passband for the rod cells. 

David Knisley did a good comparison:

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

You are obviously fairly close to me...if you want to try a couple for a week or so when the moon is not an issue you're welcome. 

 

I'm on the outskirts in a Bortle 5 area, 10 minutes south and I'm into a Bortle 4. I'm using a 10" Bresser dob, currently with mid-range EP's just to paint the picture. It's the skyglow broad band filter that I'm really unsure about. I may take you up on your very kind offer just to be sure 😊

42 minutes ago, Ships and Stars said:

After much consideration, I went all Astronomik and use a 2" OIII and OIII/UHC/Hb in 1.25". Didn't bother with any sort of sky-glow or light pollution filters, think the UHC tackles that job better anyway.

In order of most frequently used for me, it's OIII, then Hb, then UHC. Usually the Hb is the least commonly used, but I like hunting for the dark nebulae with mine.

All except the Hb were second-hand due to price. The 2" in particular are not cheap to say the least, and I felt lucky to find an OIII second-hand in like new condition.

The 2" OIII is my fav, especially for larger nebulae. The Veil in particular is just stunning under dark skies with this and a wide low-mag 2" EP. I used the 21E when I had it, but the 20APM will have a turn in about three long months or so!

The Hb works well on the Horsehead Nebula. I usually pair that up with a 17.5mm Morpheus.

Perhaps surprisingly, I don't really use the UHC much, though it's good at revealing different levels of detail on objects like M42, all depends really. One issue I have with my UHC is that the stars will separate into green and red partially-overlapping points of light like there is some difficulty in focusing those two wavelengths in the colour spectrum or something. It's not horrendous, but once you notice it, it becomes more intrusive. Could be something with the f4 scope not merging light rays, but can't remember where I read about this phenomenon. At any rate, I call it the 'Christmas Effect'. 

Because I also use binoculars with filter threads, I'll mix 1.25" filters on different targets, i.e. UHC on one side and OIII on the other, or OIII/Hb, etc. The result is quite interesting, the brain merges the two images and seems to pick the best detail from both, sort of like having a 'super filter' system.

In the future, I'd like to try the cheapest OIII/UHC and Hb that pop up second-hand against the Astronomiks and see if there is really that much difference. Same for a DGM NPB/cheapo brand-x/Astronomik shootout some night. I'd add Lumicon, but I'm hardly rich! 

Someone on here said they could see (detect?) the Horsehead with their cheap Hb, so perhaps I wouldn't sweat it too much if you don't want to fork out for Astronomik/TV/Lumicon at first, but I'm curious what sort of difference there is.

If you buy the top ones though, there's not much second-guessing about quality and if you are getting the best view possible. Some of the cheap filters I hear can be terrible, as is the odd 'good' one.

The DGMs are next on the shopping list, been wanting some for ages. 

If I was starting out, I'd splash out on a good OIII filter in 2" and build from there. The 2" OIII is sort of the workhorse filter for many.

 

Adding some real world use situations is really helpful, thank you. The veil looks to be at it's highest next month and so I had been thinking of the O-III first as that's my first use I'd like. My 16 gives me 79x so if scrimping, maybe a 1.25" could work here. I'm also thinking well ahead to December when I really want to study M42 with a decent filter for the first time. That seems to be where a UHC just edges it on balance and I'll probably need wider than my 16, so a 2" for that? UHC seems to be the usual recommendation, but most of the things I would like to see do seem to be slightly O-III biased so you're probably right with starting with one.

18 minutes ago, Don Pensack said:

 

Over the last 3 years, I've tested and reviewed about 52 different nebula filters.

These were the best in the field and in the lab:

Narrowband:

TeleVue BandMate II Nebustar (2018 on)

Astronomik UHC (2017 on)

Lumicon UHC Gen.3 (2018 on)*

O-III:

TeleVue BandMate II O-III (2018 on)*

Astronomik O-III Visual (2017 on)

Lumicon O-III Gen. 3 (2019 on)

H-ß:

TeleVue BandMate II H-ß (2018 on)*

Astronomik H-ß (2017 on)

Orion (US) H-ß (2018 on)

Broadband:

Baader UHC-S (2017 on)*

Lumicon Deep Sky (2016 on)

DGM GCE (2017 on)

Best ones in the lab have a star by them.

 

A lot of other filters failed to live up to their missions, by using too wide a bandwidth, or having a misplaced bandwidth that clipped a line, having a large variation from filter to filter, or failing to cover the necessary wavelengths at all.

My review was of filters for visual use, not photographic.  Photographically, the list would be different.

Brands I tested: Explore Scientific, TeleVue, Astronomik, DGM, Baader, Lumicon, Yulong (StarGuy, Optolong), Sirius Optics, Orion (US), Thousand Oaks.

 

•  

Thanks Don, really helpful. The bandmate was the top of the list, just baulking at the initial cost following an expensive few months. Realise they are along time investments though, I'll stick to the 'buy once' philosophy I think. 

Thanks to everyone's input, very interesting and a great insight. 

[Don Pensack]

One thing to note about these filters.

They work by lowering the background brightness several magnitudes while dimming the nebula maybe only 0.1 magnitude.

The contrast enhancement is how they work.

As the magnification increases, the background in the scope dims, as does the nebula.  Above a certain point, the darkening of the background by the filter is small because you can't get darker than black,

but the nebula has dimmed.  This lowers the improvement in contrast and the filters stop being particularly effective.

With narrowband or O-III or H-ß filters, this occurs at about 10x/inch of aperture in the telescope.  That means they will be used at low power and if even your only 2" eyepiece is your low power, then get a 2" filter.

You can always thread it onto a 2" adapter to use with 1.25" eyepieces.

Now, broader filters, like a broadband, can be used at a bit higher magnifications without dimming the objects quite as much--maybe up to 12x-13x/inch of aperture.

But their effects are, at best, somewhat subtle, and only improve contrast a tiny bit.

Edited June 9, 2020 by Don Pensack

[Stardaze]

10 minutes ago, Don Pensack said:

One thing to note about these filters.

They work by lowering the background brightness several magnitudes while dimming the nebula maybe only 0.1 magnitude.

The contrast enhancement is how they work.

As the magnification increases, the background in the scope dims, as does the nebula.  Above a certain point, the darkening of the background by the filter is small because you can't get darker than black,

but the nebula has dimmed.  This lowers the improvement in contrast and the filters stop being particularly effective.

With narrowband or O-III or H-ß filters, this occurs at about 10x/inch of aperture in the telescope.  That means they will be used at low power and if even your only 2" eyepiece is your low power, then get a 2" filter.

You can always thread it onto a 2" adapter to use with 1.25" eyepieces.

Now, broader filters, like a broadband, can be used at a bit higher magnifications without dimming the objects quite as much--maybe up to 12x-13x/inch of aperture.

But their effects are, at best, somewhat subtle, and only improve contrast a tiny bit.

And that's where my 'scrimping' falls down 😂

There's a Televue Bandmate O-III listed badly on a popular auction site. It's listed at 1.25" , at that price point, but, is pictured as a 2"? Only 'good' condition though, which puts me off...

Edited June 9, 2020 by Stardaze

[John]

13 minutes ago, Stardaze said:

And that's where my 'scrimping' falls down 😂

There's a Televue Bandmate O-III listed badly on a popular auction site. It's listed at 1.25" , at that price point, but, is pictured as a 2"? Only 'good' condition though, which puts me off...

Careful ! - the TV Bandmate and Bandmate II's are very different in quality. The II's are fantastic, the originals rather mediocre.

 

[Ricochet]

10 minutes ago, Stardaze said:

And that's where my 'scrimping' falls down 😂

There's a Televue Bandmate O-III listed badly on a popular auction site. It's listed at 1.25" , at that price point, but, is pictured as a 2"? Only 'good' condition though, which puts me off...

It is an original bandmate, not the bandmate type 2 you are looking for. 

[Stardaze]

So the current one (https://www.firstlightoptics.com/televue-filters/tele-vue-bandmate-oiii-filter.html) is not the best model?

[Ricochet]

Just now, Stardaze said:

So the current one (https://www.firstlightoptics.com/televue-filters/tele-vue-bandmate-oiii-filter.html) is not the best model?

The current one is the best model. Look at the writing on the filter itself in the photo. 

[Stardaze]

1 minute ago, Ricochet said:

The current one is the best model. Look at the writing on the filter itself in the photo. 

Just clocked that, as it'a clearer on 365's site. That's next months present sorted then....

https://www.365astronomy.com/televue-bandmate-type-2-h-beta-premium-visual-nebula-filter-2-inch.html

[John]

5 minutes ago, Stardaze said:

Just clocked that, as it'a clearer on 365's site. That's next months present sorted then....

https://www.365astronomy.com/televue-bandmate-type-2-h-beta-premium-visual-nebula-filter-2-inch.html

Slightly worrying that the pic is of an O-III filter but the description is for an H-Beta.

If you buy from there, make sure you know what sort you are buying !

[Stardaze]

5 minutes ago, John said:

Slightly worrying that the pic is of an O-III filter but the description is for an H-Beta.

If you buy from there, make sure you know what sort you are buying !

I'll probably go FLO as usual, might squeeze an APM 13 into the month too..

 

Think I linked the wrong one too @JohnJohn: https://www.365astronomy.com/televue-bandmate-type-2-oiii-premium-visual-nebula-filter-2-inch.html

 

Edited June 9, 2020 by Stardaze

[John]

What scope will these be used in by the way ?

Sorry if you have mentioned it somewhere but I can't recall it (getting old !)

[Stardaze]

10 minutes ago, John said:

What scope will these be used in by the way ?

Sorry if you have mentioned it somewhere but I can't recall it (getting old !)

Bresser 10” 

[Mark at Beaufort]

Just to add to the discussion I have used a number of UHC, O-III and Hb filters.

I currently use an original Lumicon UHC made in Livermore, CA, TeleVue Nebustar Type 2 UHC, Astonomik O-III and a Sky's the Limit Hb - all these are 1.25" which I sometimes use with a 2"/1.25" adapter. I also have some 2" filters - Skywatcher UHC (rarely use) and a Castell O-III which I really rate even though not that expensive - https://www.365astronomy.com/Castell-OIII-Deepsky-Filter-for-2-Inch-Eyepieces.html

 

[Stardaze]

9 hours ago, Mark at Beaufort said:

Just to add to the discussion I have used a number of UHC, O-III and Hb filters.

I currently use an original Lumicon UHC made in Livermore, CA, TeleVue Nebustar Type 2 UHC, Astonomik O-III and a Sky's the Limit Hb - all these are 1.25" which I sometimes use with a 2"/1.25" adapter. I also have some 2" filters - Skywatcher UHC (rarely use) and a Castell O-III which I really rate even though not that expensive - https://www.365astronomy.com/Castell-OIII-Deepsky-Filter-for-2-Inch-Eyepieces.html

 

Do you find a discernible difference between the two UHC’s Mark out of interest?

[Mark at Beaufort]

44 minutes ago, Stardaze said:

Do you find a discernible difference between the two UHC’s Mark out of interest?

The short answer is No. I have had various other UHC filters - Skywatcher, Sky's the Limit and Baader UHC-S but found that the Lumicon and TeleVue gave better contrast. There has been a great deal of debate on Lumicon filters because the company was originally started in Livermore, CA then was sold out and the next batch was not as good. Since then stage 3 has provided a new series which I understand is good. Perhaps @Don Pensackin the States can confirm this situation.

[John]

One way to get an idea how a filter might perform compared with another is to look at the band pass charts for them:

The above is a couple of years out of date now but it shows that there are differences in band pass width, cut-off profiles and maximum transmittance between brands. Where the profiles are relatively close, the visual impact will probably be undetectable but the larger differences do make a difference that can be seen.

Here are similar charts for a group of UHC filters with a bit more information to help interpret them:

 

I have seen profiles for O-III filters which make them practically UHC status and likewise UHC's that are moving into the broadband territory.

Apologies if the above is "data overload" on filters