Would UHC filter help

[LDW1]

2 hours ago, Don Pensack said:

Pretty much agree.  I either use no filter or the DGM NPB on that one, though the Baader UHC-S adds just a bit of contrast enhancement and makes the image a tad better than no filter at all.

I don't disagree with LDW1--the Baader UHC-S is the only broadband in my filter box, and in dark skies it is my go-to filter for M20 because it doesn't kill the reflection nebula like the narrowbands do.

Normally, in dark skies, M42/43 is so bright it damages my night vision.  It's hard to see that a filter is needed, which is why turning up the contrast just a tad with the broadband works well.

When a nebula is as bright as M42/43, maximal contrast might not be needed.

The choice of filter can be an aesthetic choice instead of maximum contrast, even on the fainter stuff.  It depends.

Though a narrow O-III filter really is what is needed on NGC2359 (Thor's Helmet), I often prefer the view in the Baader UHC-S because the nebula sits in an incredibly rich area of the Milky Way.

Seeing the nebula seemingly hanging in space in front of thousands of background stars is a wonderful view, even if I pop in a narrow O-III to actually study striae in the bubble.

 

Different views require different filters.  I've whittled my filter collection down from 52 to only 13 now, but it's getting hard for me to decide which of the remaining ones have to go.

 

 

Well said based on your extensive experience and like to experiment a bit !

[jetstream]

2 hours ago, Stardaze said:

I was going to plumb for the TeleVue Nebustar II John. But wondered if that specific target would work better with something else.

In the end you will get both the OIII and UHC type and your on the right track with the new TV filters IMHO. I had mine tested before they were sent to me and they tested well indeed.

The lighter the skies the more the OIII comes in IMHO. In dark skies I flick back and forth with my filter slide to see whats responding to what.

[Stardaze]

36 minutes ago, jetstream said:

In the end you will get both the OIII and UHC type and your on the right track with the new TV filters IMHO. I had mine tested before they were sent to me and they tested well indeed.

The lighter the skies the more the OIII comes in IMHO. In dark skies I flick back and forth with my filter slide to see whats responding to what.

I only have an Astronomik O-III at the moment so wanted to add the TV UHC before Xmas. I might add the Baader too then .

[jetstream]

21 minutes ago, Stardaze said:

I only have an Astronomik O-III at the moment so wanted to add the TV UHC before Xmas. I might add the Baader too then .

How old is the OIII?

[Stardaze]

9 minutes ago, jetstream said:

How old is the OIII?

Bought secondhand but I don’t think it’s very old. 

[Louis D]

4 hours ago, Stardaze said:

What's your go-to filter for Orion please? Be interested to know. 

Generally none, but my 1990s Lumicon OIII will show the faint outer edges that blend into the sky-glow.

[jetstream]

3 minutes ago, Stardaze said:

Bought secondhand but I don’t think it’s very old. 

The reason I ask is that some older ones were a bit wider than the newest ones and you can check with Gerd using the serial number- he is vg to deal with.

[jetstream]

1 hour ago, jetstream said:

The lighter the skies the more the OIII comes in IMHO

I need to clarify- I mean that in light skies the OIII will "give" better contrast. An OIII in dark skies is superb.

[Louis D]

You also have to watch out for "rust"/soft coating failure in some of the older Lumicon OIIIs:

[Ships and Stars]

1 hour ago, Louis D said:

You also have to watch out for "rust"/soft coating failure in some of the older Lumicon OIIIs:

 

My first filter was off ebay, an old Lumicon OIII. The coating had heavy rust as you say - it was very mottled and just looked awful. The seller refunded me and said keep it. I still have it somewhere. Nothing against Lumicon at all, I just bought an ancient one on a gamble.

After that I lucked out on a nearly new 2" Astronomik OIII on ABS which is brilliant, then slowly added 1.25" OIII/Hb/UHC Astronomiks. A couple of weeks ago I picked up the 1.25" Nebustar II, a winner, though the normal Astronomik filters are excellent IMHO.

An interesting observation - I was using my Apollo 15x70s the other night with the Nebustar on one side and UHC on the other,and looked at an aerial tower with red lights in the far distance to focus my bins. The UHC showed the red lights, in the Nebustar, total and utter darkness - the red was completely blocked by the Nebustar but plain as day in the UHC. The effect was pretty startling when using both eyes! Does show how effective the Nebustar is at blocking reds. 100% effective in fact...

Any of the Astronomiks OIII/Hb/UHC seem to be excellent filters, though I haven't tried the others. The DGM NPB has always intrigued me, as has the Baader UHC-S or Astronomik UHC-E as a wider sort of medium band filter for binoculars mainly.

I think UHC filters get a lot of use for light-polluted areas, I do the same, but in fact under dark skies they come into their own. The NAN through binoculars with UHC was mesmerising a few weeks ago, just plain as day. What a difference it made.

 

[John]

I had the DGM NBP filter for a while. It is a really effective UHC filter, the best of that filter class that I've used in fact. It does great things with the Orion Nebula extending the "wings" greatly as they curve around and almost seem to meet each other.

The Dumbbell Nebula looks really three dimensional with the NBP filter.

The only downside with it, or at least the version of it that I had, was the marked splitting of stars into multiple colours. Most narrowband and line filters that I've used do this to some extent but my NBP did it more than any that I've used, to the point where it became distracting.

Perhaps the latest versions of the DGM NBP have tamed this effect ?. I hope so because otherwise it seemed a very effective UHC type filter.

 

 

[globular]

31 minutes ago, John said:

I had the DGM NBP filter for a while...
The only downside with it, or at least the version of it that I had, was the marked splitting of stars into multiple colours.

I've noticed a very slight colour splitting of very bright starts a couple of times - but only when the nebulosity doesn't improve with the filter.
When it does I'm probably taking in the nebula too much to notice.  Everything is so new and exciting to me.
I'll make a point to look out for this more carefully next time out.

[John]

1 hour ago, globular said:

I've noticed a very slight colour splitting of very bright starts a couple of times - but only when the nebulosity doesn't improve with the filter.
When it does I'm probably taking in the nebula too much to notice.  Everything is so new and exciting to me.
I'll make a point to look out for this more carefully next time out.

I expect it up to a point with O-III and UHC filters but, for me, the NBP just took it a little too far. The effect of the filter on nebulosity though was really nice so I'm in two mins whether I should have held onto it. Maybe I'll get a new one and see if the latest coating tech / glass polishing has reduced the effect ?

 

[Don Pensack]

1 hour ago, John said:

I expect it up to a point with O-III and UHC filters but, for me, the NBP just took it a little too far. The effect of the filter on nebulosity though was really nice so I'm in two minds whether I should have held onto it. Maybe I'll get a new one and see if the latest coating tech / glass polishing has reduced the effect ?

 

The DGM NPB has a nearly unrestricted red-orange peak and a red peak after that.

It has pretty close to the narrowest of all UHC-type filters in the Blue-green (mine was 21nm)

Because the blue-green bandwidth is so narrow, and the red bandwidth so wide, stars will appear red.  This annoys some people, but not all.

But if it is nebulae you are looking for and at, the DGM is an excellent filter.

 

If you get a good one.  They seem to vary a bit in bandwidth placement in the spectrum, which seems to result in a variation in the % of transmission at the 500.7nm O-III line.  This variation doesn't render the filter ineffective, however.

 

Why the red when filters like the TeleVue Nebustar II and Lumicon UHC have none?

Astronomik aims to be useful for imaging too, by having a high red output at H-α, S-II and N-II wavelengths, but the red starts so deep into the red there is just a trace of red in the star images.

But the DGM starts its red transmission at a lower wavelength and covers a lot more visible reddish wavelengths.

 

Dan McShane explains it this way:

Every nebula's brightness is a combination of its intrinsic emission AND the brightness of the sky overlaying it.  Reducing the brightness of the background will increase contrast between the nebula and the sky.

So keeping the bandwidth narrow in the range of maximum nighttime sensitivity of the eye (~450-550nm) is important.

But eliminating the red wavelengths, where the nebulae emit a lot of energy (maybe MOST energy), when our eye is relatively insensitive to those colors, doesn't make sense.

Plus, there is brightness from the night sky in those long wavelengths, making the nebula even brighter.  Yes, it sacrifices a bit of contrast by allowing so much light to come through the filter.

But it is at wavelengths we see only dimly if at all, and those wavelengths make the nebula appear larger and a bit brighter.

 

Is this true, i.e. does it work?  

Well, visually, and used at truly dark sites, I can say yes, it does work.  On the super-bright nebulae like M42/43, it reveals reds in the nebula you might not see in another filter.

It also makes nebulae like M8, M17, and M16 appear larger than any other UHC filter I've tried.  I would credit that to the narrowness of the blue-green bandwidth (it even outperforms some O-III filters on O-III targets)

but for the fact it allows me to see some reds in M8, M20, M17, M42, and even M27 that other filters do not.

But, comparing the TV, the Astronomik, the Lumicon, and 3 others on M17, the DGM was simply the most amazing of the bunch, where the "Swan" was maybe 10% of the visible nebula (which went way outside

the 45' field), and nebulosity was traceable all the way to M16, verifying that M16 and M17 are merely the brightest points in a very large nebula several degrees wide.  and it revealed, one especially transparent night,

a pink color across much of the nebula.

 

So, new or old, the DGM NPB will show reds in stars instead of the blue-green color of the Lumicon or TeleVue.

 

There is a slowdown in production recently due to a huge increase in demand and a couple hurried batches that ended up not passing QC.

 

Personally, I found a place for it in my kit along with a Lumicon UHC as they perform differently on different nebulae and sometimes you may want the maximum contrast without the red transmission.

I think the jury is still out on the TeleVue and Astronomik for me.  Like Johnny 5, I need more input (obscure '80s reference).

 

 

Edited September 28, 2020 by Don Pensack

[globular]

It was research and write-ups similar to yours, Don, that persuaded me to choose the DGM NPB as my first nebula (narrow-band) filter.  (Reviews by David Knisely and Phil Harrington clinched it.)
I'm sure I'll accumulate more over time but this seemed a good place to start.
[OIII (line-filter) next I think.... but that's a different thread.]

Edited September 28, 2020 by globular

[jetstream]

We have a very good DGM NPB, in the Heritage 130 the Flaming Star is easily visible among many many others.

[John]

I wish I'd kept my 2 inch DGM NBP reading this 

Obviously it was behaving as it was designed to do.

I'll have to look out for another one ....

[Stardaze]

I've been looking at the DGM NBP today. Think I might try one before a Nebustar, given they're quite a bit cheaper. Are they best purchased directly would you know @John?

I've order a Baader contrast booster filter this morning in hope that the weather improves next week in readiness for Mars..

 

Edited September 30, 2020 by Stardaze

[Stardaze]

On 28/09/2020 at 20:43, globular said:

It was research and write-ups similar to yours, Don, that persuaded me to choose the DGM NPB as my first nebula (narrow-band) filter.  (Reviews by David Knisely and Phil Harrington clinched it.)
I'm sure I'll accumulate more over time but this seemed a good place to start.
[OIII (line-filter) next I think.... but that's a different thread.]

I should have asked where you purchased yours if I may?

[globular]

2 minutes ago, Stardaze said:

I should have asked where you purchased yours if I may?

I got mine from https://okularum.eu/DGM_NPB_filter-2
It took about 5 days to arrive, was well packaged and seems like a good'en.

[John]

2 hours ago, globular said:

I got mine from https://okularum.eu/DGM_NPB_filter-2
It took about 5 days to arrive, was well packaged and seems like a good'en.

That's where I would have suggested. I've never seen the DGM NBP offered by a UK based dealer

[Pixies]

13 hours ago, John said:

I wish I'd kept my 2 inch DGM NBP reading this 

Obviously it was behaving as it was designed to do.

I'll have to look out for another one ....

Hi John,

How would the NBP compare with an Oiii with something like the Veil Nebula?

[Don Pensack]

17 hours ago, Pixies said:

Hi John,

How would the NBP compare with an Oiii with something like the Veil Nebula?

I'm not John, but I can tell you that while the NPB does a good job on the Veil, it is not the equal of a good 2 line O-III filter, which will show you more and with better contrast.

Narrowing the bandwidth in the blue green from 21-22nm to 12nm has a strong effect on contrast.

[John]

1 hour ago, Don Pensack said:

I'm not John, but I can tell you that while the NPB does a good job on the Veil, it is not the equal of a good 2 line O-III filter, which will show you more and with better contrast.

Narrowing the bandwidth in the blue green from 21-22nm to 12nm has a strong effect on contrast.

I am John and I agree with Don !

IMHO nothing is as good on the Veil as a premium quality O-III filter. A UHC helps you to see it when you otherwise might not. A good O-III gives you a target that you can study and explore over multiple sessions.

 

 

[Pixies]

Thanks @John and @Don Pensack

I was looking at getting a UHC and Oiii. Both 2" - so probably one soonish and then the other later. 2 questions, please:

1. Is the NPB more similar to a UHC? And if so, which is better?

2. I know the Oiii is the one-to-have for the Veil, but is the UHC more general-purpose and perhaps get more use in the long term?

 

Sorry - that looks more like 3 questions!

Cheers