Nebular Filter Effectiveness

[Danoz]

Hi Guys,

I'm new here, last year I bought a 8" GSO Cob from Andrews Communication and have recently been getting into it all lost more than when I first bought it. I've only got two eyepieces (25mm and 9mm which came with the scope) and a 2x Barlow.

Recently I've been viewing from my brisbane backyard and have enjoyed seeing soem clusters especially in Scorpious and Sagittarious, but have found the nebulars quite dissappointing (as you'd expect from the city).

I'll soon be travelling in the US and am conisdering buying a nebular (Narrowband) filter (along with a few more eyepieces) to improve observations from my backyard. Can anyone advise me on what improvement I can expect from my 8" Dob, on the lagoon nebular for example which last night was simply a cluster of stars with virtually no nebular?

How marked is the improvement in an 8" scope?

thanks,
Dan

p.s. I'm considering the Orion Ultrablock 1.25" for US$65. any word on this filter, Thanks again

[janoskiss (Steve H)]

there is some obvious improvement on nebulae like the lagoon. but still a pathetic view compared with what you see under dark skies. and you lose the stars in the filter. A good nebula filter is worth having (and can be interesting under dark skies too) though for me it is not an often used observing aid.

[ving (David)]

i have hears that brizzie skies arent too bad

from the outskirts of sydney i can see heaps of nebula fromthe lagoon... you will get better contrast with a filter in place as it will cout out other light.

[mickoking]

First and last words for nebula filters: OIII If you want massive contrast gain on many bright and faint nebulae Oxygen 3 filter is the go.

[mick pinner]

l have found the Baader UHC-S to be very effective although l have not compared it to the O-III.

[Gama]

I dont think there worth the time or effort if living in a suburban area.
I have Meades 2" series 4000 nebula filter and another Japaneese one i purchased about 20 years ago, and used them on my 10" LX200 the 14" RCX and my 22" Newtonian, with only the smallest amount of difference.
Hence not worth the time, but for a dark site i cant comment, as i have never been to one dark enough.
Plus they are useless for imaging with, at least from my experience.
Spend the money on a really good 2" eyepiece around 15mm to 20mm.

[janoskiss (Steve H)]

Gama, you should try a modern narrow band filter. They really do make a difference, and do what they are supposed to well: 90+% transmit light of wavelengths associated with nebulae and efficiently block all other light.

[Gama]

The Meade is only a couple of years old, plus the spectrum and bandwidth are the same with other filters of todays, so there would be no point. Ive used other ones where people swore black and blue they where fantastic, but again when i looked thru it, "BANANAS" !.
Thus i would rather spend it on a better eyepiece.

[janoskiss (Steve H)]

I have the DGM NBP. It cost about $AU100, which would not go far spending it on EPs. I have to admit I use the filter rarely.

[jjjnettie (Jeanette)]

I sold my UHC-s filter, didn't use it enough.
If I knew then what I know now I would have bought the OIII instead.

[RAJAH235]

All filters have their uses, be it a simple Broadband or a H-beta. I use mine on rare occasions but I'm glad that I have them. They do make a difference.
L.

[OneOfOne (Trevor)]

Last night I was involved in a public viewing (about 250 people) in Montrose, an outer suburb of Melbourne. I chose the Swan Nebula to focus on, it appeared much better than at home and decided to put in the OIII filter. The sky darkened considerably (almost jet black), so did the Swan, and the contrast improved markedly. Unfortunately, because of the target audience of "non astronomical" people and about 50% kids 12 and under, I took the filter out otherwise they may not have the patience to study the image and allow the eye to pick out the improved detail. I have not used it much previously, but it definately made a big difference. I will have to try it more often at home. I think the UHC filter may reduce the overall brightness a bit less though as I believe it passes OIII and H-beta? Which means more light will get through in total.

[JoeBlow (Joe)]

I have an Astronomick UHC filter and find that it does make a big difference on some nebula from my suburban skies.

It works particularly well on the lagoon, swan, tarantula and other nebulas. With the lagoon and tarantula I can make out a much larger area of nebula with the UHC and can see more intricate detail in the swan.

[Gama]

All i do to get a darker image and better contrast is to put a higher magnification in.
This i find is better than the nebula filter as there is no drop in signal like it would have with the nebula filter. I recommend about 14 - 16mm Ultra Wide of course, for viewing in a brighter sky. Details of lagoon and trifid come up very nice with this mag.

[RAJAH235]

FWIW. It all depends on your seeing conditions att. It's just that you may not be able to bump up the mag due to those said conditions & this is where the UHC & OIII filters come good. For viewing a wide field object at low/med power they are just fine. They let you see more details. Try a UHC on the Tarantula at med to high mag in good conditions. You'll be amazed at the amount of detail you can see if you take your time at the eyepiece to let your eye/s dark adapt to the 'new view'.
But, everyones eyes are different, so all equipment is personally subjective.
...L.

[ausastronomer (John Bambury)]

Originally Posted by Gama

I dont think there worth the time or effort if living in a suburban area.
I have Meades 2" series 4000 nebula filter and another Japaneese one i purchased about 20 years ago, and used them on my 10" LX200 the 14" RCX and my 22" Newtonian, with only the smallest amount of difference.
Hence not worth the time, but for a dark site i cant comment, as i have never been to one dark enough.
Plus they are useless for imaging with, at least from my experience.
Spend the money on a really good 2" eyepiece around 15mm to 20mm.

Gama,

Owning several top quality filters, including an Astronomiks OIII and UHC and a DGM Optics NPB I just can't come to the same conclusions as you on this topic. These filters offer a tremendous improvement in both small aperture and large aperture scopes "on the right target".

I will add that I usually observe from at worst rural skies and at best very dark skies. However, on the rare occasions I observe DSO's from suburbia, they still show significant improvement on the right target.

CS-John B

[dhumpie]

Hey Dan,

Another Brisbanite And yes our skies are very good. Whereabouts are you? I live close to the uni (about 20 to 25 minutes from the city) and can track down mag 10 galaxies in my 6" from mag 5.4-5.6 skies. Pertaining to your question, yes narrowband filters do help with nebula's (emission and planetary). I previously owned a Lumicon UHC filter and used it heaps from my abovementioned abode. I now own both of DGM Optics NPB and VHT filters and they are great. Nebulosity is greatly enhanced in objects such as M42, the Orion Nebula (you should see its outstretched arms!), Eta Carina Nebula (brilliantly accentuated...wait until you see it with the narrowbands....nice dark lanes), M8, the Lagoon Nebula, M20, the Trifid (where is shows its dark lanes) and M17 (nice feathery structure off the back of the Swan). And planetaries like M57, the Ring Nebula and M27, the Dumbell Nebula look photographic. But I do agree that nothing substitutes for darker skies. Even then this filters help.

Darren

p/s: one of the observing programs you can undertake with such narrowband filters is hunting point source planetary nebula's from close to the city. I have used my filters rather extensively for "blinking" to identify these planetary nebulas (down to my scopes limiting mag of about 13...in the 6" of course not the 10").

[drmorbius (Randall)]

This is an interesting discussion as I've been keen to get either a UHC or OIII filter... still not sure which one to get though...

Anyway, my question is... how much difference does the manufacturer (and hence the price) make to the filter? Is the most expensive really the best value for amateur amateurs like me?

[mickoking]

Last night I was looking at the Lagoon Neb with an OIII filter and I am always amazed how much detail the filter shows, similar to a fairly deep monochromatic image of the Lagoon.

[dhumpie]

Hey Randall,

You have to ask yourself what you want out of the filter. The OIII filter is a great specialist filter for minute detail in planetary nebula's at high power (and it gives superb views of the Veil Nebula). It will also show you different aspects of the same object. However I would recommend a UHC type filter for your 8". Gives you the best balance between brightness and detail. As for brand names, a recent article by Phil Harrington in Astronomy highlights this. There are actually differences between different filters from different companies although I don't think the difference is huge. But if you stick to the well known names like Orion, Lumicon, Astronomiks and DGM Optics you should be fine. I don't know about the Baader ones but I think some members here have tried them (comments to add?).

Hope that helps.

Darren

p/s: by the way try this link: http://www.cloudynights.com/item.php?item_id=63