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Best filters for Nebulae?


CountBorgula

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had my scope out a few times now, and really loving it.  I want to start trying to look for the fainter nebula, e.g. horsehead, california etc, but I had no luck when I tried  on the very clear night we had recently.  Although my skies are good, there is a still slight wash of light pollution. I have heard that there are filters that can pull out nebulae, and was looking for some more advice on these.  I have heard of OIII filters, is that something I should use, would it make Orion and the planetaries (Ring, Snowball etc..) look better?  Busy putting together a Christmas list, so a few of these could definitely go on there!

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Having used quite a few over the years, my feeling is that the priorities should be:

1st - UHC

2nd - O-III

3rd - H-Beta

The first two are both very useful filters for nebulae so many folks own both types. The H-Beta filter is a much more specialised filter that only enhances a handful of objects but it's the tool of chouce for the Horsehead and California Nebulae but see my note below.

Currently I have an O-III which works excellently and a H-Beta through which I've yet to see much to be honest, despite several sessions with it. I think the sort of objects that an H-Beta filter enhances are themselves very challenging objects even with the filter in use.

The O-III has a substantial effect on objects such as the Veil Nebula and the Owl Nebula rendering them clearly visible whereas they may have been barely visible at all without the filter, even with a 12" scope. The UHC type have a similar through perhaps more subtle effect and on a slightly wider range of objects which is why owning both is ideal if possible.

Bear in mind that such filters are no use on galaxies or clusters. Really dark skies are the key "enhancer" for those :smiley:

If you use 2" eyepieces at all you will need 2" filters of course.

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With the usual proviso that there's no substitute for dark skies!

The filter won't make the nebula any brighter, it just cuts out some of the other wavelengths of light.

Example: I was trying to observe the Crab nebula from home the other night.

Not a great night for it anyway, but I thought I'd give it a go.

Found it relatively easily with the 32mm EP, fuzzy grey blob surrounded by a slightly darker area. ;)

Switched to the 24mm with the UHC filter, yep, fuzzy grey blob surrounded by a slightly darker area. :D

It didn't bare much similarity to a crab through the 8" 'scope either.

But don't misunderstand, I was delighted to spot it on such a poor night! 

I'm sure on a better night and at a darker site the difference would have been more noticeable.

Just don't expect any miracles and you won't be disappointed. :)

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i could not believe how much detail M1 showed at SWSP using a uhc...but the skies were dark the app was big the seeing was good and very steady but it wasnt that transparent ...getting all right at once is rare.

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As above but I chose the Baader 10nm OIII first because I was sucked in by its well known capabilities with the Veil and some planetaries which I can now vouch for. What I observed was that after viewing the veil through it I was able in subsequent viewings to pick it out without the filter. Obviously some 'training' had taken place.

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That's a really useful link, Dave, and read this last time you quoted it on a thread about h-beta filters, I think.

For the original post, research each type before spending and also check differences of transmission between manufacturers. The O-III by Baader has a narrower band pass than the SkyWatcher, for example.

I started with the UHC 2 years ago and was the right thing to do. I feel I'm now ready for the O-III and other posters have made the Astronomic sound really tempting! Its far too close to Xmas for comfort, though, and I still haven't decided! Enjoy shopping :)

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As a reward for not buying an ep for a year, I treated myself to an O-iii filter. Wow: saw the Veil for the 1st time - also good on the Owl and Ring. I was buzzing and so impressed, I went mad and ordered a UHC too (both Astronomic 1.25) .. and a cheapo filter wheel. It is too easy to add-to-cart on the TS website! The wheel makes it so easy to swap ep and switch between no filter/moon/Oiii/uhc/TBD on the fly - I have gone 4yrs with a set of colour filters and essentially never bothered really trying them out due to fussing in the dark. Defo recommend Oiii + UHC - very interesting to compare views - though I'm only beginning to really explore what they can do under the sky conditions where I live. Best of luck -N

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I am a massive filter fan and after trying them fairly early on in my stargazing life have gained some reasonable experience. John has it bang on in order of preference as they are not cheap but imho well worth the spend.  

Generally speaking the UHC is the most useful in giving that little bit more, it has proved very good on a number of DSO's and as mentioned if I was only given one choice, this would be the uhc but on a good number the O3 provides the most contrasty results and would indeed be my 2nd filer for nebulae.

The Hb filter is definately a more specialised bit of kit and I have as yet to ge the best out of mine  but I have compared it on M42 and in comparison to the O3 the results were very good. I would love to see a video composite of the 2. 

On a note re: the Horsehead. This is a very difficult object to find. You need very dark skies and perfect conditions otherwise forget it. Also 10" as been mentioned as a minimum aperture although I cant corroborate this. I have been under wonderful dark skies but there was moisture in the air and this was enough to kill it. It is very high on my own "to do" list of DSO's. (Put the flame in there too)

There are of course colour filters and again these have thier uses but these are restricted to planetary for visual. The yellow is excellent for the moon and also Jupiter but the blue is also very good on the latter which really helps teasing out the darker areas of out biggest planet.

Trial and error are a big thing because all our eyes see thing differently but this guide here is very useful too: http://www.cloudynights.com/page/articles/cat/user-reviews/accessories/astronomical-filters/filter-performance-comparisons-r1471#top

I use Baader filters and an astronomic and these seem fine to me but as I have not compared to others I cant really say one way or the other. I do think the HB is the one that is least used would be the one you should spend the most on for results.

HTH

Steve

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I suspect the differences are mostly... subjective? ;)

Courtesy of 365 Astronomy (No personal interest!):

http://www.365astronomy.com/castell-uhc-deepsky-filter-for-125inch-eyepieces-p-1878.html

But I have just re-bought(!) the Baader UHC-S filter for my Video Astronomy.

(Thank you FLO for prompt delivery!) I hope to do semi-quantitative tests? :)

I suppose, at a pinch, with aid of a budget colour filter stacked in front, you

have access to H-Alpha *AND* OIII (H-Beta). For imaging galaxies (other DSO)

I will be using a Neodymium... My main problem is local sodium street lighting!  :p

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My O-III is an Astronomik and my H-Beta is a Lumicon. Both brands have a really excellent reputation but are quite a bit more expensive than most others.

Of the less expensive UHC type filters I've used I thought the Orion (USA) Ultrablock and the Telescope Services (TS) UHC pretty good.

I've owned the Baader O-III and the identical clone branded Celestron and found they darkened the background stars too much for my taste. The Astronomik O-III does not do this to the same extent.

I've not used them but the Skywatcher and Castell UHC and O-III filters seem to get decent feedback on here. Explore Scientific have recently released some competatively priced filters as well so they are probably worth considering.

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I have a castell Oiii and an Astronomik Oiii and the differences are there for sure (mainly in how clean the image is and how neat the star shapes are) in favour of the latter.

that said, I have not yet sold the castell as it is excellent and shows nebulae really well.

personally, I use the Oiii most, then the UHC and then the Hb.

my view is that Oiii reveals things that can otherwise not be seen, UHC enhances things which can be seen and Hb is used on so few objects that it's the least important at first.

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I have the Astronomik UHC and OIII. I previously had a Skywatcher OIII and while it is very good and very reasonably priced, the Astronomik is better. No one can tell you if the Astronomik/Lumicon filters are worth double the cost of the Skywatcher, they certainly don't allow you see twice as much but they are noticeably different/better and I am very happy with the upgrade.

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As a statement of the obvious - UHC filters are designed for emission nebulae? ;)

At most, reflection nebulae will benefit from a (Neodymium) contrast filter.

I am intrigued to try the UHC on fainter DSO's (galaxies) though... 

I suppose it depends which is worse - Loss of light, or light pollution? We will see! :)

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My primary filter is my 2" Lumicon OIII. There are targets that I use it on at every dark sky opportunity and so has been a very worth while investment. As soon as this awful, prolonged period of poor weather clears and we get to the other side of the full moon phase (during which time it is bound to be clear) it will be eagerly put to use again.

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The O3 has a good price also, maybe someone have them and can tell if the are worth buying.http://www.explorescientific.co.uk/en/Optical-accessories/Explore-Scientific-2-O-III-Nebula-Filter.html

85 Euros (with a bit for shipping) is a nice price! I'm trying to read that chart in the screenshot to compare with astronimik's stats. Be great to hear some reviews of this........I might have to jump on this grenade!

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