The perfect eyepiece for nebula hunting?

[Moonshine132435]

I'd like to avail myself of your experience if I may. I have a Skywatcher 6'' Newt (f5) and use a middling site in terms of light pollution. It's some way away from London though I can see the city flown on the horizon. I don't use a Barlow.

My biggest interest is nebula hunting: what do you thing the best single eyepiece in this situation would be, with the caveat that I won't spend more than £120 or so on it?

[John]

I honestly don't think there is one because nebulae vary hugely in size from something like the Veil Nebula which is around 7x larger than the Moons diameter to tiny planetary nebulae which need 200x or more to separate them from stars.

Sorry thats not very conclusive !

A UHC filter would help enhance the contrast of many nebulae though. It's not a "magic bullet" but it does help.

[bingevader]

My not be a conclusive answer John, but it's a good one!

[Joves]

Was thinking the same thing, so I agree, good response, John.

There really is no perfect eyepiece for any particular object, nebulae possibly being the most difficult in this regard. Good that you have identified what objects you are wanting to view, though. Object size plus sky conditions and particular telescope make the combinations vast, if not endless. This is, in part, what makes this hobby so fun.... And expensive!

[jetstream]

You will need a UHC and or an OIII and an eyepiece that works with these in your scope. FLO sells Skywatcher 40mm Aeros that should work well for the Veil, North American neb, M42 etc in your 6" f8, these are 2" EP's with wide views, not sure if your secondary size will fully illuminate it. A 1.25" 40mm plossl will give a narrower view and will work with the filters.

The showcase M27 and M57 will take much more mag and don't necessarily need a filter. How were they with your 12mm NPL?

It will help if you give us what type of nebulae you want to see, realistically there are a few that will be good in your scope from your skies. What is the NELM of your site? They really do need dark skies to see them well.

[alan potts]

I feel the others have said it all, horses for courses .

[Moonshine132435]

Thank you very much for all your responses, there must be a hundred years of astronomy experience in this thread alone. I couldn't say which nebula in particular I'm targetting, as I'm just moving from planetary viewing and have only managed to spot a single nebula so far (Orion, obvs.). However I know that nebulae were always what interested me the most in astronomy, it's just taken a long time for me to build up enough expertise to start looking for them.

The responses are quite positive actually, as there's often a tendency to hope a particular piece of kit is the answer, and I'm just as guilty of this as anyone. In this case there is no one silver bullet, it's just a question of getting out there and spending time behind the eyepiece, seeing what works best each time.

[John]

........ In this case there is no one silver bullet, it's just a question of getting out there and spending time behind the eyepiece, seeing what works best each time.

Thats very true indeed

[rwilkey]

I agree with the comments above as nebulae vary greatly in size.  However, I find the ES82 18mm (2") very good for nebula hunting, priced at £132 at TH but can be got cheaper if you shop around.

[spaceboy]

The only thing I could suggest is see what the limiting magnitude of your scope is and compare that to the limiting magnitude of the nebula visible in your sky then that way you will have a better idea of which nebula are going to shine in your scope as apposed to those that require patience and time to pick out even the most obvious of detail.

I tend to make my eyepiece selections on exit pupil these days rather than magnification, unless I just want a huge field of view but even then exit pupil is the limiting factor. Nebula and galaxies tend to be faint so an exit pupil of 2-4mm is good as this allows your eye plenty of light (even when filtered) but not so much so that the sky is all washed out. I try not to go below 1mm for planetary observing but depending on seeing and transparency this can go down to 0.5-0.6mm.

I agree totally with what John said in that you'd get more benefit from filters. I would though stick with a UHC or LPR filter as although an OIII will work in my 150P it does darken the views quite a lot and you really need good skies to get the best out of it.

[Moonshane]

Good comments above. Do bear in mind that the Orion nebula (M42) is the most impressive nebula of any in the northern hemisphere with the most easily visible detail and wow factor. Most nebulae are faint at best and invisible at worst and won't compare that well with M42. The biggest improvements for faint extended objects like nebulae and galaxies come with the following (in approx the order of importance - my view):

Sky transparency

Dark skies

Aperture

Filters (I would choose Oiii then UHC then LP then Hbeta)

Eyepieces

Personally I would go for the Oiii first as this reveals things (like the Veil) which are invisible otherwise in average conditions with an average sized scope.

Hope this helps.

[YKSE]

I tend to make my eyepiece selections on exit pupil these days rather than magnification, unless I just want a huge field of view but even then exit pupil is the limiting factor.

That's my understanding too, much simpler and more precise than thinking in magnifications.

I agree totally with what John said in that you'd get more benefit from filters. I would though stick with a UHC or LPR filter as although an OIII will work in my 150P it does darken the views quite a lot and you really need good skies to get the best out of it.

 Japp, UHC and OIII are the filters for nebulae.

[swamp thing]

Hi Buddy

When we meet up (surrey observers) you are more than willing to try any of my eyepieces and filters to see which ones you like.

I would agree with Shane's list except I would put filters in front of aperture. Aperture means image scale and most diffuse nebulae are of reasonable size therefore not requiring large aperture. What they need is transparency, and dark skies as these are what provides the contrast we need to observe them.

Filters can really help with contrast too. Making tough to see objects stand out, and even invisible ones visible. They also help 'pull' detail and structure out.

Your 6" scope has sufficient aperture for most of the main diffuse nebulae observable in the night sky. What it needs to see them is dark skies, transparency and perhaps the aid of some filters. 

Larger aperture brings image scale and will show increased detail within the nebulae and in some cases, this can be staggering. Basically what aperture can do is turn a small hazy glow into a great big one revealing any detail on offer. for example, take the veil nebula. In small scopes one can often get the entire loop in the eyepiece. but it is small and pretty featureless.A large scope won't get the whole thing in. In fact in extreme cases only a portion of each of the main segments will fit in any one FOV, but the detail is simply photographic. This is where the wides (eyepieces) come in. The larger apertures really benefit from wide field eyepieces on objects like these. Consequently these wides are also where most of us aperture nuts spend our hard earned cash like I said we're nuts.

Of course you are more than willing to have a butchers through whatever scope I have with me too. This will show you what aperture can and can't do.

[AndyWB]

To be honest, I'd agree - get a filter, and use the rest of your budget driving out to somewhere really dark (note: check the Moon's phase first!) From dark locations, my 5" will show the Veil unfiltered quite happily - but any light pollution wipes it out. Then a filter brings it back! It can be spotted (though not really seen) from near the middle of town with a filter. 

But seriously, somewhere dark it looks great!

[Moonshine132435]

Thanks for all the advice. I'm a bit limited at the moment to my local "dark" site near Dorking. It's not really dark, but miles better than my London back garden. To be honest I found the Orion Nebula last week for the first time (I know, it's massive, how could I never have seen this before!) and spent a good hour just looking at that, so I've got plenty yet to find and explore.

[Dave In Vermont]

Regards a good filter for nebulae, this is an excellent article:

http://www.prairieastronomyclub.org/resources/by-dave-knisely/filter-performance-comparisons-for-some-common-nebulae/

And there are other excellent articles on the site as well:

http://www.prairieastronomyclub.org/?s=Filter

Clear & Dark Skies,

Dave

[LukeSkywatcher]

While i agree with everyone that there is no such thing as a perfect EP for hunting Nebs, and that a filter (UHC or OIII) is needed.............

I have to say that you are on the right track by using Vixen NPL's. In my experience using them they offer amazing contrast and sharpness between objects and the blackness of the night sky. Thats half the battle won. 

The 6mm and 12mm NPL in my opinion are just too tight (high magnification) for hunting down nebs. I use a 30mm NPL for hunting down anything and when i know i'm on target, i slowly increase magnification until i arrive at what feels and looks good for me. 

Another great option for hunting is a 30mm GSO Plossl eyepiece.

If nebulae are your thing (as they are mine), get yourself a UHC filter and/or an OIII filter. A UHC filter works on certain types of nebs and improves the view. An OIII filter will allow you to observe nebs that are otherwise invisible to the naked eye (Veil,Rosette etc).

I have the Skywatcher brand filters (available from FLO) and they work very well for me in my 200mm scope. They fit my budget at the time. There are many different brands out there. 

[Astro_Baby]

I'd caution about filters - I hardly ever use my OIII or UHC - they have very specific applications.  I wonder if with a 6" scope it would make a huge difference and they are relatively expensive items.  For the cost of a UHC and OIII you could buy quite a bit of glass which may make more of a difference to you.

Most nebula are, at least in a smaller scope, pretty faint and fuzzy unless you are under excellent skies.  I couldn't believe how good the Swan Nebula looked from Exmoor a few years ago and in fact it looked better than any astronomical drawing of it I have ever seen.  No filter would have bought out better detail than the application of a tent in a dark sky site.

My advice - get a tent and get away for a weekend somewhere dark.

[Dave In Vermont]

While I understand your point regards putting one's money into good eyepieces, I do, however, believe that good filters can well be a very useful addition to one's arsenal of tools. Not to the exclusion of eyepieces, of course, but alongside. Even simple colour filters can be very helpful in teasing-out fine detail in Jupiter's clouds. And for AP and video-AP, good narrowband filters can make the difference in a good image, and a great one.

To each their own,

Dave

[Moonshine132435]

Thanks for all your views, particularly around filters. I did just go for a 25mm Vixen NPL, but only because they're half price at Astronomia right now, and they're a good upgrade from the stock eyepiece which came with the scope.

[catburglar]

I'd echo some of the previous comments -

moving to a truly dark sky would make the biggest impact, but may not be particularly practical

the right filters will make a big difference from almost all obsering sites

I'd agree with Moonshane- an OIII filter would be my first choice since this will benefit the majority of emission nebulae.

I'd also advise some caution in respect of filters- my current Lumicon OIII is a bit too fierce for my 6inch scope- the views are very dim. I previously used a Castelli OIII filter- which has a slightly broader bandpass- it worked really well and allowed me to see all of the Veil nebula from my suburban site with an 80mm refractor, so it'd work a treat in your scope.

I would be wary of using an eyepiece with a focal length much greater than your 25-30mm in your F5 scope, you'll be getting a 5-6mm exit pupil- unless your skies are quite dark you'll probably find the sky background a bit washed out which reduces the contrast.

First I'd get a Castelli OIII filter, and then I think I'd try one of the Skywatcher Nirvana range of eyepieces. There's a set on Astrobuysell at present. They give nice wide field views - the 16mm would replace your 25mm Plossl (you'll get about the same field of view, but at higher magnification which will improve the visibility) or the 4mm would be a great eyepiece for planetary nebulae which can usually tolerate quite high magnifications, and may also be good for the planets- but you may find you get a bit of ghosting on very bright objects.