Nebula Filter, which one?

[warpout]

Looking to invest in a decent nebula filter, around £50, but would not mind paying a little extra for a quality filter(cheaper if possible). Having read reviews, each filter seems to have their plus and minus points. What would you recommend for a first nebula filter. All suggestions considred. Thanks.

[John]

Depends on what scope you will be using to some extent but usually a UHC type filter is found to be the most versatile although the O-III type makes more of an impact on certain nebulae.

The Castell filters seem to have a good reputation for their price and the Explore Scientific ones seem decent as well.

Are you going for a 1.25" or 2" filter ?

[Ben the Ignorant]

I've had impeccable results with Astronomik's broadband UHC-E filter. Used it on 80mm f/6, 80mm f/7.5, 127mm f/10, 150mm f/5 and 300mm f/5 scopes with superbly clean definition, and good extension of nebulas. Improves many galaxies, and comets, too.

Astronomik filters are expensive in general but that one is not, luckily:

http://www.teleskop-express.de/shop/product_info.php/info/p328_Astronomik-ASUHCE1---UHC-E-Filter-fuer-1-25-Zoll-Gewinde.html

[furrysocks2]

Can't answer, but reminded me of a recent read: http://www.prairieastronomyclub.org/useful-filters-for-viewing-deep-sky-objects/ - this may or may not be useful to you.

[Size9Hex]

My UHC filter sees a lot more use than my Oiii. It shows larger areas of nebulosity than the Oiii. Not to say that the Oiii is worse though - I find it shows a darker view with less nebulosity, but often also reveals dark detail that's not apparent in the UHC. If I could choose just one though, it'd be the UHC. I observe from a reasonably dark location, and some of the threads on here have made me wonder if an Oiii might be preferable from a more heavily light polluted site.

I wasted a bit of money by buying a 1.25" filter first and then later buying a 2" wide field eyepiece which needed a 2" filter. Not sure what kit you use but worth considering. Nebulae absolutely love low power wide field 2" eyepieces!

Oh and mine are Skywatcher which I think are good but not brilliant. Good enough that I'm not in any huge rush to replace them though.

[laudropb]

If your telescope is 150 mm aperture or smaller, then the UHC filter will be the better choice. I used the Skywatcher version for a couple of years and found it very good.

[warpout]

A bit more info to my earlier question. My 'scope is a Skywatcher 8" refractor and I use 1.25" eye pieces. It appears that upgrading to 2" ep's wouldn't be a bad idea. Also, there is a fair amount of light pollution where I live.

[Size9Hex]

I'd feel bad if you bought a 2" eyepiece purely off the back of my comment when you were asking for filter advice. I should say that I only use one 2" EP (a low power wide angle 24mm) whereas all my others are mid to high power wide angle 1.25" - and I'm very happy with them. I use the bigger brother 10" version of your scope. From my somewhat light polluted back garden, the 24mm doesn't get a huge amount of use - I find a slightly higher power pushes through the light pollution more effectively (i.e. it makes the sky darker which looks nicer and makes the object bigger which make it easier to see). The 24mm gets a lot more use at a dark site however. It's not the fact it's 2" that made me choose it, but the fact it's low power and wide angle (with the 2" simply being needed in order to provide low power and wide angle on the same single eyepiece - 1.25" can't deliver both). If a 1.25" could have given the field of view and low power I wanted, I'd have gone for it.

Hope that clarifies. Sorry to derail this one.

[rockystar]

1 hour ago, Size9Hex said:

I should say that I only use one 2" EP (a low power wide angle 24mm)

same, 1 2", the rest 1.25". I suppose this does make choosing which size filter to buy . Mine are 1.25" and only occasionally do I think it'd be nice to have a 2" filter.

[alanjgreen]

Warpout,

as said above, if this is your first filter, then UHC makes the better choice. I use mine on more objects than my O3 for example.

i started out with the skywatcher UHC from FLO and it served me well for a couple of years, it improved many nebula noticeably.

i have now moved on to the much more expensive astronomik version, which is noticeably better than the skywatcher.

but you get what you pay for with filters seems to be the rule, there don't seem to be any shortcuts.

if your scope uses a star diagonal, then also consider that the filter can be screwed into that meaning that you can change eyepieces with the filter still in place - therefore buying a size to match the star diagonal may make sense - check if your diagonal has a filter thread on the inside edge of the end that goes into the scope?

Alan

[JOC]

Newbie question - given that Nebulas are already only dim 'whisps' of light in the sky why does adding a filter against a black background improve their viewing?  I would have thought that there is already so little light coming from them that any more obstruction of any of the light arriving would just service to diminish what you see?  If a filter would improve my ability to see them I'd happily buy one.

[alanjgreen]

9 minutes ago, JOC said:

Newbie question - given that Nebulas are already only dim 'whisps' of light in the sky why does adding a filter against a black background improve their viewing?

 

Follow the link -

The Use of Astronomical Filters

I quote "

First of all, let's start with the question of why one uses a filter at all. Simply put, a filter can greatly enhance the human eye's perception of small details on solar system and deep sky objects. There are those amateur observers who maintain that they never use filters and that one doesn't need them. To this argument, I have only this to say; no pair of human eyes is perfect. If a filter helps you get better use out of yours, then use them. Judicious use of photo-visual filters can greatly enhance an observing session.

 

Filters work by blocking a specific part of the color spectrum, thus significantly enhancing the remaining wavelengths. Colored filters work by absorption/transmission, and instantly tell you which part of the spectrum they are reflecting, and therefore transmitting. The so-called light-pollution reduction and nebulae filters are very selective in the wavelengths they transmit. For these it is best to refer to the manufacturer's specifications on a given filter.

"

All I can add personally is that they DO work, I've seen it with my own eyes (with reference to UHC & O3 especially)

- I would not advise anyone to purchase the colored filters, they seem to be less giving !

 

 

[LukeSkywatcher]

I have both a UHC and an OIII filter (Skywatcher). They both have a use in my 8" SCT. The UHC gets more use (there are more objects to use it on). 

[JOC]

That's an interesting PDF thank you. 

Maybe the author will do a cut and paste one day and line up the colours being discussed with their respective texts as I think they are a little muddled at the moment ;-)

[YKSE]

1 hour ago, JOC said:

Newbie question - given that Nebulas are already only dim 'whisps' of light in the sky why does adding a filter against a black background improve their viewing?  I would have thought that there is already so little light coming from them that any more obstruction of any of the light arriving would just service to diminish what you see?  If a filter would improve my ability to see them I'd happily buy one.

Typically, nebulas are in very narrow light spectrums (H-beta in 486nm, OIII in 496nm and 501nm), while the background sky glow are in all visual spectrum from 400nm to 650nm.

This is a typical UHC filter transmission spectrum:

It cuts most of light outside the nebula spectrum, so the light reachs our eyes contains higher percentage light from nebula, therefore better constrast for easier seen, despite there's actually a little ransmission loss (not 100% in the graph) of the nebula light.

As other's have already commented, these nebula filters (UHC, OIII and H-beta) works only with Nebulas, not on stars, globulas or galaxies, since those have continuous light spectrum, a filter wil only reduce the transmission, withouh enhancing the contrast.

PS. No rule without exception, some galaxies, e.g. Seyfert II has very strong nuclei which emits lights mostly in UHC's spectrum, so a UHC filter will be helpful to see the nuclei of these galaxies, the galaxy itself might be lost with the filter though .

[JOC]

YKSE - I'm a visual person and that graph works much better for me.  It's like the graphs you get from spectrometers.  It does make sense if the filter is used to eliminate background frequencies and allow those you want to pass-through.  It's like reading emission spectra from atomic shell shifts in spectroscopy against a black background where these minute frequency changes emitted by electronic shifts would be obliterated by any white light present; where the same light frequencies being emitted by daylight would obliterate those being generated by the sample being studied.  I am just surprised that the blackness of the night sky still puts out sufficient background frequencies to make their cancellation by a filter worthwhile.  The 'black' sky obviously isn't so 'black'.

[John]

The UHC and O-III filters really do work and work well on objects which emit the wavebands that they admit. For visual you want filters with high transmission rates in their selected band widths, over 90% and 95% or more for preference.

I have UHC (Omega DGM NBP gilter) O-III (Lumicon) filters in the 2" size and an H-Beta (Explore Scientific) in the 1.25" size. The latter is specifically for a much more limited group of target objects and would be somewhat further down your "wants" list I think.

In my case I find the O-III filter gets more use than the UHC and I think that is because I prefer unfiltered views usually so I'll use a filter where it makes an overwhelming difference to the contrast of the target object and the O-III is the one that does that. I do also enjoy the more subtle effects of the UHC type but if I had just one filter it would be and O-III and in fact for a few years an Astronomik O-III was my only deep sky filter.

The difference that the O-III filter makes on some objects (and they are real showcases such as the Veil complex in Cygnus) is really outstanding and it can transform a portion of the Veil from practically invisible to "wow !!! it looks a bit like the images", it really can

I've also found that O-III filters work just fine in smaller apertures - my scopes go down to 4" and I often use the O-III to view with the smaller ones.

 

[alanjgreen]

Here is another link that I found useful in the past.

This site is very helpful: http://www.prairieastronomyclub.org/resources/by-dave-knisely/filter-performance-comparisons-for-some-common-nebulae/

it scores filter types 1-5 per sky object

His RECOMMENDATION RANKING SUMMARY is (added color to separate them on the eye)

 

UHC best on 41 nebulae, close second best on 47 nebulae.

TOTAL 1st and 2nd RECOMMENDATIONS for UHC: 88 objects.

 

 

OIII best on 34 nebulae (biased by the inclusion of some planetary nebulae),

close second best on 22 nebulae.  *NOT* recommended on 6 nebulae.

TOTAL 1st and 2nd RECOMMENDATIONS for OIII: 56 objects.

 

 

H-BETA best on 16 nebulae, second best on 2 nebulae.

*NOT* recommended on 39 nebulae!

TOTAL 1st and 2nd RECOMMENDATIONS for H-Beta: 18 objects.

 

 

DEEP-SKY best on 7 nebulae, second best on 3 nebulae.

*Provided at least some slight improvement for *all* nebulae surveyed.

TOTAL 1st and 2nd RECOMMENDATIONS for DEEP-SKY: 10 objects.

[jjosefsen]

On 01/11/2017 at 23:05, laudropb said:

If your telescope is 150 mm aperture or smaller, then the UHC filter will be the better choice. I used the Skywatcher version for a couple of years and found it very good.

This is what I use on my explorer 150p, and it worked well on the Orion Nebula.

I read from multiple sources that it was one of the better mid tier priced filters.

[N3ptune]

A person from the forum recommended to me these NPB filters (narrow pass band), similar to UHC.  They are a great deal $190 + shipping for 1x 2" and 1x 1.25", made in the USA.

http://www.npbfilters.com/

I wanted to have the 2 dimensions because:

- A large nebula can benefit from a low power 2 inches eyepiece with large exit pupil, the Veil for instance. For that it's the 2" filter

- And a smaller nebula will require higher magnification, that's where the 1.25" filter comes in. (I use both filters, they greatly enhance many nebulae, it's impressive)

The total price I paid with shipping from US to Canada was around 260$ CAD (shipping was about 20$, everything went well and fast).  Now I don't need anything else for DSO's ,it's pretty much complete for me now.

 

[SloMoe]

 

Joc, in the your price range there's not a lot out there and there are a lot of manufactures claim UHC but are not true UHC's.

Lumicon, DGM optics, Thousand Oaks, all three quality filter manufactures.

This is a very popular topic on many astronomy forums.

For a quality piece of glass that will help you you're going to pay almost $100. for each.

A narrow band filter might be better, are there any astronomy clubs near you or star parties that you could attend and have the opportunity to view thru some of these filters.

Narrow band and O-III filters contrast the light better for one nebula than the other will.

There isn't one do it all filter when it comes to nebulae.

Do more research before you purchase your first, 

Thousand Oaks has LP-1 which is a true UHC, LP-2 is the visual narrowband, & LP-3 is the tight O-III wave band. all very good

Lumicon, Deepsky, UHC & O-III -all very good

DGM Optics NPS, VHT, & O-III are Highest rated.

But, All of our eye's will receive light differently and all results vary, to make the best choice you're going to have to look for yourself.

To answer your second question, with your scope and 1.25 eyepieces go with 1.25 glass, lot less hassle than swapping filters from the eyepiece than pulling the visual back and changing a filter.

With a larger aperture, 8" and up then build your 2" visual pieces. 

 

[Dave In Vermont]

Regards the OIII filters available out there, the Astronomik OIII gets the best reviews when used visually. This as they let in enough wavelengths to not dim the target and, thereby, give excellent views to come through. I can personally verify this opinion - having both a Baader and an Astronomik OIII.

One nugget of advice: Don't let the price of these act as a guide. Getting a 'Brand-X' UHC or OIII is no bargain - if it's going to sit in a dark-drawer and get no use. These little hunks of glass aren't cheap.

Enjoy -

Dave

[John]

56 minutes ago, Dave In Vermont said:

Regards the OIII filters available out there, the Astronomik OIII gets the best reviews when used visually. This as they let in enough wavelengths to not dim the target and, thereby, give excellent views to come through. I can personally verify this opinion - having both a Baader and an Astronomik OIII.

One nugget of advice: Don't let the price of these act as a guide. Getting a 'Brand-X' UHC or OIII is no bargain - if it's going to sit in a dark-drawer and get no use. These little hunks of glass aren't cheap.

Enjoy -

Dave

I had the Astronomik O-III for a couple of years and it was a great filter. Interestingly, the filter "guru" David Knisely does not rate it that highly due to it's generous band pass width. I liked it a lot just because of that - it was very effective in a wide aperture range of scopes.

Maybe there is a degree of personal taste involved in deciding which filter suits best ?

 

[Dave In Vermont]

On 1/19/2017 at 04:15, John said:

I had the Astronomik O-III for a couple of years and it was a great filter. Interestingly, the filter "guru" David Knisely does not rate it that highly due to it's generous band pass width. I liked it a lot just because of that - it was very effective in a wide aperture range of scopes.

Maybe there is a degree of personal taste involved in deciding which filter suits best ?

 

"...personal taste"? Surely you jest! Oh course 'personal taste' plays a role in this business!

The Baader OIII simply results in less to see, due to it's tighter band-pass. This may be just what one may desire for AP and longer exposures. But for visual use, I'd think the viewer would want to elicit a brighter and, thus, more interesting view at the eyepiece.

And that's why I'm now saddled with TWO OIII-Filters from TWO highly respected suppliers of these rather costly little pieces-o-glass.

No offense intended to David, another 'Filter-Nut'-

Dave

[SloMoe]

Well, after a bit of surfing I found this; http://www.astronomy.com/~/media/import/files/pdf/8/c/7/0805_nebula_filters.pdf

might help.