What a decent but cheaper nebula filter

[Jemmo]

As the title says I'm after a nebula filter I'm thinking the OIII sounds like the way to God but I don't have a but load of cash. Was a good brand or option. I've put and ad in wanted already for second hand ones

[breammaster]

I ordered one of these yesterday:

http://www.nightskysecrets.com.au/accessories/uhc-1-25-filter.html

[Jemmo]

Awesome cheers mate

[dannat]

O3 is fairly specific -did you have targets in mind?, you might be better with a general nebula filter to start;
something like DGM NPB, or you could just try a GSO/Bintel filter & see what its like

[Jemmo]

Thanks Dan. Just nebulas in general. I want to make m42 a lot more interesting for the Mrs to see and I want to try see rosette nebula too

[Sylvain]

UHC or CLS would be good.
What aperture scope do you have?
Under what sky do you observe (city or out of town)?
Nebula filter linked does not say much at all and the description does not match the filter (filter says nebula, description UHC - could be vastly different filters) ... hard to know what you are getting. Better deals to be had out there IMO.

[gaa_ian]

Hi Sylvain
Your point is taken about the lack of an adequate description for the filter. An oversight in the upgrade to the new site, something which I shall correct. However, I can assure you it is a UHC filter, as per the attached test graph (http://everythingastronomy.com/wp-content/uploads/2013/10/KSON-UHC-Bandpass-Graph.pdf).
The feedback (http://www.iceinspace.com.au/forum/showthread.php?p=1089426#post108942 6) I have had has been very good as well.
Many others have been purchased, especially by IIS members & I believe I have the best value filters in Australia.
Thanks for your opinion, it has prompted me to improve my product listing, much appreciated :thumbsup:

The Kson 1.25" UHC filter page (http://www.nightskysecrets.com.au/accessories/uhc-1-25-filter.html) is now updated.

[CockneyNutjob]

Hi, I bought one of Ian's 1.25" UHC filters and although I have never used one before to judge it against have found it to be excellent!

[Jemmo]

Have ordered one thanks guys I'm guessing it's already on its way

[ab1963]

Hi
I would like to ask if there is a filter that will help with streetlight pollution but would not affect general viewing,this to me is the most confusing subject as the different opinions you read do not shed light,be grateful for any advice so I buy right first time

[mental4astro]

Hi Andrew,

Filters can be very helpful to tease out detail, but there is always a price to pay. As filters work by selectively cutting out all but specific wavelengths of light, this can work to kill of the starlight continuum, and in many instances kill dead the very things we want to see - which is why nebula filters of all types are no good for galaxies*.

But, armed with this knowledge, you can use filters to good effect. From urban skies, the right filter will be very useful for specific objects, like nebulae, as they glow at very specific wavelengths. But there are limits. Light pollution can be greatly reduced and how effectively depends on the filter type. OIII and general purpose nebula filters I find most effective under urban skies, as can UHC type. Hydrogen beta is no good as the overall amount of light pollution is just too overwhelming.

Have a read through the following filter spec article. It is very good at describing the strengths of the many filter types, not just nebula, but also comet and colour filters. It will go a long way to informing you about what filter does what so you can make the best choice for you:

http://www.lumicon.com/store/pg/15-LUMICON-Nebula-Filters.aspx

If you understand for yourself what these filters actually do, it will be better than just having someone rattling off "get this filter or that". It is not confusing, just a little involved - like everything in astro.

Now, expensive brand or inexpensive??? Hard to tell. Some people only ever go with expensive. Others are happy to go with close enough in performance for a better price. But, price can have little to do with it. Many, many different brands get their filters made in one of a handful of companies, so in many instances you are getting the same filter at a range of prices from high to bargain. And it is exactly the same filter!!!! Ian offers some excellent filters in this way! :)

This is not to say that some brands are not justified to be more pricey as these companies can insist on more stringent quality controls and specifications on the filters made for them, and this costs more money to produce. Photo filters can certainly merit this quality control. For visual, I have my doubts, but this does not mean any old thing will do!

AND, there are also some actual manufacturers who because of the facilities they have, have created some very specialized, individual and unique filters that they market under their own house brand or subsidiary. Some of these filters are hybrids of two. Their overall performance is not exactly the same as filters of the individual types, but these hybrids are a good compromise between having two separate filters or just the one. I have one of these hybrid filters, and man, I love it!!! It is the filter I most use. But, if I am chasing a very specific thing, like a tiny, tiny planetary nebula that I am looking for using the 'blinking technique', than I need to use a dedicated OIII filter, not this hybrid. Horses for courses.

* Here I mentioned filters are no good for galaxies. True, but there is one thing that a filter can do with galaxies, and that is help reveal the OIII and H beta regions in the closer galaxies, like in M33. But this requires some aperture grunt and dark skies. Filters won't show the arms or other details in galaxies as galaxies glow in the entire spectrum, not one specific wavelength.

Mental.

[ab1963]

Hi Alexander
Thank you for your time and input,will study the link you have sent and just be patient so I get it right first time hopefully

Best regards
Andrew

[Mokusatsu]

How much have these kinds of filters improved over the years?

I have a couple of early 90s filters, a Lumicon OIII and a Lumicon Deep Sky.

Probably 1991 or 1992 I'd guess.

Lumicon is one of the better brands, and these were "premium" grade for the time (with individual certification of transmission numbers written on the boxes).

They do make images a little fuzzier, stars broaden into asterisks rather than points with either of these filters, but they do make nebulae pop nicely.

The transmission numbers for them are:
OIII: OIII @ 496nm 84%, OIII @ 501nm 96%, H-B @ 486nm 0.1%
Deep Sky: H-B @ 486nm 93%, OIII @ 501nm 93%, OIII @ 496nm 93%, H-A @695nm 91%.

No other transmission numbers (such as specific blocking % at common light pollution wavelengths) are specified.

Now if these were items of electronics, much cheaper new stuff would be technically superior, but I know optics for the most part has not moved as far over the same period so I really don't know!

Questions:

The UHC filter mentioned above, by Ian, would it offer anything I couldn't get with my old Lumicon ones? No point buying something no better than what I already have.

I could buy one of those filter wheels that rotate between five different filters. Assuming one filter would be "nil", I've got my OIII and Deep Sky Lumicon ones, what other filter(s) would be appropriate for deep sky use to occupy the 4th and 5th holes, given that my main instrument is a 200mm f6 Dobsonian?