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Filters for nebula etc.


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Hi.

Is a O(III) filter the best filter generally for viewing Nebula?

I know different filters are suited for different things, just wondering if there is a "general" filter for nebula's, Orion etc?

Also, do they fit over the ep or are they like a barlow where you attach the filter then attach the ep?

Cheers guys.

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Hi,

The most common filter for viewing nebulas is a UHC narrowband filter, most books state that if you only ever buy one filter make it the UHC narrowband filter.

The O-III is good for planetary nebulas and supernova remnants and works best on fast focal-ratio scopes.

As far as i know the filter screws in to the bottom of the eyepiece that you are using.

HTH

Gaz

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I cannot comment on who's UHC filter to buy as i have not used either, but in my opinion all the UHC narrowband nebula filters, filter the same light 24nm, 482nm-506nm so they all perform the same task by reducing what light is filtered, and as they are probably all made in the same chinese factory under different brand names, i would go for the skywatcher which is cheaper.

The UHC narrowband filter also helps with light polluted skies which makes this a good general purpose filter.

I am going for this one here as it costs only £27.49 and will do the job as far as i am aware.

BTW i am new to all this myself and what i have written is based on some of the books that i am reading, but another SGL member with more experience may be able to shed more light on this (shed more light, lol, were talking filters) made me smile anyway. :D

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There is some variation in band between the various UHC and O-III filters. The Baader UHC-S has a wider band pass width than most UHC filters for example, so is more useful with small aperture scopes. The Baader O-III filter has a narrower band pass width than other O-III's so dims the view more and therefore needs larger apertures to be effective. It's worth doing your research carefully with these things.

FWIW I've not used an Orbinar filter but I have owned an eyepiece by them and lets just say you get what you pay for !. A filter is an optical componant as well of course so needs to be reasonable quality if it's not to degrede the view somewhat. I've used the Baader's, Skywatcher's, Telescope Service and Orion Ultrablock filters and optically they were fine.

Edited by John
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Do filters have much effect for general optical viewing or is it mostly just for astrophotography? I really struggle to see most DSOs in my area and would certainly fork out for one of these if it amplified the fainter stuff not visible with the standard eyepiece

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With regard to my previous post about more experienced users able to clarify more on this subject Doc & jahmanson are more clued up than i am and after reading john's post he suggests that a high quality filter will be better than the one i suggested for optical reasons.

@panzer - Filters come in visual, and imaging & photography catergories and filters used in astrophotography are more useful as the cameras CCD can detect more colours than the human eye so is able to use filters to there full extent, with regards to us using filters for visual use i believe that their main benefit is improving contrast and reducing the effect of light pollution so making what is being viewed appear slightly clearer, i have heard that the effects of using filters is not a WoW effect but to some it can make things like nebulas and planets appear more detailed.

I may not be the best qualified on these subject and my knowledge is coming from certain books i have read, but my intention is to put something back into the forum.

HTH

Edited by GazofCorra
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Do filters have much effect for general optical viewing or is it mostly just for astrophotography? I really struggle to see most DSOs in my area and would certainly fork out for one of these if it amplified the fainter stuff not visible with the standard eyepiece

There are some objects where the use of an O-III or a UHC makes the difference between seeing something and seeing nothing. Planetary nebulae such as M97, the Owl nebula and the super nova remnant, the Veil nebula are examples of these.

There are other nebulae where the difference is not so pronounced. Galaxies don't benefit at all from them. The link that Doc provided explains the impact that various filters have on specific objects and is well worth a read.

There are special imaging versions of O-III and UHC filters with the band pass width optimised for CCD's.

I find that I don't use my O-III filter lots but when I do, it's invaluable :D

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John, as i understand an O-III is more suited to fast scopes,as when used on slow scopes of f/10 to f/15 these filters darken the sky so much that users can have difficulty seeing the field of view.

Also do you agree that a UHC narrowband filter is likely to be used more than an O-III?

Gaz

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Sorry for makeing this thread personal to me but with the scope I have (see sig) would I be okay with either the SkyWatcher or the Baader?

It`s an F6 8 inch so sort of middle of the road, could I get away without any of the issues listed above?

Edited by Daz Type-R
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Daz, I have the same scope so either of the filters would be OK with that scope, but i think the UHC narrowband filter would be more useful of the 2 if you are only after 1 filter for now.

I am tempted to buy the Baader UHC-S filter as it is not much more than the SkyWatcher filter but as John said it has a wider band path than most other UHC filters.

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You should check the bandpass of the Baader compared to the Lumicon UHC. I seem to remember that the Baader's pass-band is either a little too wide or that it cuts off relatively more of the OIII lines. Check.

Another good choice is the DMG optics NBP filter. This one is also UHC-like. I think it's only available directly form the manufacturer on eBay. It's said to have a light edge over the Lumicon: it lets in more hydrogen beta and the stars look a little nicer. It's also cheaper than the Lumicon. I have one and rather like it.

Edited by umadog
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There are reviews on cloudy nights (e.g. CN Report: The DGM Optics NPB Nebula Filter - CN Report). Word on the street seems to be that the DGM filter is very slightly better than the Lumicon UHC, but there's not much in it. I've owned both, but not at the same time so it's hard for me to comment on that.

Here is another good article:

Useful Filters for Viewing Deep-Sky Objects - Review

Read around before you choose a filter as they do differ between manufacturers. You can even compare spectrograms and see how they relate to the H beta and OIII lines. To be honest, however, I'm not sure how much one gets out of that without practical experience with the filters themselves.

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Thanks umadog the links you gave were really helpful and considering the cost of the Lumicon compared to the DGM filter, this makes the latter a definate filter to consider as it's performance is highly rated.

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