Filters - Help to settle a disagreement :)

[Davekyn (David)]

My good friend & I seem unable to agree on which filter is best used for what. I am a little bewildered that my friend relies heavily on a OIII filter for Nebula's other than Planetary Ones.

I have owned both a UHC and OIII and found the UHC to be far superior when viewing most Nebula's.

I understand that not all nebulas are the same, and will do better with filters designed more specific to the light coming from that target.
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My friend claims that it was here at iceinspace that he was informed that an OIII filter is best use to view Nebulars. I was quick to explain out of the UHC & OIII, that I found the UHC gave much much better results on targets like M42 Orion as well as Carina Nebular.

In fact, I was quite astonished at just how much more he was missing out, when using a OIII filter on the Carina Nebular after looking at it myself in his 12" Dobsonian. I too once owned a 12" Dob and when Using a UHC on Carina, I could see HEAPS more detail.

I find that the OIII filter cuts out WAY too much light on such targets I have mentioned. In fact I told him, it was at iceinspace that I was told a OIII filter was better suited to planetary nebulas.
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He pulls out his OIII filter and points to the word "Nebular" on it. LOL ...
All I can say ... is the OIII is all he owns.
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So ... I beg the question ...
Surely he would do much better to view M42 and Carina NGC 3372 bla bla bla with a UHC any day over his current recommendation of a OIII???

Thanks In Advance ...

[Davekyn (David)]

Such and such views and no responses? I'm not looking for an argument guys.
I guess I do go on a bit.

Allow me to simplify:

If you own both a UHC & OIII filter which one do you use most.

I know the pace can be a bit slow here and people like to redirect when a topic has already been discussed ... Therefore:

http://www.iceinspace.com.au/forum/showthread.php?t=292
Hey Buddy ... not sure who told you What ... about the OIII filter ...
But you can clearly see, given the response in the above link there, that the UHC is the better all round performer.

Just to be sure on that ... let's see what others have to say at Stary Night:
http://stargazerslounge.com/topic/12...r-oiii-filter/
&
http://stargazerslounge.com/topic/108145-oiii-vs-uhc/

UHC again comes out the most preferred weapon of choice yet again, with the OIII cutting out too much light on NON emission nebulars.

Again ... I was advised that the OIII is best suited to planetary Nebs ... Personal experience from someone who did drag their 12" dob out to a dark site compulsively over and over again ... I rarely used my OIII filter when I had my UHC on hand to use. I was so disappointed with how much light it cut out, I probably missed its benefit on targets it did work with, simply because I would not even waste the energy to try ... given the much more impressive results of the UHC filter.

Don't get me wrong ... it has it's use ... but in general ... anything less that a 12" dob and the comparisons only get worse for the OIII filter. I noted that response at one of the above links and have to entirely agree!

I intend to follow your advise and get a "small" loan and get myself a 10" dobsoinan ... but I sure as hell won't be getting a OIII filter for that sized scope as I remember well, the bitter disappointment having spent $80.00 at bintel for the OIII when compared to the UHC. But then again ... I was tripping over a lot of me gear, so in the end it fitted in well with my other rarely used items.

So Buddy ... I have not even mentioned cloudy nights yet. I'm betting the overall response will have "also" have the UHC filter as the Best all round performer. Just consider that OIII for those specialized targets it's intended for ...

I bet you $50.00 worth of Gold on World Of Tanks, that you will understand why it is that I have written like so ... and that you will see a massive improvement in your 12" dob with the UHC whence compared to "most" of nebula's you have looked at thus far! Think about it ... If I am wrong, you can buy yourself a new premium tank or upgrade some of your crews.

PS ... not sure who told you or where you read that these filters "improve" the view of Galaxies ... BUT that information borders on insulting. I'll bet you enough gold to buy you a Level 10 tank ... if you can prove this out in the field.
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The Best Way to find out is BUY a UHC filter ... then I know you will be annoyed with your OIII filter ... especially given the advice you received.

What store did you buy that from again?

PS ... glad I check out some links and pricked my own memory on this topic ... as with a 10" scope, I consider such a filter almost useless for my general observations.

[Davekyn (David)]

Also ... for the love of god ... if you do get a new mirror ... Please do NOT store it in your shed.

I realize we had a bit of moisture in the air with a few clouds about, but I swear on my mothers grave, that a lot can be done to further improve your views due to the current condition of your scope.

Definitely invest in a shroud or make one up and use a lightweight closed cell foam mat around the top to help cut out dew and fast blowing particles.

The amount of dust, hair and fine scratches I saw on both mirrors makes using filters pointless to begin with as the amount of light coming in from some of those galaxies was WAY to dim compared to a well looked after 12" dob. I would also not use a micro fibre cloth like the one you had as they will infact leave scratches themselves.

I ended up using a good lens brush with a bulb blower to clean mine ... I never knew any of this stuff and in fact did more damage and than good when I first started out ... but the biggest thing for guys like us ... whom have sheds with dust, moisture and wind that get in, is to NEVER EVER store our astronomy gear in them! EVER ...

I don't care what my wife says ... The scope always makes its way into my bedroom cupboard if it can fit ... I think the 10" tube choice will be my next best choice for such a tactic. If she does not like it, then she will have to go. You know how it is.

Anyways mate ... Lets go star Gazing again? I manage to wire up my old red dot finder, so wont have to aim my little refactor like a cannon.

The things some of us have to do. $$$

[sgazer (Lee)]

An OIII filter will only work well on nebula which transmit strongly in the OIII band, ie one which mostly contains doubley ionised Oxygen, such as the Veil nebula. According to the link below;

http://www.astrobuysell.com/paul/filters.htm

there are lots of nebula strong in OIII, particularly panetary nebula and as it's a line filter, it will make the background very dark.

However, you are missing out on all the other bands, such as the very common Ha. A UHC filter will allow you to see all the major bands, whilst blocking out unwanted light, but it won't block out as much as the OIII would as its pass bands are wider.

That's why narrow band imagers using line filters get excellent images, as they make the background so dark, but multiple filters are combined in the image processing, so you can capture all the emission bands, of course you can't do this with your eyeball, so you either need to capture all of them using a UHC and risk a brighter back ground or see one emission at once using an OIII or Ha filter, with a darker back ground.

The filters are so narrow though, that they are generally best with large aperture scopes for visual. (Imaging is another matter).

Their performance will also depend on whether you have good or bad light pollution in the first place.

Regarding using a filter on galaxies, I don't think it's as clear cut as you say in a light polluted area anyway. I think a UHC filter will still darken the background light pollution and allow most of the light from the stars to pass through, making it appear better.

[Paddy (Patrick)]

Interesting thread Dave, in part because I feel like I'm hearing one half of a conversation.

Anyway, for me I tend to use the UHC more than OIII for most emission nebulae and both for planetaries. If I was going to have only one, it would be UHC I suspect.

I don't observe from light polluted locations so can't comment on use for galaxies under those circumstances. I sometimes use UHC filter for bright spirals to show up star burst regions, but would otherwise leave a filter out for galaxies.

[Davekyn (David)]

To clarify ... For observational Astronomy ... in a dark site. + They really need to be more specific when selling those OIII filters for Nebulars, but hey ... easy to take the $80.00

Thanks for the insight guys. Yep Yep ... you might get the other half of the story if my mate decides to jump on in. I'm well prepared for a flaming.

Sgazer ... nothing I say is ever clear ... Light Pollution sucks full stop! I do however get what your pointing towards; or at least I think I do.

Point taken on images, however for observational purposes in this case ... the OIII filter is next to useless on most targets (specified "nebular") commonly viewed in small telescopes with the one eye ball ... imo That I am being clear on. Or perhaps better said, "not for the causal user" as it will surely disappoint. I find the wording NEBULAR imprinted on the side of filter itself, somewhat misleading ... as are all things in the retail business. When he acquires a UHC or when I show him ... he will get the point ... Indeed! At least the guys at Bintel did ask me how big my scope was when I even bought a UHC ... that was nice of them!

I did try it on the crab nebua from a dark site and thought maybe I was having a case of creative thinking going on ... not sure. I do believe I was able to pull out some lines I may otherwise could not see without using it. It was a long time ago and as I am hitting on, out of many observations, I rarely got to view many targets that actually utilized it, therefore making the UHC a much more versatile piece of equipment.

As mentioned so far it's just me blowing my horn ... Or simply try the above links where I have already found it discussed ... where the opinions of others may better clarify.

As for my friends half of the story ... no comment can be given until he actually posses a UHC, and then that is when I get a New Premium tank for picking a clear winner and giving him the advice he should of first received.

I was further confused at his mention "someone told me" that the OIII was good for the flame nebular and Horse head ... again I struggle with this ... knowing just how faint such a target it. There are posts on how to better prepare in ordered to see the horse head nebular with a 12" bob ... Have a spotless mirror, use shrouds, wind protection, dew protection, pick and absolute dark site, go in good conditions and on and on ... and then someone comes up with the idea to throw a OIII over the eye piece for observational astronomy. Nar ... surely not?

[Giorgio]

What happened Dave?

I thought we have had a good time the other night, but from your writing it doesn't sound like that.
Although I'm not anymore the noob, I never made mistery I'm way still on the learning curve in all about stargazing. If I knew you have religious like believes about filters, etc.. I would have restraint my self from pronouncing such a blasphemy and end up publically processed for my sins.

I take good care of my gear and you know better. Next time (which is not going to happen), please give me at least a few days, instead than few hours, to ensure my second hand dob will look like new for such an improvised stargazing session. after many months of not using it. I would have even replaced the secondary with the almost new I already bought.

Sadly my wife, who I value more than my gear, doesn't agree with storing a 12" dob inside our house. Also, having it in the shed make it easy to move it in the backyard and more safe from kids pets and the like.
I actually, if I were you, would keep it out of reach of someone who may experimenting with a 10" dob aerodynamics properties, as it happened with your high tech PC.

Rest sure I will not disappoint your ecumenical stargazing believes any more in the future. Don't expect further comments from me.

[Davekyn (David)]

Jesus mate ... I thought you knew me better than that. Never meant to imply it was not a good night. I quite enjoy getting out. You've miss read completely. We both agreed given how adamant you were on the topic, that I'd make a post on it ... Sigh.

It's just a post about UHC Vs OIII , not a character assessment. No worries Giorgio. My apologies.

PS ... I'll unshackle the wife; given how you have touched me so.
Kidding Mate!

Happy stargazing.