OIII FILTER

[oldfruit]

Also Russ thanks for the link even though i did not need it.

[russ]

Mark, do you still have the original rack & pinion focuser on your Helios?

[oldfruit]

It does look very similar if not the same but as i`m at work at the moment i am not able to check.

[russ]

I only ask as this comes up quite often. The standard Synta adapters are a right pain in the bottom. The 1.25" adapter looks like a 2"-1.25" adapter but is not and has no thread for 2" filters. Grrrr

So the way round it is to use the 2" adapter i posted in that link with a regular 2"-1.25" adapter into that. You can then use the 2" filter with the new adapter.

All very confusing.

[oldfruit]

I hope this makes sense. My 2 inch adapter sits in my focuser and the 1.25 sits inside the 2 inch.

[russ]

Perfect! Hopefully the 2" adapter has the thread.

[oldfruit]

Fingers crossed. Thanks for the help.

[Astrodread]

I just received my Castel Oiii and UHC filters i have the Skywatcher LPF and im itching to get out and test them all out and compere.

I read alot about people testing all these DSO filters on the Veil nebula, Ring and dumbbell etc but what about star forming regions like M42 (The Orion nebula), Horsehead and flame etc does any one have experience with these filters on those???

Many thanks

Pete (astroDread)

[oldfruit]

I do not have experience with these filters yet but i will be sure to post the results when i do and would be interesting to hear what you find Astrodread.

[Astrodread]

I managed to get out last night with my 10"dob and saw the Veil Nebula for the first time. Ive looked many times before but never seen it with out UHC and Oiii filters YIPPY!!!! Im almost in the center of town so both filters work against the light pollution well. I found the Oiii gave darker background and so was the Nebula but i could see a little more detail. Both west and east regions were visible.

I did have a big fat grin on my face when i saw them. just wondering now, how they look from a darker site with the filters. Wish i had read about using 2" filter with an 1.25" adapter. Fiddling around with these filters at night is delicate work.

Also I found this yesterday posted by AshObservatory. Just what i was looking for.

http://stargazerslounge.com/observing-discussion/78850-filter-performance-comparision-some-common-nebulae.html

[oldfruit]

Sounds like a result and the link you posted is great for someone like myself with no experience using these filters.

To be honest the more i read about it the more i think that if my budget allowed (SANTA:)) i may benefit more from using the O111 filter and the UHC filter as they seem to be suited better to different objects. So having both filters would be an advantage and allow me to get the best visuals on objects that may only be better viewed in one or the other.

I have wanted to see the Veil Nebula for some time and am glad you found it. Just waiting for my turn now.

[Astrodread]

I think your right OldFruit. Ive read that the UHC is good for star forming regions as it lets in H beta light and the Oiii is best for most remnant and Planetary nebulae.

I think i will buy the 2" filters when i have the pennies saved up.

Im thinking about CLS filters as ive read that they help when viewing Galaxies. Does any one know about these filters???

[Andrew*]

CLS is a light pollution filter. It will reduce the background brightness of the sky and enhance the view of any object SLIGHTLY.

Galaxies stand out a little more, but you may not see any more detail.

Unfortunately there is no magic filter for galaxies as there is for the Veil Nebula - a dark sky is the only option.

Andrew

[oldfruit]

Well hopefully as has been publicised today, local authorities may, where practical dim street lighting. So maybe we can all get some better views .

[Astrodread]

I heard about that. isnt it from April??? I hope so. and i think my town is one of the places its happening. Roll on April. and im getting out there now its the clearest night ive seen in a long time. Yippy. Enjoy it if you can.

[jonathan]

Could I just jump in on this discussion quickly and ask a few questions please? I'm planning on buying a 2" diagonal so that I can use a 2" 38mm PanaView as my wide-field eyepiece. The OIII filter sounds very attractive for visual use.

My questions are is a wide-field eyepiece the best one to use for viewing nebulae? Where abouts is the best place to fit a filter? On my first attempt to fit a moon filter the only place I could actually find a screw thread was on the end of the star diagonal (the end that fitted into the telescope), does it make any difference where the filter is fitted, and did I fit it to the correct place? Sorry if I've asked this question before!

[sixela]

Hi,

I am interested in looking at more planetary nebula and nebula in general and have read that an OIII filter can help, but when i have read info on the sites that sell them they have said that they are really only any use on telescopes of 200mm aperture or more.

I've used a much more aggressive H-beta with the naked eye (aperture 7mm).

So take it with a pinch of salt.

What is true is that often you won't be using a filter like that on faint emission nebulae with exit pupils under 3-4mm (to get the exit pupil divide the eyepiece focal length with the f/ratio of the scope).

But some planetaries have high surface brightness but are small, and you'll possibly also beat that rule of thumb.

One caveat: if you don't have one, you might consider using a more general UHC filter first (preferably a really good one, like the Omega Optical NPB or the Lumicon UHC).

[Moonshane]

hi jonathan

Oiii and UHC filters are generally best at lower powers as a larger exit pupil suits them better on the whole.

which EP you use depends on the size of the target really eg the Orion Nebula is big and the Veil nebula is HUGE but most Planetary Nebulae are small and you need some magnification to see them well.

in terms of where to fit, I think the answer is as close as you can get to the optics (i.e. eyepiece) but still being convenient. a lot of people use the diagonal as you do, or if you use an extension piece this is good too as it prevents changing the filter with each EP - don't forget it's in though or you'll be scratching your head thinking what's wrong with my scope???

others use the filters on the EP and just change it each time - riskier in the cold and dark.

[sixela]

My questions are is a wide-field eyepiece the best one to use for viewing nebulae?

Depends on the nebula, the focal length of the eyepiece and the scope. Wide field eyepieces are useful to keep the exit pupil moderately low (to magnify nebulae more to see more details in them) while you keep a wide true field of view (to frame the object better).

But it you're observing a tiny planetary nebula, a wide field eyepiece doesn't help you much --except if you're looking for context and aesthetics--. I do like the aesthetics of the Eskimo Nebula floating in a sea of stars seen through a 13mm Ethos barlowed to absurdly high powers, but I still use a narrow field 5mm eyepiece to actually observe it.