Astronomik or Lumicon OIII filter

[alan potts]

Stu,

In all honesty you may as well have asked me that question in Chinese, though I sure you were not directing it at me alone.

Alan.

[alan potts]

To pick up on Johns point, with Orion getting up in the sky eariler every night now it may well be one to try with my dark sky but I am not sure the LX is big enough at 12 inches but it costs nothing to try.

Alan 

[Stu]

UHC filters that have a strong H-Beta band pass have been used to see the Horse Head. The Orion Ultrablock is one example I can think of. It's a rather good UHC-type filter actually and quite a lot less expensive than either the Lumicon or the Astronomik's. David Knisely on "Cloudynights" often recommends the Ultrablock and he really know his filters

I think a dedicated H-Beta with a high band pass transmission % in that line is the most effective on objects like the HH though, and it seems to be an object where you need to give yourself every advantage you can get.

I'm sure your are right re dedicated filter giving best advantage John. I guess if you have a big scope and dark/transparent skies then a UHC may be enough.

Interesting regarding the Ultrablock, I do have a 1.25" one in my case but haven't used it for ages, must give it a go sometime.

Stu

[Stu]

Stu,

In all honesty you may as well have asked me that question in Chinese, though I sure you were not directing it at me alone.

Alan.

Funny :-).

Just trying to educate myself a little more, I'm sure there are plenty of clever people out there who know!!

Stu

[alan potts]

Stu,

This filter lark is new to me and I do find these graphs about them a little confusing to say the least, I always believe that you can make a graph say what you want as they always seem to print the units so small I can't read them. The other point of couse is if the various companies are not all singing from the same song sheet this can onlt further fog the issue.

I would like a filter for things like the orion nebula but am a bit unsure of which UHC to get, I normally throw a bit of money at things I am not to sure of as generally this buys quality, but not always.

Personally I think the cost of these Lumicrons and Astronomik's new make the price of a 16mm Nagler look very reasonable indeed.

Alan

[Joves]

I have the dedicated Hb Astronomik 1.25" filter and all I can say is that you really must need to have it on a pretty darn big scope to see anything through it at all.

[Tiki]

Just for my fuller understanding, what is the impact of the frequencies around 4000 and above 6500/7000 A? The Astronomik has a slightly wider pass around the OIII lines, but is very flat outside this, with other frequencies only kicking in above 8000A. The Lumicon has a tighter pass at OIII, but has a burst of frequencies around 4 to 4500 and then again kicking in from under 7000A. Do these have any visual impact, what do they represent?

The eye is not sensitive to frequencies around 4000A nor above 6500/7000A (according to googled human eye response curve). The Lumicon OIII gives a very dark background when compared to the Lumicon UHC so i'd say that the outlying frequencies have no visual impact and are likely to simply be an artefact of the filter design.

To be able to fully utilize the 'filter curves' you would need to have knowledge of the eye's sensitivity and also of the scattered light which makes up your particular 'dark sky'.

[Stu]

To be able to fully utilize the 'filter curves' you would need to have knowledge of the eye's sensitivity and also of the scattered light which makes up your particular 'dark sky'.

Yep, that's why I asked :-). Thank you for the information.

Cheers,

Stu

[Joves]

They are priced about the same I think - at the high end for filters.

Ok, then I recommend the Astronomik.. Purely because it's the only one I've tried! (So this recommendation should be ignored altogether, please)

[Stu]

Well, rightly or wrongly, I have ordered a Lumicon UHC 2" filter, Christmas present to myself!

Having studied all the curves and read the write ups, I hope this will be useful on a wide range of objects and useable in my 4". Best use I normally get is under very dark skies on holiday each year so dark adaptation should not be a problem with this. It seems to have a similar bandpass to the Astronomik OIII overall, but shifted down so it cuts off sooner after the second OIII line, and includes Hb.

Time will tell how it goes. Will consider again after I've tried it whether I need a dedicated OIII, but it seems there is a fair amount of overlap between different brands UHC vs OIII so perhaps not until I get a bigger scope.

Cheers,

Stu

[Tiki]

... It seems to have a similar bandpass to the Astronomik OIII overall, but shifted down so it cuts off sooner after the second OIII line, and includes Hb.

That's what i thought too.

Dave Knisely wrote an excellent comparitve guide for Lumicon OIII, Hb, UHC and Deep Sky. Under your skies and with your scope you would likely see something very different but the relative help that each filter affords can be estimated. He also concludes that the UHC is the most beneficial overrall by some distance.

In my experience with a 4" frac, UHC and OIII filters, is that the UHC is normally best. I can only ever glimpse the California Nebula with the UHC but i am yet to see any at all with the OIII. The OIII does have an edge with the Veil and NA nebula though.

http://www.prairieastronomyclub.org/resources/by-dave-knisely/filter-performance-comparisons-for-some-common-nebulae/

[Stu]

That's what i thought too.

Dave Knisely wrote an excellent comparitve guide for Lumicon OIII, Hb, UHC and Deep Sky. Under your skies and with your scope you would likely see something very different but the relative help that each filter affords can be estimated. He also concludes that the UHC is the most beneficial overrall by some distance.

In my experience with a 4" frac, UHC and OIII filters, is that the UHC is normally best. I can only ever glimpse the California Nebula with the UHC but i am yet to see any at all with the OIII. The OIII does have an edge with the Veil and NA nebula though.

http://www.prairieastronomyclub.org/resources/by-dave-knisely/filter-performance-comparisons-for-some-common-nebulae/

Yes, thank you for your help with this Tiki. Understanding the filter curves and reading that article helped me to get my head around it more. I think the UHC should be useful for more targets, I do love the Veil though so will have a think about the OIII later depending on the results I get. Are you saying you still see a benefit of OIII over UHC in a 4" on the Veil?

Will report back when I've had some experience with it.

Cheers,

Stu

[alan potts]

I keep thinking of one of these, it will be on my shopping list next time over in Hull..

I hope you enjy it Stu and it gives you plenty of time to let us all know how good it is.

Alan 

[allen g]

I have the Astronomik UNC and Lumicon OIII and use them in my 8" SCT and 4" refractor with same EPs that you have (31 nagler & 21 ethos). both are

top quality filters but I have continuously found that you need dark skies, especially for the OIII, but when you use them in such conditions they make a difference. This past august viewed the Veil under dark skies, with my NP 101, 31 nagler (which gave me 4.5*), and OIII and the entire view was

magnificent.

[Tiki]

.... Are you saying you still see a benefit of OIII over UHC in a 4" on the Veil?

Certainly. There seems to always be more fine detail with the OIII. The fainter blobs between the Eastern and Western Veil show  (when they show at all) in the OIII more often than in the uhc. I think the pros of the UHC definitely make it the 'handier' filter. In general you see more nebulosity with the UHC than the OIII.  If your thread title had been less specific then i would have recommended the uhc.

I bought the OIII and the UHC with the intention of selling one. I still have both and would sell neither. They get too much use.

[Stu]

I have the Astronomik UNC and Lumicon OIII and use them in my 8" SCT and 4" refractor with same EPs that you have (31 nagler & 21 ethos). both are

top quality filters but I have continuously found that you need dark skies, especially for the OIII, but when you use them in such conditions they make a difference. This past august viewed the Veil under dark skies, with my NP 101, 31 nagler (which gave me 4.5*), and OIII and the entire view was

magnificent.

Thanks Allen. That makes sense, I am fully expecting to have to wait to get under dark skies to get the best out if it. Need to plan an observing session somewhere soon.

Stu

[Stu]

Certainly. There seems to always be more fine detail with the OIII. The fainter blobs between the Eastern and Western Veil show (when they show at all) in the OIII more often than in the uhc. I think the pros of the UHC definitely make it the 'handier' filter. In general you see more nebulosity with the UHC than the OIII. If your thread title had been less specific then i would have recommended the uhc.

I bought the OIII and the UHC with the intention of selling one. I still have both and would sell neither. They get too much use.

Thanks Tiki. This thread has been very useful to me, and your input has really helped. I understand far more than I did before, including the amount of overlap between different brands of OIII's and UHC's which is why I didn't know any better in phrasing the thread title.

I will at least be better placed to judge why the filter performs as it does, and to understand future requirements in comparison.

Many thanks all for your input, much appreciated.

Cheers,

Stu

[Stu]

Just to update this, I've now received a Lumicon UHC filter too, to complement the OIII. Looking forward to potentially trying it out tomorrow at a Stargazing Live event. Forecast looks clear at the moment, can't possibly be that lucky can we?

Stu

[25585]

Hi folks,

Found this thread on Bing!

I have both Lumicon OIII & UHC filters in 1.25 inch. They are the early 90s version that came in dark blue translucent boxes with the bandpass % hand written on a label stuck to the box. 

From a visual/aesthetically pleasing POV, I prefer the UHC as it shows the whole scene, so to speak. (Better yet is switching between both).

OIII is best for isolated nebula such as planetaries (M57) or Crab (M1).  Some bright stars still show as in M42 Orion. 

My UHC gives a nicer but less detailed picture sight of M42, showing "mother" & "children" together. 

Nebulae such as the veil are better through an OIII I find, compare looking for faint clouds in the sky, with no aeroplane vapour trails or seagulls. 

Anyone with twin identical eps, as for a bino viewer, could screw each type of filter to one of the eps. As they will be parfocal, switching from one to the other is quick - my own are Vixen 20mm LV eps. 

But for 2 inch eps, I can only afford one filter. The "Goldilocks" choice is hard!

[Stu]

It is definitely a tricky choice. Luckily enough, as mentioned in the previous post I have both in 2" format. I do enjoy them both; as you say they give a different perspective on many objects. The UHC often shows more extent to objects whilst the OIII can show more contrast in the brighter central areas.

With objects like the Veil though, it's OIII all the way!

Out of interest, I recently managed to position a 1.25" filter in the correct place in the light path with my refractor so that it still allowed use with a 2" eyepiece. This involved putting it in front of the barrel of the diagonal. Seemed to work fine.

[John]

If I had to have just one deep sky filter it would probably be the Astronomik O-III. In fact I did go for a couple of years with just that one 2" filter and it did a great job in all the scopes I used it in.

I tend to prefer not to use a filter where I can get decent views of DSOs that way. When I do use a filter I want one thats going to make a really significant impact and the O-III seems to do that.

[GavStar]

I’m in full agreement with John - Astronomik oiii as my only filter if buying new now.

[25585]

The Widescreen Centre sell Astromik filters, including a (more expensive but Lumicon-level priced) 6nM one. 

I do use my 1.25 OIII more than UHC by a margin, so I guess it's the one to go for. 

[alanjgreen]

best price is here

http://www.rothervalleyoptics.co.uk/astronomik-oiii-visual-nebula-filters.html

[Dave In Vermont]

If anyone has an older, pre-Lumicon sale Lumicon OIII or UHC - hang onto them! The new owner(s) of Lumicon has changed the formula, and nobody has done comparitive testing with these. So buying a new Lumicon is an 'act of faith' at this point. The 'used' marketplaces were raided and scoured, but do check periodedly

I wholeheartedly recommend the Astronomik OIII and UHC. These are wonderful filters.

Dave

RESIDENT FILTER-NUT