OIII / filters for visual with 250px?

[Madhatter]

I have been doing some reasearch into filters and have been left a little confused as to how important they are for visual astronomy. For imaging in light poluted skys they are essential-but is the same true for visual?.

I have a 250px dob and observe 90% of the time from fairly light poluted skys (7.5 on stellarium roughly) Would some kind of filter be helpful for me?.

Im confused what the differance is beetwen UHC/OIII/Baader Neodymium Filter, as they all seem do do the same sort of thing. whats the differance?.

Im looking for something that will help cut down the effects of light polution (our street lamps are mostly high pressure sodium-not mercury vapor) and bring out more detail in planets and nebula but without dimming the view too much (idealy not at all but i understand more glass means dimmer views), will i need a couple of different filters for my needs?(dont mind dimmer views if it really makes the differance with nebulas) In my situation what filter would you choose if you could pick just one?.

Sorry for all the questions, but im totaly out of funds and any new extras will have to be saved for. Giving my equipment would some kind of filter be more usefull than a new EP? (just bought a 2x barlow so higher mag will be catered for).

Thanks guys:)

[NGC 1502]

This rather long article is worth a read -

Filter Performance Comparisons - Article

HTH, Ed.

[Madhatter]

Thanks for that artical NGC il go have a read:)

[Mark at Beaufort]

Madhatter I have a 10" Dob as well and personally I prefer my Skywatcher UHC filter. In my opinion if you buy nothing else this would be my preferred filter.

Mark

[RikM]

I have the SW LPR filter. Similar to the Baader Neodymium and it does make a difference to some objects in some areas of the sky but not much in the small scopes I have. I have tried it briefly in the 10" looking at the ring and dumbbell nebulae and it didn't seem to make much of difference there either. Generally, I prefer the unfiltered view.

I have never tried either a UHC or OIII but am very keen to find out how much difference they would make. All filters work by 'dimming' the view, but hopefully they dim the unwanted parts of the spectrum more than they dim your target, making it more apparent in the view.

[Madhatter]

Thanks Mark, that particular filter seems well priced and a good all rounder! have you compared it directly with say the skywatcher OIII?.

[Mark at Beaufort]

Thanks Mark, that particular filter seems well priced and a good all rounder! have you compared it directly with say the skywatcher OIII?.

Yes I bought a Skywatcher O111 and found is too dark for some objects. The views that I have of the Veil etc with the UHC are very, very good. I know that many of the members on SGL have used the O111 filter and give very good reviews. I also know that the Astronomik filter is consider a great product but I don't fancy the expense to find out.

Mark

[Madhatter]

Hi Rik , yes i was just wondering what the differance is beetwen the skywatcher UHC and light polution filters? the UHC is twice the price but both seem to do the same thing?. im not sure the light pollution one would be of much use here though as all lights seem to be HPS not mercury vapor and that seems to be its main light it blocks out.

Ok great cheers mark, the UHC is sounding like it might be the one for me:)

Im currently reading that article, very comprehensive and informative! it would seem its a really close call beetwen the UHC and OIII but i think the UHC may suit me better as i dont want the stars dimmed too much.

[John]

I've used UHC and O-III filters and, when used on certain objects, they make a huge difference. Most of the time I prefer to view unfiltered but for objects like the Owl Nebula and the Veil Nebula these filters can make the difference between seeing something and seeing virtually nothing (even with a 10" scope).

In my view a very worthwhile investment even though not one that is used very often.

[Madhatter]

Hi John , thanks for your imput-thats sealed it im deffinatly getting one of these for my next peice of equipment:D

Anything that helps bring out nebulosity and cuts down LP has got to take priority over more EPs for now.

I just hope the Meade 2x barlow i just ordered isnt junk because i am lacking abit of mag atm.

[John]

Filters are an area where you need to think ahead - 1.25" or 2" ?

You don't want to end up with a lovely 2" wide field eyepiece with no filter to fit it !.

I was observing the Veil Nebula a couple of nights back with my 10" newtonian and my O-III filter and I can tell you that those views were definately worth the cost of the filter alone - a truly lovely object with the filter but virtually invisible without one

[Madhatter]

Thats a really good point there John, at sometime i would deffinatly like to get a nice 2" EP- but i want to wait until i can affored a really decent one that i can look after and keep for a long time-iv only been at this hobby since early april but have always had a interest in the universe and planets around us and can see myself stargazing as long as im able too:)

The vast majority of my EP collection will most likely be high quality 1.25" EPs so i think that for now at least the 1.25 would get the most use, and then when i do finaly save up for a 2" keeper factor in the cost of a 2" filter into the cost.

However- are 2" EPs so nice that once you have one the 1.25s really dont get as much use?.

[John]

....However- are 2" EPs so nice that once you have one the 1.25s really dont get as much use?.

Well it's the field of view that is very nice - it can be a lot larger with a 2" eyepiece which is very nice i) as a "finder" eyepiece and ii) for viewing extended objects like the Veil Nebula, the Andromeda Galaxy etc.

Many DSO's don't need a particularly large field of view though - a 1 degree (true field) is fine and a 1.25" 32mm plossl in a 1200mm focal length scope will deliver a bit more than that

[RikM]

Moonshane will be along in a little while to tell you how good his Castell Oiii filter is

[Madhatter]

Im really very glad i never went for the 12" with no extras now-not just because of size and moving it but because of the amount of extras that are really important!!

[John]

I read somewhere that you need to budget 75% of the cost of your scope for accessories. Sounds a bit modest to me

You can get by fine for a while on the supplied stuff though - it's not a bad idea to do that so that your future buying decisions are made in the light of some personal observing experience.

It always worries me a bit when newcomers produce a shopping list of accessories as long as your arm before even getting the scope !.

[Madhatter]

I guess for some money isnt a problem so it makes no odds (oh how i wish!!)

But that sounds right, personaly i knew i would want a red dot finder as i just dont get on great with finderscopes-though i really should at least try the SW finderscope, i havent ever fitted it:eek: but i find with the RDF i can generaly find things really easy weather permiting with stellarium.

I guess the only real essential with a newt is a cheshire?.

[RikM]

In a way I am so glad I started out with a 60mm scope. It made the views I got in the 6" (second scope) seem fantastic by comparison and so another 2 years down the line, the views I have in the 10" are a similar leap ahead. If I had started with the 10" I would have no frame of reference, so the views would just 'be'.

I reckon I have spent at least 50% on 'accessories' if not more if you count the imaging kit.

[Moonshane]

Moonshane will be along in a little while to tell you how good his Castell Oiii filter is

what the...?? why I ought'a !!!!

just call me Mr Predictable! I was going to as well, but now I'm not. .....OK I can't resist.

Yes, I have the Castell Oiii and UHC filters and also the Baader Neodymium, all 2".

I recommend them all for different reasons.

Like John, I prefer the unfiltered view and believe that the majority of targets are not enhanced by filters unless your light pollution is really bad. Mine is pretty bad but even so, it's unfiltered for me unless it's necessary. You don't generally need a filter for planets or double stars at all - even when LP is terrible.

Here's my summary of use of the filters I have:

Baader Neodymium - this is actually my main moon filter rather than a LP filter, which it also obviously does. Whilst the effect is not so dramatic visually, see http://stargazerslounge.com/imaging-widefield-special-events-comets/147682-not-imager-but.html for the effect of the BNF. It really creates natural colour and substantially more contrast, especially when the moon is 50% illuminated or more. I sometimes use it on Jupiter too and it brings out some detail but there's a colour shift which I am not keen on.

Castell UHC - this is a great value filter and works very well on most appropriate targets. I think this would be a better dark site filter as at home I seem to either want no filter of the Oiii filter and this tends to get left out. I have used it to good effect on the Orion Nebula and others. It creates a much dimmer image (but not as dim as the Oiii) than without the filter.

Castell Oiii - the images is very dim indeed and the stars a distinct green colour. However, this just makes some objects actually visible at home where otherwise I would have no chance. The Veil is a particular object to which this relates. I can detect this even in a 6" scope in relatively high light pollution.

If I had to choose one, for me it would be the Oiii but at £48 delivered approx, it's possible to have both without going OTT completely. The Baader is a great filter but would be the first to go of the three I think, but I do love lunar observing and therefore it's unlikely to go.

Hope this helps and good luck with your choices.

I should add that all these filters add some focus shift and will (IIRC) shift the focus out a little, sometimes quite a bit actually. Also, they do not make objects brighter, just everything else dimmer and therefore the object has more relative contrast.

Finally, no filter works on galaxies (possibly with the exception of the Baader), only dark skies work for those (oh, and aperture - or both!).

Cheers

Shane

[Moonshane]

I have spent about twice on accessories as I have on my two scopes put together (approx) and I got my scopes cheap and most of my accessories used!

[Madhatter]

Thanks for the detailed reviews moonshane:)

Can you aunser why when viewing at home you either want the OIII or none at all? and that the UHC is better from dark sites? is the UHC a kinda "imbetweener"?

My light polution level is beetwen 7 and 8 on stellarium-when its clar to the naked eye the skys dont look that bad, but when overcast the clouds do generaly have a orange tint to them.

[Moonshane]

yes, I'd agree that to some extent the UHC is in between nothing and Oiii in that your eyeball lets all light frequencies in and the Oiii only lets in (I think) two frequencies. The UHC lets in the Oiii and a few more. The article you are reading will tell more.

my LP is Bortle 8 so pretty bad but even then I prefer to use magnification to darken the sky where possible and where the target and seeing allows.

[Madhatter]

Thanks moonshane:) ahhh this is a hard choice but im leaning towards the UHC as i dont like the idea of the stars being a different coulor and really dark, i want it looking as natural as possible with a few benifits.

[Moonshane]

it's a good philosophy and I follow it. BUT if you want to enhance the contrast by only allowing certain frequencies through, this also applies to the light emitted by stars so some change will be inevitable.

[Madhatter]

How differnt is the stars natural coulors through the UHC? do they have a set coulor they change to in the UHC? i would find for instance a purple much more agreeable than green.