UHC filters

[petermarknimmo]

Having seen the ring nebula last night, it has renewed my interest for purchasing a UHC filter, however I have heard that smaller scopes (mine is 4 1/2 inch arperture) can struggle with this filter due to its light transmission. Is this true?

And whilst I'm at it, would anyone be able to confirm that the OIII filter is completely out of the question for my telescope?

[DOBBY]

Yes &.. Yes

[John]

The Baader UHC-S is designed for smaller aperture scopes. I used one successfully with 100mm and 80mm scopes to show me the Veil Nebula so I can confirm that it works rather well. I have also used an Orion Ultrablock successfully in a 4" scope - the Ultrablock is a UHC type filter.

I'd agree that most O-III filters need apertures of > 6" to work well though. The Baader O-III has a particularly narrow pass bandwidth so needs 8" or more in my view.

[Uhwaz]

maybe http://www.teleskop-express.de/shop/product_info.php/info/p511_Baader-Skyglow-Neodymium-2----more-contrast-on-Moon-Planets.html

could work well ?

[rwilkey]

I agree with John, I have the UHC-S filter and it works well in smaller apertures, has greater light transmission so more classed as a broadband filter.

Edit: the Baader Neodynium filter does not perform the same role in my opinion, not suitable for nebulae.

[Uhwaz]

Taken from the website

The Skyglow's filter curve:

the curve progression is similar selective like a nebula filter but the Skyglow has more broad band effect.

Hence why i thought it could be good for smaller scopes.

I got it last week just didnt have chance to try it out yet, seen loads ppl here use it as good allarounder filter.

[Anweniel]

Have to say I have found the O-III quite nice in 5.1" and 4" of aperture, I guess its a question of taste and not having played with one on larger aperture cant comment on the differences, with the added intrusion of the spider @114mm it might be too subtle to be worth the cost.

[rwilkey]

The first thing you notice when using narrowband filters in smaller scopes is the graet reduction in light transmission, but if you can cope with that then you can reap the rewards on feinter and planetary nebula.

Thanks Uhwaz, I didn't know that, I will have to give it a try!

[John]

I've tried a few broadband filters, including the Skyglow, and found that they did not make much difference for me.

Currently my only deep sky filter is an Astronomk O-III in the 2" size. I find it excellent in my scopes from 4" to 10" but it is known for being an O-III with a slightly wider band pass width than some.

As far as possible I prefer to observe DSO's unfiltered though only bringing the O-III into play when it will really make a difference, eg: the Veil nebula.

[crazyjedi]

I have a UHC-S and it does bring out some extra detail in some nebula such as the Dumb-bell nebula but it does reduce your light transmission somewhat. so much so that some of the stars that you use as landmarks to point the way to objects, which can be a bit off putting. I haven't actually seen the ring nebula yet (though i do keep hunting). My scope is a 6 inch newt and I've been told in the past that as a rule of thumb the OIII filters are best used on newts of 8 inches or larger. There are OIII's with wider band pass and hence are better suited to the smaller scope but you'll need to seek them out and try them on your scope to see if they're more of a help than a hindrence.