Filtery assistance

[Venus_is_my_friend]

Hello to all,

I am looking at getting some filters and am finding my head a little lost, so help is required please.

I am using them for observational purposes only.

I have a variable polarising filter, which is great.

Light pollution filters don't work, because the lights where I live are white =(

I had been looking at:-

UHC

VHC

OIII

H-Alpha

I am wanting them to be able to see things I can't or to improve views. What would people recommend and for what?

Thank you,

Neil

[John]

I don't know what VHC does I'm afraid. H-Alpa is very specialised and is used for observing the Sun in H-Alpha light so that prominences can be seen - needs a specially designed scope as well as multi-part filtering. UHC and O-III are whats known as narrowband filters and are useful for enhancing the contrast of nebulae. The UHC is probably a bit more versatile than the O-III although both are very effective with certain objects. They work by filtering out unwanted wavelengths of light though so things don't get brighter as such it's just that the admitted light stands out a bit better.

For galaxies and clusters you need dark skies / more aperture / ideally both to get improved views.

[DOBBY]

John said it all... only thing i would add is... using 1.25 inch eyepieces in a Dob up to 12" I'd go for the UHC... for 2 inch eyepieces & above 12" aperture...the OIII gives some fantastic views

the cost... compared to how often you would use them...is down to you

[michael.h.f.wilkinson]

The UHC filter I have in my 2" EPs works a treat, even in my little 80mm F/6. I am going to get an O-III filter as well. This will see most use in the C8, I suppose.

[DazC]

Hi Neil

Go onto primers and toturials section at the top of Beginners help and advice. There's a really good sticky called choosing filters for visual use (or something along those lines). Read that, i'm sure it will help you out.

Happy hunting

DC

[Venus_is_my_friend]

Cheers for the responses.

I was wondering what kind of objects are improved with the UHC and OIII? Are we talking galaxies, nebuleas or other?

I borrowed a UHC filter and tried it on Andromeda Galaxy and it made it worse, as in could see less detail and everything just turned blue.

Someone was saying that H-alpha filters are good at teasing more detail out of nebuleas, does anyone know if this is true or not?

Neil

[John]

UHC / O-III improve the contrast of Nebulae, particularly planetary nebulae and super nova remnants. They don't work on galaxies / clusters -the opposite in fact, as you found.

I thought H-Alpa was for solar but H-Beta can work on a handful of nebulae such as the Horsehead. You will also need very dark skies and a big scope for that one !.

[Venus_is_my_friend]

You just beat me to retract my stupidity.

I assume that because a galaxy consist of many varing types of light that filter are not much good on them (hence was you said)

So basically my stupidity aside filters are good for:-

Polarising - The Moon and bright object (not the sun)

Coloured - The Moon and Planets

UHC/OIII etc - Nebulaes

Is the H-Alpa good for veiwing the Horsehead nebula or just capturing?

Cheers

[GazK]

from my limited experience so far an OIII is fabulous on:

veil nebula

witches broom nebula

dumbbell nebula

M42 (oh wow)

I'm also led to believe its great on the rosette and horsehead but I've not managed those yet.

[Venus_is_my_friend]

Here's the big question then. If you could only afford one would you buy:-

UHC or OIII?

[PreludeToADream]

Here's the big question then. If you could only afford one would you buy:-

UHC or OIII?

I've heard that UHCs are suitable for smaller aperture scopes and OIII are better for larger, as the OIII lets through less light (or something along those lines). However, I think the UHC is more of an all-rounder so perhaps that would be a better option.

[John]

The UHC is probably slightly more versatile but there are some objects where an O-III really delivers more enhancement. It's worth reading the specs as the various brands of UHC and O-III filters have their own characteristics, eg: a Baader O-III is different to an Astronomik or a Lumicon O-III in terms of it's band pass width.

After trying a number of UHC and O-III filters I've settled on an Astronomik O-III in the 2" size as it seems very effective in all my scopes.

[Venus_is_my_friend]

The UHC is probably slightly more versatile but there are some objects where an O-III really delivers more enhancement. It's worth reading the specs as the various brands of UHC and O-III filters have their own characteristics, eg: a Baader O-III is different to an Astronomik or a Lumicon O-III in terms of it's band pass width.

After trying a number of UHC and O-III filters I've settled on an Astronomik O-III in the 2" size as it seems very effective in all my scopes.

Which objects would you say are enchanced with a O-III?

[John]

Which objects would you say are enchanced with a O-III?

The O-III seems to have the most effect on planetary nebulae and super nova remnants such as the Veil Nebula and the Owl Nebula. It can make the difference between seeing something and seeing nothing on those objects.

This report is a little out of date with regards to branding but does assess the impact of the various filter types on different astro objects very well:

Filter Performance Comparisons - Article

[michael.h.f.wilkinson]

I was in the same quandary earlier this year, and opted for the UHC for exactly the reasons given by John.The O-III can wait.

[Demonperformer]

Is the H-Alpa good for veiwing the Horsehead nebula or just capturing?

Ha really refers to two completely separate things. One is for solar viewing, when you need a special (H alpha) telescope. The other is part of the narrowband imaging experience (often with OIII and SII forming the other two colors), which blocks too much light to be of much use visually.

HTH

[Venus_is_my_friend]

Thanks for the continued advice.

I have opted for the Baader UHC, it should be with me soon.

Cheers again!