OIII Filter -1.25" or 2"

[Bart]

Hello All,

I wondered, if I was going to buy an OIII filter, will I be using it mostly in in low powered 2" situations, or middle/low mag 1.25" situations. I have 1.25" and 2" UHC filters (I know! thats the need to spend demon inside me driving me on while there's clouds and no darkness around). Thanks for any views.

Bart

[Moonshane]

my logic was that if I bought 2" then I'd use it on mainly my 26mm 2" eyepiece and 13mm (converted to) 2" eyepiece so few changes. for those situations where I use it with 1.25" eyepieces, I screw the filter into the 2-1.25" adapter - make sure that there is enough space to do so - I used a 14mm Baader FTR to extend the adapter.

[Andrew*]

I think you will find yourself using it in all situations, from very low power on the veil nebula to 150x magnification on planetary nebulae.

I would suggest you buy a 2" filter, which you can also screw into a 1.25" adaptor for 1.25" eyepieces. This has the added convenience that you can change eyepieces without having to rescrew (is that a word) the filter each time.

[Damo636]

I use a 2" Bart but I really only use it for the Veil Nebula so its mostly in my lowest power 2" eyepiece. With the 1.25" version you will be tied but with the 2" you could screw it into something like the Antares twist lock adapter for use with 1 1/4 ep's also.

Edit. I have checked my 2"- 1.25" adapter (same as yours) and its already threaded to accept 2" filters so the above isn't necessary.

[Bart]

Thanks folks, I have the Antares twist lock adaptor, but didn't realise the filter could screw into it. If thats the case, I probably shouldn't have got the 1.25" UHC! Mind you, can't remember if I got the 1.25" UHC before or after the adaptor. Anyway, thanks for the help. This site is invaluable, it makes me realise how much money I've wasted! I can't wait to use it with the new 30mm 82 degree. Nice.

Bart

[rwilkey]

I find the OIII and the UHC more useful in the 2" size as they are for wide-field nebula such as the Veil etc, you can always use them with 1.25" ep's by screwing them into the 2" - 1.25" adaptor.

[swamp thing]

I would also go for the 2" filter. Another bonus with the larger ones is they are easier to hold up to your naked eye and use on their own.