After reading Robert Bruce Thompson's books (Astronomy Hacks, & the illustrated guide to astronomical wonders) I only bought filters in the 2" size, with my 1.25" adapter which is threaded for filters I can use them with any size ep! Buuuttt!!! be careful because some ep's are have long field stop tubes (the part that enters the adapter) and is soo long that it they could damage the filter! RBT didn't mention this in his books, so I'll tell you, only buy 2" filters if you have an adapter threaded filters, if you don't buy one! (its cheaper than filters) But that said, I don't screw in filters anymore! I just pass them between my eye & the eye piece! That too I read in Walter Scott Houston's deep sky wonders book! He called it the blinking method, and it works really well! Once you can see the nebula, just lay the filter on your ep! Cheers pay less & have fun! Shawn Haggerty Avignon, France
> Message du 01/06/08 05:37
> De : "Phil Lefever"
> A : email@example.com
> Copie à :
> Objet : Re: [skyquest-telescopes] OIII filter for XT8
> > At 11:52 AM 5/31/2008, you wrote:
> >If I were to get an OIII filter for my XT8 should I get a 1.25" (for my
> >Pentax 10.5 & 14mm) or the 2" (for my GSO 30mm).
> The primary use I find for my OIII filter is for observing the
> Veil nebula, since this is a large object I had to but a 2"
> format model. I do use a 2"-1-1/4" adapter that is threaded
> for 2" filters with my smaller eyepieces from time to time.
> >Maybe more importantly, should I get one at all? Is 8 inches of
> >aperture enough to make an OIII useful?
> I have used an OIII filter with good results in my 80mm
> scope a number of times. I don't feel there is a minimum
> aperture for an OIII. It is important that you use the filter
> on the correct objects though. As John mentioned be
> sure to buy a narrowband/UHC/Ultrablock filter first as
> they are far more useful. Still the OIII does wonders on
> those few odd objects, like the Veil nebula and some
> Clear Skies,
> Phil Lefever - Burnsville, MN
> Amateur Radio Callsign - KB0NES EN34jt
> C8-SP XT-10 C102 80WV
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