OIII - So that's what it's for!

[Rick Parrott]

My OIII Filter arrived in the post yesterday, and we had the opportunity to try it out last night for a short while!

Eta Carinae Nebula
Tried "with" and "without" comparisons; the filter really shows a much larger area of nebulous gas and dust than without, and it seems to provide an almost "3D" depth to it! Very nice!

M42
Similar results to above, I also noticed it seems to make the nebula appear more "fan" like. The Trapezium seemed to be sharper with the filter, though that is likely my imagination!

The Jewel Box
I know it is not for this purpose; I just wanted to see. Turns a nice view into a fairly crappy view! :lol:

Very pleased so far; especially as I had to mumble the price into my hand when my wife asked how much it was... :D

All tested in our 12" Dob, with 30mm Plossl, 20mm wide view, and alternating with 2X Barlow.

[BeanerSA]

Which one did you buy?

[Rick Parrott]

An Astronomik 1.25", from Bintel.

[BeanerSA]

I'm not questioning your decision, but how did you make a decision between the OIII or the UHC?

[Rick Parrott]

Financing dictates 1 at a time; UHC is next on my wanted list (amongst about 20 other things! :lol:)

Would you have recommended the UHC first?

[BeanerSA]

Yup, I get that!



Not at all, just having problems making that decision myself. Will probably go for the UHC though.

[AEAJR]

I have both an OIII and a Nebulea filter. You can see them in my signature. These were some of the resources that helped me decide what to get.


Filter review
http://www.astronomy.com/~/media/import/files/pdf/8/c/7/0805_nebula_filters.pdf

Filter overlay chart
http://www.karmalimbo.com/aro/pics/filters/narrow.jpg

[BeanerSA]

Thanks Ed.

[glenc]

I have a UHC and an OIII filter.
I mainly use the UHC because the OIII makes the background much darker.

[raymo]

You're missing out on some optimal views Glen; many nebular objects
are better with the OIII. A good example is the Veil Neb, which is MUCH
better with the OIII, stunning. If you google the Prairie Astronomy Club
you will find results of testing, rating filter efficacy on 95 nebular objects.
raymo

[glend]

I prefer the DGM NPB Nebula filter for all visual nebula work. OIII is smack dab in the middle of lthe sun light reflected from the moon, which is why it really can't be used for narrow band imaging when there is any moon light around. It passes teal coloured light around the 520nm part of the spectrum. There are reviews of the DGM NPB published online and in pdf via Cloudy Nights forum - worth a read.

[Allan]

A new star is full of hydrogen. As it burns this hydrogen it fuses it into Helium, and in turn as the Helium burns it fuses it into Oxygen and Carbon. So at the end of a stars life it is all Oxygen and Carbon, and it is this that is thrown off into space to become what we see as a planetary nebula.

Hence the reason the OIII filter is the best filter for observing planetary nebula, because it isolates the the 2 main OIII lines that the planetary nebula are made off, for maximum contrast.

A UHC filter also isolates these OIII lines, but other wavelengths as well, which will show you a brighter image, but without the absolute contrast you see in the OIII filter.