GSO 'ED' eps

Regulus (Trevor) · #1 09-02-2014, 03:58 PM

What are they, and what do they do?
Are they specifically designed for ED scopes, or are they made with ED glass.
Do they provide some CA correction?

They are cheap so I doubt they do anything profound but....

Trevor

AG Hybrid (Adrian) · #2 09-02-2014, 05:27 PM

They are made with ED glass. They do not reduce CA in an achromat telescope. If they did they would be a lot more famous then they are.

Regulus (Trevor) · #3 09-02-2014, 06:33 PM

Thx Adrian.
I am a bit surprised at the price then. Admittedly it is only a small bit of glass, and I suppose, it is designed and made in China rather than the USofA.
So more faithful colour transmission and reduced light dispersal/reflection/refraction??
Wonder why the cheaper chinese lenses sold by 'Brand Name' companies don't use it as well?

Anyway, thanks again - Trevor

Larryp (Laurie) · #4 09-02-2014, 07:53 PM

I had 2 of these eyepieces a few years ago, Trevor-couldn't wait to get rid of them. They were like looking through a piece of water pipe.

Regulus (Trevor) · #5 09-02-2014, 11:04 PM

Thanks Larry,

I don't think I would buy them but I was curious about what they were. The ED appellation usually comes with a bigger price tag.
I was in half a mind to try the GSO 2.5x ED Barlow out of curiousity though, since I only like barlows for quick, brief, high mag looks at solar system objects when I have the crazy thought that I want to see something at a mad magnification (so I can experience the joy of what it would feel like to own one of those scopes they advertise: 575x magnification!)

Trevor

jjjnettie (Jeanette) · #6 09-02-2014, 11:43 PM

I really do like my ED2.5x barlow.
They are amazing value for the price.
I used to use it for afocal planetary imaging with my old 10" Dob with a 12.5mm ep slotted in place, and it did the job nicely.

astro_nutt · #7 10-02-2014, 12:57 AM

Hi Trevor.
For the CA issue with your scope, enquire about a minus-violet filter.
Cheers!

AG Hybrid (Adrian) · #8 10-02-2014, 11:23 AM

Actually I agree. The GSO ED Barlows are excellent. The 2" ED barlow was tested for light throughput and returned a result of over 99%. Practically no light scatter was introduced by the barlow.

If you want the source you will have to find the post on Cloudy Nights.

Regulus (Trevor) · #9 10-02-2014, 03:17 PM

Thx folks,

That's a nice result from the Dob Jeanette and I will go ahead with the 2.5GSO given yours and Adrian's comments.

As to CA correction I have been following other threads discussing the relative merits of CA reduction via filtering.
http://www.iceinspace.com.au/forum/s...d.php?t=117179
and various archived material here and cloudynights etc.

Trevor