(Viewed 567 times)

[dweiland]

Hello Astonomers!

I have a question about 2 inch/1.25 inch convertible eyepieces - specifically, I've been reading reviews about the 13mm and 8mm Tele Vue Ethos products.

I am somewhat confused by how the diameter of the eyepiece relates to the field of view. For instance, is it better to have a 1.25 inch diameter eyepiece with a 100 degree field of view or a 2 inch eyepiece with a 100 degree field of view? Or... are they equivalent?

Both 13mm and 8mm Ethos eyepieces come in a design that allows you to use in 2 inch slots or 1.25 inch slots. Does this really mean that the eyepiece is a 1.25 inch in diameter?

I'm wondering if people that are so enamored with the Ethos line have telescopes that can only fit 1.25 diameter eyepieces.

Very Grateful,
Dave

[Chicago Astronomer - Astro Joe]

Dave,

The Ethos line is supposed to be a great series of eyepieces.

Well beyond my budget, I don't have first hand experience with any, but the 2" eyepiece funnels more light to the observer than the 1.25" one do.

Although both may offer a 100 degree view, the 2" eyepiece will be brighter and the eye relief much more comfortable. One literally swims in the Field of view.

While the 1.25" eyepiece funnels light straight through, the 2" eyepiece allows the image to "expand" to the bigger glass area, allowing the photons to stretch out and relax...providing excellent views.

Please provide a link on the conversion eyepieces.

[dweiland]

Hmm...

That is interesting. I'm now curious if observers who are fond of the 2 inch barrel diameter look away from Tele Vue for premium purchases.

A link, with pictures, that depicts what I'm talking about can be found here:

www.cloudynights.com/item.php?item_id=1792