Anyone know how a zoom eyepeice works?

[petermarknimmo]

Browsing the telescope house website has made me wonder about zoom eyepeices, and to be honest, I'm just being a bit curious as to how they actually work. Anyone know how?

[dtr42]

http://www.madsci.org/posts/archives/2003-11/1069817936.Cs.r.html

[LukeSkywatcher]

Good question. I have a Baadar Hyperion 8-24mm which works great. I just dont know how it works. Maybe somewhat like a gear box in a car?

[AndyH]

Mmm.

The way I see it is......

It can be thought of as like a standard fixed focal length eyepiece with a moveable Barlow lens, although some of the eyepiece elements may also move. By varying the distance(ie: twisting the barrel) between the eyepiece and Barlow, you thereby vary the magnification.

Andy.

[petermarknimmo]

Good point andy, i had a different idea that perhaps the lens was an irregular shape and that by twisting the eyepeice different areas of the lens are exposed, thereby changing the magnification, but I would say andy's idea is more faesable.

[Stargazer_00]

I figured that twisting it moved the first lens in the EP along a screw thread thus changing its distance relative to the other lens groups. this would account for the change in FOV as well I believe? (dunno).