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Meade QX lens sequence

Started by jcboyd, 04/28/2010 09:58AM
Posted 04/28/2010 09:58AM Opening Post

Well...a 9 year old has no trouble taking a Mead QX 36mm eyepiece apart, but this future Al Nagler is in the Meade phase of his development. He said he took them out in order, but got them all mixed up when he tried to put it back together. Can anyone give me some help with this one.

There is the field lens in a top spacer.
Thre is a 2 element convex lens about14mm thick (at the edge
There is a spacer 14mm thick
Thre is a convex/flat elememt 3mm thick (at the edge)
There is a 3mm spacer
Finally a convex/flat doublet 9mm thick at the edge.

If anyone has the seguence or a drawing of the assembly design, I would certainly appreciat some assistance on this one. I would like to say it is a great lens, but I never got the chance to try it. Thank you very much for any assistance provided.

John Boyd
Titusville, FL
Posted 05/05/2010 06:20PM | Edited 05/07/2010 09:13PM #1
Hi, in lens terminology, *flat* is refered to as Plano, so your convex-flat is a plano-convex lens. Given the lens elements you listed, it would seem the 32mm QX is an Erfle variation design with perhaps a Barlow as your field lens; the 20mm & 15mm QX are classic Konig designs with an added Barlow. I'd apply the plano-convex as the eyelens with flat side towards eye, the thinner achromat plano-convex doublet in the middle with its' flat side towards eye & the thickest achromat double-convex doublet as the actual Field lens with its' greatest curved surface facing the curved surface of the middle achromat, followed by the Barlow that you assumed was the field lens. That arangement should place the thinner spacer between the eye lens & middle lens with the thicker spacer between both doublets, but their curved surfaces will inform as to correct spacer placement; reverse the orientation of that double-convex achromat Field lens if spacer or performance dictates.