Subject: etx-125 focus shift Sent: Thursday, April 14, 2011 19:18:27 From: firstname.lastname@example.org (email@example.com) I purchased an ETX-125 last fall and over the winter, without having any good clear nights for viewing, I religiously tried to learn more about this great little scope and making any improvements that might be learned from other users. One thing that I kept noticing was complaints about FOCUS SHIFT and I noticed a post from a user that it could be reduced by using a short section of soda straw over the shaft forward of the focus knob reducing the "play" in the shaft into the rear of the scope. I was concerned that the straw might become "lost" inside the scope so here is what I did. I had an old FM radio antenna and noticed that one of the sections was exactly the right diameter to slide over the focuser shaft and slide inside the plastic hole at the rear of the scope creating a "bushing" to take up "play". I flared one end of the antenna section by driving it into the slotted end of a dry wall screw. Next I cut off about 1 quarter inch of the antenna tube with the flare, scraped off the chrome plating and put it over the focuser shaft, pushed it into the rear of the scope, and most of the focus shift was gone. The flare keeps the new "bushing" from getting inside the rear of the scope. A small dab of glue on the outside keeps the "bushing" secured and a small amount of lithium grease will lubricate the bushing.Mike here: There are many other articles as well on "image shift" on the Helpful Information: Telescope Tech Tips page.
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