Guide :Optics : ETX-125EC (500 x 127mm) Telescope

ETX 125 Loose image when focusing

When i turn the focusing knob in and out the image iam loking at also moves around side to this a repair i can do myself ?

Research, Knowledge and Information :

125 ETX Focusing Problem - Cloudy Nights Home

Page 1 of 2 - 125 ETX Focusing Problem - posted in Meade Computerized Telescopes: My 125 ETX has real bad image drift to the point of the object moving out of the FOV ...
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Weasner's Meade ETX-125EC Comments

FOCUSING - The issue of focusing any ETX is a ... ETX 125's experienced significant image shift but that ... com/etx/guests/guest_125ec_comments ...
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etx 125 focusing Problem - ETX Series - Meade 4M Community

etx 125 focusing Problem - posted in ETX Series: I'm a newbie and am having a problem getting any of my lenses to go into focus. I've tried both celestrial and ...
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Meade ETX 125 Telescope manual focuser knob modification - 2

Intro: Meade ETX 125 Telescope manual focuser knob modification. A replacement for the factory installed focusing knob, which allows precise setup and indication of ...
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Weasner's Meade ETX Accessories Showcase

Telescope Warehouse (email link) provided a #1247 Electric Focuser for the ETX-125EC to me for evaluation. When it arrived it had French instructions instead of ...
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Meade ETX 125 Telescope Manual Focuser Knob Modification

A replacement for the factory installed focusing knob, ... Meade ETX 125 Telescope Manual Focuser Knob Modification. ... It's better to make it loose a bit, ...
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ETX-125EC Reviewed by Sky & Telescope

ETX 125EC-- A First Look. ... Image vibration induced by the ETX-125's drive motors has ... This proved to be most troublesome when focusing.
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Suggested Questions And Answer :

ETX 125 Loose image when focusing

The ETX family (and other Meade LX telescopes), use a moving mirror system for focus. The focus knob moves the main mirror in and out. For smooth operation, there is some slack on the central tube that allows the mirror to rock slightly as it moves. That is a normal condition, and the movement is magnified, the greater the magnification of the eyepiece.
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Can't Focus I just bought a Made etx-125ec from a friend.  I locked onto a bright star and turn the focus to each extreme and cannot get the object in focus.  I was curious if it is possible for someone to damage the focus mechanism by turning it too far.

The focus screw can come out if run too far. Point it straight up, give the side of the optical tube some light 'thumps' and turn the focuser clockwise. You should be able to see the mirror moving backwards in the cell.
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Can't focus using 5mm lens

TOO much magnification for that 3 inch telescope. The most you will get is about 120 power or so on perfect sky nights. Try a 10mm or 9 mm as your most powerful eyepiece. 50 times aperture is the maximum possible.
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Focus. Knob is tight - Meade ETX-125EC (500 x 127mm) Telescope

Remove the OTA from the rear cell; unscrew the focuser shaft about half way (CCW) and remove the knob or electric focuser unit; there are three very small hex cap screws which hold the OTA into the rear cell; remove these and save in a tuna can or similar, because they WILL get lost if you place on the countertop. Once done, merely grasp the blue OTA in one hand with a rubber glove for grip and the rear cell/fork arms in the other hand and pull gently NOT twist while separating! You will see where the threaded focus rod inserts into the OTA....typically binding is causing the shifting, but most of this is due to poor milling by Meade on some 125 models. You can improve these imperfect models greatly, but do not expect to eliminate all focus shift. Run the focus rod gently all the way CCW until you feel NOT force or you will damage. Once there apply a thick grease, such as pure white Lithium (available in the tool dept. at Lowes) in a very thin layer, pushing hard into the NOT apply too much or you risk getting this stuff on the optics eventually. Once done, put the knob on the rod temporarily and run it in and out all the way slowly about 3-4 times. Once done, run it HALF-WAY between all the way and all the way out and stop. At that position, turn the OTA to about a 45-degree tilt, with corrector down and put 1-2 DROPS of 3-in-1 oil right where the threaded rod goes into the threaded rear cell of the scope and QUICKLY run the focuser CLOCKWISE to get that thin bit of oil into the rear cell threads. Once done, run the threaded rod slowly all the way CW and then CCW about 2 more times. This procedure will greatly improve the performance....NOTE: do NOT put more than 2 drops of oil on the rod!
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Can't focus my meade etx-125. have turned focusing control more than 80x in both directions. Is there an stop on the focusing system. Originally had the electric focusing system on the scope couldn't focus then either. I have tried both indoors and out doors.

Yup there is a mechanical stop to prevent you from cracking the mirror by retracting or extending it too far.. once you break the pin off it needs to go to the factory for dis-assembly as they have to remove the primary to get to it and realign it my 105 did same thing....word of advise use a cable extender for focus not an electric focuser they fail to tell you that it can over run the built in stops making your scope useless...i may be mistaken but i believe the max turns is 25 or about for end to end focusing adjustment on the 125
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Focus Issues I have a Meade etx-125ec unit. I am unable to focus on any image. It appears the focus knob is loose and sloppy. It turns real easy and never gets the object in focus. Any suggestions on correcting this?

Try tightening the grub screw that fastens the knob onto the shft that it turns. Better still, buy a flexible extended focusser which makes focussing much easier. Check on eBay for "Meade flexible focus"
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OK, that model has an internal adjustment. A good source for all kinds of information and tips on the ETX series is available from:
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Loose image when focusing

The focus knob can have the play reduced. Turn counter-clockwise a turn or 2, then loosen the knob's set-screw and carefully turn clockwise until a little drag is felt. Then tighten the set-screw.A further item that may pertain to image shift, especially at low powers, is that the baffle tube that the main mirror slides on, may be loose in the back housing. There have been reports of poor thread engagement due to poor tolerences. That tube can be re-tightened - just be careful not to strip the threads!.
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Etx cant focus

The LPI camera will HIGHLY magnify the image-- about like a 6mm -8mm eyepiece-- tiny adjustments are needed to focus. You can buy a .5 or .3 focal reducer which will widen the field of view and make it easier to focus--On my LX90 --- it takes about 20 TURNS of the focus knob to go between the eyepiece view and the camera view!
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