If you’ve used your ETX in the near vertical position you would have noticed the difficulty in focusing with the telescope in this position. Short of calling the kids whose fingers are much smaller to help – I made this up.

PARTS

• A length of flexible spring cable with insulation – this is commonly sold as curtain wire in hardware shops. Length is your personal choice.
• A small round aluminum rod (couldn’t find a suitable tube … drats!) Mine is 22mm long and a diameter of 10mm – in fact get a couple as this took me 3 gos to getting it right!
• Hex screws (mine come in a pack of 5) and suitable Hex key. Mine were M5 x 5mm purchased from my local hardware store.

METHOD

• Using the hex key supplied with the ETX70, remove the existing focus knob.
• The hard part - Drill a hole right through the length of the rod – it has to be dead center to avoid wobble. The hole should be the same diameter as the one in the existing focus knob.
• Drill 2 holes for the hex screws in the side of the rod – using one hex screw make a thread in the aluminum in each hole.
• Fit the cable to one end (the hole may need to be wider to suit the cable – but don’t drill right through). Then fit a hex screw and secure.
• Fit the other end of the rod onto the ETX focus shaft and secure with the second hex screw.
• Fit the existing ETX focus knob on the end of the cable and you’re done!

When the scope is used on an equatorial mount and is near the celestial pole the scope is perpendicular to the fork arms - as in this illustration, the benefit of the flexible focus cable is self evident.

Return to main page