Cleaning Telescope Eyepieces and Lenses

Introduction

Telescope eyepieces tend to get dirty over time due to various reasons - fingerprints, eyelash oils, mascara, dust, etc. Usually there is no need to clean the eyepiece too often, eventually the dirt and the oils will visibly affect the views and you'll want to clean it.

Most of the eyepieces have anti-reflective coatings which are quite durable, so cleaning (when done properly) usually won't leave any marks.

I'll describe a method I'm using without any issues for over 15 years (I clean my eyepieces every year or so). It's partially based on guidelines by Televue.

I've only cleaned eyepieces using this method, however in theory it should work for refractor objective lenses as well (though for those I'd try using larger cotton pads instead of Q-tips).

Equipment

The equipment you need is quite basic:

• Clean distilled water - preferably from a pharmacy and not the water used to refill car batteries.
• Pure alcohol - preferably 95% or higher (either ethanol or methanol will do).
• Bulb blower.
• Cotton Q-tips (make sure they are 100% cotton). If you are cleaning large glass surfaces consider cotton pads.
• Clean table near a window or a strong light source.
• Two clean cups filled with water and alcohol.

Cleaning Process

1) Prepare your eyepiece - open the caps and if possible and remove the rubber eyeguards to allow easier access to optics.

2) Take a few Q-tips out. For 2-3 of them I like to slightly pull and tear (or cut) the tips to make them "bushy".

3) Dip the Q-tip in the alcohol (