On Wed, 15 Jul 1998 16:15:44 +0800, Ong Soh Khim wrote:

>I have recently tried to clean my Nikkor 20mm lens after coming back
>from an overseas trip. It appeared that there is a stain on the rear
>lens, in the shape of a curly alphabet g. After some light rubbing with
>lens tissue and lens fluid, the stain came off a little.
>
>However, on further rubbing, the strokes of this so-called curly g
>merged to form a "hole" on the lens. What exactly happened to my lens
>when I cleaned it? Did I scratch the surface of the lens and cause the
>"hole" ? What should I do now?

Chances are this is a bit of grease causing the reflectivity of the
lens surface to be different. To check this, slightly moisten a clean "Q-tip" (small cotton swab) with lighter fluid (naptha) and lightly
wash the spot with this. Finish by breathing up on the glass to moisten it, and use a clean "Q-tip" to lightly polish the area.
Further cleaning may be needed to restore the entire surface to
clean (avoid silicone-based "cleaners"!!!), but if the "g" disappears,
you are OK...