sparkles in lenses

[Herb Cunningham]

I recently got a very expensive lens that had three tiny reflective spots in the glass. The seller said to shine a flashlight through the lens and see if there were many sparkling spots in the glass. There were, although to call them spots is overstating the size-they are maybe the size of the point of a pin, not the head.

I then got out some lenses and did the same thing, and most had the same phenomenon, some more some less.

Is this part of the glass? What's up with this? The lenses I compare them to were late model Schneiders and Nikons. My Cooke triple convertible also had them. I have experience with most of these lenses and they perform very well.

Just trying to get educated.

[Gene McCluney]

Optical glass can have tiny, microscopic bubbles that can look like sparkles. This is a common thing, although more likely to occur with vintage lenses. These have no effect on performance of the lens.