Experiment with <a href="https://en.wikipedia.org/wiki/Crystal_ball" class="extiw" title="en:Crystal ball">lens ball</a> and light stick<br><small>The lens ball is placed on a glass plate in front of a black background. The light stick (with adjustable light scenarios) was moved behind the lens ball.</small>)
<bdi><a href="https://www.wikidata.org/wiki/Q34788025" class="extiw" title="d:Q34788025"><span title="German photographer and mathematician">Dietmar Rabich</span></a>
</bdi>
<span class="int-own-work" lang="en">Own work</span>