3 ms·

Can anyone explain the faint crosses on the photos? I've always been curious why they are there. See an example here: http://www.hq.nasa.gov/office/pao/Histo

• trafficlight 16y ago
  It's called a reseau grid. The crosses are used as a reference points for measuring distances between objects in the image. They can also be used to correct distortions after development or scanning.. This page talks about it in detail. http://www.clavius.org/photoret.html http://www.clavius.org/photoret.html