68 March 2014 sky & telescopeImaging History
Origin of Stacking
Those of us old enough to have cut our teeth
on fi lm-based astrophotography can’t help but
feel a twinge of envy at how easy it has become to capture
impressive images of the Sun, Moon, and bright planets.
These days, people can do it by simply holding a smart-
phone to the eyepiece of a telescope and snapping a few
pictures. Likewise, thanks to ever more sophisticated and
easy-to-use digital technology, amateurs now routinely
capture deep-sky and solar system images that not only
rival those taken by professional astronomers but canactually make valuable scientifi c contributions.
Astrophotographers today regularly capture multiple
images of the Sun, Moon, and planets in rapid sequence
with video or DSLR cameras, then “stack” them together
Stacking multiple exposures to increase the signal-to-noise ratio
in astrophotos today requires nothing more than a few clicks of a
mouse, but the fundamentals of the method owe a large debt to
the darkroom work of two pioneers of astronomy: Earl C. Slipher
(left) and Harold L. Johnson (right). Unless otherwise noted, all
images are courtesy of Lowell Observatory.Klaus Brasch
Modern astroimagers owe a debt to the pioneers at Lowell Observatory.
The
Stacking.indd 68 12/23/13 11:35 AM