Veteran astrophotographer Gregg Ruppel, will be featured at the Saint
Louis Astronomical Society’s February meeting. If you think
you might be interested in CCD photography and want to know what it
takes to get started, this program is for you.
Photographing astronomical objects has for decades been as much art
as science. Except for the Moon and the brightest planets, the objects
are very faint, which means that film must be exposed for long periods
- typically tens of minutes - to build up enough light to form
an image. Because a telescope magnifies the object’s apparent
motion (the rising and setting motion due to Earth’s spin) as
well as the image, a telescope must be guided during the entire length
of the exposure to keep the object centered and the picture free from
streaks. The invention of digital imaging and “CCD’s (charge
coupled devices, the forerunner of today’s digital cameras), radically
changed astrophotography. Recently the cost of CCD cameras has dropped
substantially, so that many amateur astronomers can afford them. CCD
photography reduces exposure times by factors of ten to fifty.
The ability to process raw images and stack multiple exposures
has allowed amateur photographers to produce images possible before
only at professional observatories.
Gregg will present the basics of CCD imaging - an introduction
to the equipment and techniques necessary for digital astrophotography.
He will also discuss how to locate interesting objects, focus the images,
and guide the telescope during exposures. He will describe image processing,
including image calibration, use of filters, multiple exposures, and
contrast and color adjustments.
Gregg Ruppel has been an active amateur astronomer for over thirty years.
A CCD astrophotographer for five years, he was named the National
Air and Space Museum’s Featured Observer for November 2002.