PSU_February_2016_PDF

PHOTOGRAPHY SECRETS › ›
saturated with stars at the end of the Photoshop process. Before wrapping up, I shot ten “flats” at each shutter speed, twelve “darks”
at each shutter speed, and ten “bias” frames for the pre-Photoshop processing in software that “stacks” the images together.
“Flats” are images taken by covering the end of the lens with a white T-shirt and shining a flashlight on it. They’re used by the
stacking software to correct any difference in brightness in the main images. “Darks” are images taken by covering the end of the
lens with the lens cap. Half of the darks are taken at the beginning and the other half at the end. Darks correct the dark signal
flaws in image sensors. “Bias” frames are images taken with the fastest possible shutter speed the camera can shoot and the lens
cap on. They contain only the noise generated by the camera’s electronics on the sensor. This noise is subtracted from the data in
the darks to identify the true sensor noise. These extra images are time-consuming but they’ll allow you to create the best possible
final image.
Learning To Run
Adding more sophisticated equipment, such as a bigger telescope and mount, will yield larger, more detailed images of your targets.
For comparison, here are images of the nebulae in Orion taken through a 4" Takahashi refractor on a Celestron CGEM mount. The
equipment investment is now in the $3,500 (used) to $5,000 range (new). The targets are much larger in the frame with more detail.
Horsehead and Flame Nebulae in Orion
› › photoshop user › february 2016
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Running Man and Great Orion Nebulae