Star Trails over Mt Lemmon

Click image to see it at 33% size

Thirty 2 minute images were combined in Adobe Photoshop using the technique described in the March 2004 edition of Sky & Telescope.  In this technique each image is added to previous images as a 'Lighten' layer.  This only adds pixels in the new image that are brighter than pixels in the existing image.  This lets the star trails build up without increasing the sky background glow or overexposing other objects in the image.

Equipment Used

Telescope None
CCD Camera Canon 10D SLR with 28mm Lens
Focal Ratio
Guiding N/A

Image Durations

Duration (secs) Binning
Luminance 120s x 30 @ ISO 200 1x1
Red N/A N/A
Green N/A N/A
Blue  N/A N/A