|"Mt. Shuksan Reflection" - Click image to enlarge and see the low-noise quality due to tracking ~ © Rick Parchen|
Rick Parchen is one of several astro-landscape photographers who are using star trackers or equatorial tracking mounts to improve the quality of their night sky exposures. Tracking allows one to use longer exposures without producing star trails. Instead of using ultra high ISOs and large apertures to reduce their exposure time, photographers can use a tracker to lengthen the exposure time and use smaller apertures. With a tracker, a photographer is able to align his camera to Polaris, the North Star; and a built in servo motor keeps the camera tracking the stars at the same speed the earth rotates. Editor's Note: Rick was one of the early pioneers in astro-landscape "tracking" photography. This post originally appeared in October 2013.
The old way: Astro-photographers have been using equatorial mounts for decades to photograph the stars through their telescopes, but early astro-landscape photographers who included a landscape feature in the foreground didn't use these mounts because tracking the stars cause the landscape to blur! The standard solution has been to keep exposures at 30 seconds or less, following the "600 Rule" —requiring very high ISO settings that produced noisy images. (Additionally, equatorial mounts for telescopes were expensive and too bulky to carry into remote areas.)
A new approach: Because of the recent popularity of nightscape photography, newer mount designs, just for cameras, have appeared that are smaller and less expensive. Using these smaller and cheaper trackers, a new breed of astro-landscape photographers are taking a tracked exposure for the sky (referred to as "wide-field astrophotography"), a second exposure for the landscape (without tracking), and then blending the two in post-processing.
Editor's Note: Another inexpensive and compact tracker is the Polarie Star Tracker from Vixen Optics. And, if you're handy with tools, you can build your own "barn door" tracking platform. (I believe all of these trackers are accurate enough for tracking stars with a normal to wide angle lens, without the need of a spotting scope attachment —which is only necessary if you are using a telephoto lens on your camera.) Both the SkyTracker and the Polarie come with Polar sight holes. The SkyTrack includes a Polar scope for greater alignment accuracy, whereas the Polarie's Polar Axis Scope is a $129 add-on accessory. The instruction manuals for the SkyTracker and the Polarie should help you decide which unit is best for you. The Orion Telescope people produce two inexpensive equatorial mounts that are adaptable for astro-landscape photography. Their manual tabletop model is under $70, and their motorized unit is under $180. (You may wish to throw away their low-quality tripods and attach the units to your regular camera tripod.)
|Another view: "Path to Mt. Shuksan" ~ © Rick Pachen|
Rick Parchen is a Seattle-based landscape photographer who has an appetite to travel to the world and share the extraordinary view with others. "I started this adventure seven years ago and only find myself more enveloped in chasing light and setting my work apart from others. I'll travel for weeks at a time, research for months, drive thousands of miles, and walk to near exhaustion all for the potential of a perfect image. But my passion goes far beyond just seeking the sights; the real pleasure comes when viewing the art in print and putting it on display for others to enjoy." More of Rick's photography can be seen on his Facebook page, and at his website.