As a night photographer on Cape Cod, one of the tools I rely on most for capturing the Milky Way is the Pentax Astrotracer. Built into select Pentax DSLRs, Astrotracer offers a clever alternative to traditional star trackers, using the camera’s in-body GPS and sensor-shift mechanism to counteract Earth’s rotation and keep stars sharp during long exposures.
Surprisingly, not a lot of people I run into have heard of it! When they do, they seemed to be amazed an inquisitive as to how this works.
How Astrotracer Works
Unlike external star trackers that require polar alignment and extra setup, the Astrotracer works from inside your camera, in my case this is the Pentax K1. By syncing GPS data with the camera’s orientation sensors and taking into account the lens that is attached, the Astrotracer calculates how the camera should move the sensor to follow the stars. This internal tracking is a game-changer for portability and speed, especially when you’re working at night and moving between locations. And this tech is several years old! To the best of my knowledge, no other manufacturer has a similar feature.
The advantage to tracking is the ability to leverage time as an asset, not a restriction. This allows for lower ISO shooting and even using kit lenses to capture the Milky Way because longer exposures can do all the heavy lifting of collecting the light. Star trails no longer appear as quickly since the camera is moving along with the sky.
Lucy Vincent Beach, Chilmark, MA – Tracked and Untracked blend with light painting using the Pentax K1.
Astrotracer vs. Traditional Star Trackers
Traditional star trackers like the iOptron SkyGuider Pro or Sky-Watcher Star Adventurer offer precise tracking over long exposures and work with virtually any camera system. They’re the standard for astrophotographers aiming for deep-sky objects or stacked Milky Way panoramas. However, they’re bulkier, require a careful polar alignment, and sometimes need counterweights and accessories.
The Pentax Astrotracer, by comparison:
- Is faster to set up – no polar alignment required.
- Integrates directly with your camera – no extra gear to carry.
- Ideal for short-to-mid exposures – usually up to 2-5 minutes with a wide-angle lens.
On Cape Cod, where fast-moving weather can limit my window of opportunity, that simplicity means more time shooting and less time setting up. On most nights, I can be up and running in just 2-3 minutes.
Fort Hill, Eastham, MA. Tracked sky using a 50mm vintage lens on the Pentax K1.
The Three Astrotracer Modes
For eligible cameras, Pentax introduced three Astrotracer modes to better match different night photography needs:
- Astrotracer Type 1 (Standard Mode)Tracks the stars to maximize exposure time without star trails. Best for star fields and Milky Way core shots where you want pinpoint stars.
- Astrotracer Type 2 (Reduced Blur Mode)Prioritizes reducing blur in both stars and foreground elements by compromising tracking slightly. Useful for scenes with important terrestrial features.
- Astrotracer Type 3 (Self Calibration)Takes a “test shot” and then calculates the appropriate tracking rate based on data from the image. Useful for Pentax bodies that did not come with the GPS module.
Drawbacks
Of course, everything comes with a price. In this case, it comes down to editing.
When photographing using Astrotracer (or tracking in general) in which the foreground is an element of the composition, a second untracked shot must be captured and blended with the tracked shot in post production.
This may not always be an easy task because anything that breaks the skyline such as telephone poles, wires or trees can become a blending nightmare. Remember, stationary objects captured while the camera is tracking the sky become wide and blurred. There are ways around this to some extent like using the remove tool in the tracked images to get rid of those elements entirely. This makes it easier, all though takes more time and attention to detail.
Ideally, we’d all love to have compositions that were split by a clean horizon but that almost never happens…at least not for me!
Final Thoughts
While traditional trackers have their place, especially for deep-sky work or long lens astrophotography, I’ve found the Pentax Astrotracer to be a powerful, streamlined solution for Milky Way photography. Despite being “old tech” by most standards, it is the primary reason I have not moved to another camera system after all these years. Quite honestly, I can’t live without it!
Coast Guard Beach, Eastham, MA.
