Yosemite astrophotography – May 23, 2025
This is a pretty short post just detailing my experiences using a star tracker for the first time. My astrophotography photos usually consist of a foreground shot taken at blue hour (or a very long exposure taken at night if I can’t be on site earlier) and a sky shot consisting of multiple stacked shots at high ISO. Stacking often reduces noise to acceptable levels, but the high ISO destroys much of the dynamic range which can’t be recovered by stacking.
The star tracker allows for drastically longer exposures at lower ISOs, which helps to bring out the vivid colors of the Milky Way. This first shot was taken at Glacier Point.
Sky: 600 s, f/1.8, ISO 200
Foreground: 300 s, f/1.8, ISO 640
Milky Way over Glacier Point.
I’m very happy with how the Milky Way turned out here. Note that this shot was facing nearly due east so the core of the Milky Way isn’t visible. Outside of the core, I find that it’s harder to get good definition in the Milky Way with my previous workflow, but the colors are super vibrant here.
For the next shot, I headed down to the valley to try and capture the Milky Way over Cathedral Rock. One detail I neglected to plan for was the cliffs on the north side of the valley completely obscuring Polaris. The star tracker requires polar alignment with Polaris to function properly. Since I couldn’t figure out how to do the alignment, I decided to just go with the fallback of stacking sky shots. I recently purchased a 14-24 f/2.8 lens which I had hoped would work for astro as well. A major issue I had with this lens was finding stars to focus on in the pitch darkness. My 20/1.8 prime lens has no problem seeing bright stars but this lens made it particularly difficult. I really needed something wider than 20mm for this shot but gave up on the zoom and switched back to the 20mm.
Sky: 15 s, f/1.8, ISO 3200 (x32 shots)
Foreground: 240 s, f/1.8, ISO 1000 (I probably should have exposed longer as lower ISO but headlights from cars driving by were a big problem)
Milky Way over Cathedral Rock.
I find that the core of the Milky Way is much easier to capture even with suboptimal exposures. I was really looking forward to see how much more detail I could get with the star tracker but it wasn’t meant to be this time. I’m already planning to return and try this shot again with a wider lens and hopefully even capture a reflection of the Milky Way in the pond pictured above.
—Justin
