Grant Diffendaffer | Astrophotography

31 May Astrophotography

Posted at 14:55h in Photography by Grant Diffendaffer

I made it out to the Sierra foothills over the weekend for a visit with dear friends and some quality stargazing. Dark skies or not, my camera can see far more than my eyes because it can collect light over a long exposure to resolve faint details.

Special gear? A bit, but less than you might think. Just a full frame mirrorless camera with a nice lens, and a compact star tracking mount that offsets the earths motion by rotating the camera gradually and thus reducing star trails and allowing light from faint objects to home in on a pixel on the camera sensor.

I’ve only done a bit of this type of photography, focusing more on photogrammetry, landscape, and macro. My mounting and tracker alignment needs a bit of improvement, but I am already enraptured with the results.

Here are a couple faves from Sunday night:

This first shot shows the benefit of stacking raw photos, which can increase faint light signals.

At left, a single exposure @ f/4.0 150sec, ISO 2000. At right , a stacked exposure of 8 photos.

The photo on the left features just some minimal exposure adjustments in Lightroom, the greatest being a large white balance drop. The photo on the right is the combined light received by eight 150 sec exposures stacked together in Sequator, along with 3 equal length exposures with the lens cap on.

Lens on?!? Yes, in addition to being able to aggregate light signals, Sequator can remove moving objects like the satellite you see above, as well as removing color noise caused by faulty pixels in your camera. To do this, it separates noise from signal by looking at what should be a completely black image (cap on) and selecting for the “hot” pixels to remove later.

The next gallery shows a few starry landscape shots that are all basic long exposures taken on the star tracking mount. No white balance adjustment on these ones (more red in the sky).