You may have noticed a slightly different look to my astrophotography as of late. The reason is that I’ve taken a little bit of a risk on something I’ve found that might replace… well… just about all of my astrophotography gear.
While doing some research on astrophotography, I stumbled across some interesting articles about Pentax cameras’ “astrotracer” function. My first reaction to this was hesitation. I’ve seen a lot of unique features on cameras that end up being sales gimmicks. Still, the chance to downsize my personal belongings is always a concern for me as a priest. So… I took the risk. And… so far… risk well taken!!
So… what is astrotracer? To simplify how this works lets talk in layman’s terms about how you take nice astrophotography images. First, you need a lot of light. Most of the images you capture when doing astrophotography are of faint objects with colors we can’t see. Therefore, we need to expose film or a camera sensor for long periods of time to collect the proper amount of light. There is one problem with this – We’re constantly moving. Because of this, there are limits as to how long we can expose film or a sensor before we get what are called star trails. For artistic reasons, star trails can be desirable. However, if you are trying to image a deep space nebula, star trails are not desired. Here is an example of star trails over our family farm.
To eliminate star trails, you have one of two options: 1. Figure out how long you can leave your shutter open before star trails occur, take a lot of images at that shutter speed and then stack the images with special software; or, 2. Find a way to track the stars so you can dramatically increase the time you can leave your shutter open.
I’ve always felt like my best results have been a combination of points one and two. What I mean is that when I can take a 2 minute exposure many times and then stack them, I get the best results. Up until now, the only way to do this was to buy (or build) a tracking mount to move the camera.
If you’re thinking, “Wow… that sounds like it gets complicated and expensive,” your intuition serves you well. Therefore, trying to do things “on a budget” is something I constantly strive to achieve.
Enter the Pentax K-1 with an astrotracer function. Pentax has a unique function in its cameras that slightly moves the sensor to track the stars in camera. Depending on what lens you use, this tracking can work for up to 5 minutes with ultra wide lenses. The feature image I used in my last post was taken with the Pentax astrotracer and an Irix 11mm f/4 lens.
When you look at this image, you will find an odd phenomena where the center stars are nice, sharp and round while you see trailing on the outside stars. This is due to the natural distortion that occurs with all ultra-wide lenses. Therefore, if you want all the stars to be pinpoint sharp, you will still need a tracker with a wide angle lens or reduce your exposure time. The above exposure was 5 minutes. Therefore, reducing the exposure time to 2 minutes would dramatically decrease the trailing effect. For me, I like the effect. I can see this adding visual interest when doing landscape photography.
At longer focal lengths this trailing effect does not occur. Usually telephoto lenses have more issues with trailing than wide angle lenses. It seems so counterintuitive with astrotracer that the opposite is true. For example, below is a capture of the Rho Ophiuchi cloud complex with a 77mm lens… for three and a half minutes! Typically, you would be lucky to get a three second exposure with a 77mm lens. The left image is what it looked like out of camera, while the image on the right contains simple edits to brightness, contrast and white balance to start pulling out some details.
For those not familiar with astrophotography, you may be rightly thinking, “These don’t look all that inspiring.” Most astrophotography images out of camera have this flat feel. That is why in addition to learning proper capture techniques, proper editing is just as important. I am no expert with editing, but here is an example of how much detail you can pull out of a one, three-and-a-half minute capture. With a few more basic edits and cropping, we can start seeing the “information” the image contains, bringing the picture to life… along with a satellite that spit the image in half.
With more exposures, stacking them and then editing, I’ll have even more usable information to make this popular target for astrophotography shine!
So… does this mean I’m selling all my astronomy gear? Not yet. Obviously I want to keep my telescope for observation. I also have a small monochrome camera I’m going to use to attempt a little science. That being said, it is nice that I might be able to do astrophotography without the use of a tracking mount in the future. As a priest, I don’t have a lot of time in the field to futz with gear and settings. This neat function might help me both declutter my life and maximize my imaging time.
I’ll keep you all up to date on how it goes!!!! And, if you were wondering… yes my other images from my last post were taken with the K-1 too. I’ll post the reminders below. There are also fun star trail and star “tracing” features in the camera! I tried my first star trace last night. I’ll post the video below.
Happy Monday and get out and enjoy God’s creation!
