Astrophotography Learnings

Updated: Apr 2

Astrophotography has always been a huge interest for me with regards to sub-types of landscape photography. Although it tends to be a little more difficult and time consuming to pull off as effectively as some of the other photography that you can see scrolling through my portfolio. If you follow my Instagram account, you might have seen a couple of my early attempts at astrophotography already. These pictures for the most part are nothing special, outside of the sky being amazingly beautiful on a clear night.


These pictures worked okay for a few Instagram posts on social media, but for most other applications the images are not adequate to be used. Most of the learnings for me with this type of landscape photography have come down to three things: gear, location, and weather. Processing can also be more difficult for the stacking of images, but I will save discussion of this subject for another blog post. While I do have a newer photo in my saga to master this form of photography, I still do not have anything outstanding to show. You will just have to wait for the next installment of an astrophotography post later this Summer for that!


25 seconds at F/1.8, ISO 5000, 24mm (NIKKOR Z 24mm F/1.8 S): 6 Image Stack

Now, let us dive into the issues I have had and some remedies that might help others attempting to get into this type of photography. Starting off with the issues that are induced by the type of gear that I have been using up to this point.


GEAR

NIKKOR Z 24mm F/1.8 S and NIKKOR Z 24-70mm F/4 S Mirrorless Lenses

The lens pictured on the right above was the first lens I had for my camera. The kit lens that comes with the Nikon Z6 and Z7 mirrorless cameras. This lens is honestly quite impressive, and if you are curious to learn a bit more about it you can check out my blog post comparing it to the Nikkor 24-70mm F/2.8, which is the sharper, professional version of the lens. However, without additional equipment it cannot do a particularly good job in low light conditions due to the F/4.0 aperture size. You can capture stars with this lens using a few different tricks, but it is more difficult to get the stunning shots and reduce image noise.


This difficulty arises due to the stars in the night sky being constantly in motion. When things get dark, one way to get more light onto the sensor is to increase the exposure time but if your exposure time is too long then you begin to get star trails. Instead of your stars looking like stationary bright dots, they look like little lines. The common rule of thumb for the field is the 500 rule. You divide the focal length that you are shooting at by the number 500. This gives you the approximate max exposure time you should use to avoid star trails in your photos. This rule is not 100% accurate but is fairly accurate to use for general purposes.


With this in mind, this limits my 24-70mm lenses to exposure times of about 21 seconds. This can capture a good amount of light but leaves out some of the details of the milky way, if you are shooting this. Barring exposure length and aperture settings, this means that you must boost your ISO up to high levels which introduces a large amount of noise. As my beach milky way shot shown above is at an ISO of 5000.


This means that the characteristics that effect astrophotography the most in a general sense are how low the aperture on your lens can go, and what focal length you are shooting at. Specifically, that wide angle shots of the sky tend to be common in an attempt to increase the exposure time that you can use. Which led me to make my original purchase of the NIKKOR Z 24mm F/1.8 S lens in an effort to get better low light performance from the better aperture range. At the time, Nikon had not released their 14-24mm lens which I might have gone for instead.


30 seconds at F/1.8, ISO 4000, 24mm (NIKKOR Z 24mm F/1.8 S): 8 Image Stack

With the new lens, I was able to get better clarity and slightly less noise out of the pictures. But I kept hitting the issue of the exposure time that I wanted to use to try and offset the need for higher ISO settings. In the example above I used 30 second exposures on the 24mm lens with ISO of 4000. There is clearly less noise in the stars and more detail in the milky way, but the star trailing becomes distracting at this point making for a less than ideal image.


This brings me to the final piece of equipment that I obtained in my quest to figure out astrophotography, the star tracker. The one I purchased was the iOptron Star Tracker Pro. The idea behind a star tracker simply stated is that once it is aligned with a particular star, Polaris, you can then take long exposures of several minutes without star trails being an issue. Honestly, this one piece of equipment makes most lenses viable options for astrophotography. It has been a learning process getting to this point, but it you are also interested in astrophotography I would recommend looking at getting a star tracker over buying a new lens. It is probably cheaper, and it works better once set up properly.