Astrophotography: How I shot Comet 46P from start to finish

If you have access to dark and clear skies, you should have a great opportunity to catch Comet 46P / Wirtanen leading up to it’s closest approach on December 16th. It’s great timing as there’s barely any moonlight to interfere with viewing the comet, too!

This is the second installment of my new series called The Process. Each time I’ll take you through the planning, shooting and processing of an image. On this post, I’ll also be sharing how to find the comet 46P, how I shot my images, and taking a special first look at the new Sigma 40mm f1.4 ART lens!

Let’s get going!

Planning: How to Find and Photograph Comet 46P

Almost as soon as it’s dark, the comet will be visible in the night sky. Comet 46P will continue to drift higher and become more visible as the week progresses, but that doesn’t mean you need to wait before heading out. This will be the brightest comet of 2018 and opportunities like this don’t come by too often so I suggest heading out as soon as you have clear skies!

I took a trip out to the Anza Borrego desert this past Saturday in hopes of catching a view of the comet and then the Delta IV rocket launch from Vandenberg AFB. Unfortunately, the launch was canceled with just 7.5 seconds remaining in the countdown, but we still had beautiful skies and a great first view of the comet.

Here are some behind the scenes photos and videos of what I took with me.

Gear for the Shoot

(Left Photo) Camera Body:  I brought both my Sony A7RII and my Nikon D800E with me. I planned on shooting primarily with the Sony and then maybe having the Nikon shoot a timelapse off to the side.

Lenses: 

Sigma 40mm f1.4 ART (A7RII)

Sigma 14mm f1.8 ART (A7RII)

Sigma 135mm f1.8 ART (A7RII)

Sigma 20mm 1.4 ART (Nikon)

Sigma 50mm 1.4 ART (Nikon)

(Right Photo) In addition to my camera gear, I also brought my Dell XPS 15 2-in-1. If I caught a photo of the launch, I was planning on making my way back to the car and getting it processed and posted as quickly as possible instead of driving home 2 hours and then just starting to work on the image. Being able to get a shot like that processed and posted right away is a huge advantage when photographing something that can be considered newsworthy or that might have a lot of people posting images.

Finding Comet 46P in the Sky

Currently, the comet can be seen in the East / South East skies shortly after sunset and then setting in the Western skies later in the night.

Early in the night, I looked toward the easy to find constellation Orion and the looked up and to the right a bit to locate the comet. As each night passes, the location will be a bit different than the night prior. Keep that in mind whether you’re planning on viewing or photographing.

To the unaided eye, it can be a little bit harder to find. It doesn’t have much color, but will have a small diffuse glow to it. In your images, the comet will have a brilliant green glow to it.

The chart to the right shows the location each night of the comet in the sky. If you’re still having a hard time, you can use apps like StarWalk, PhotoPills or Sky Guide to help you find the comet. If you’ve never used one of those apps before they’re a really great tool in the field. You can use the search function and enter the object you’re looking for in the sky. The apps highlight your searched object or you can simply hold your phone up to the sky and it will show a live chart of what you’re looking at in that direction!

Have your phone pointed right at the section of the sky the comet should be in, but you can still can’t find it? Try pointing your camera in the same spot and then taking a photo. The comet will show up as a green dot and should be pretty easy to see on the back of your camera if your skies are dark enough. If you’re still having trouble, try picking out bright star or constellation on one of the apps and then located it in your test image.

Once you know the location of the comet, the next thing we’ll need to do is get the shot! We’ll take a look at why I used the lens I did, my camera settings and my edit next!

Comet 46P Path
Chart via Sky and Telescope

How to Photograph Comet 46P / Wirtanen

Like all other objects in the night sky, they’re a bit easier to photograph when they’re located further from the horizon. Being further away from light pollution at the horizon helps whatever you’re photographing stand out in more and helps you capture more detail. Despite this, I really wanted to get a photograph of the comet and still have some sort of landscape and human element in the image. This would help make the image unique and stand out a bit from the images that focus just on the sky and the comet. Those will definitely be awesome and I hope to capture some as well, but for this first night out my primary focus would be a bit different.

I had one night out with the Sigma 40mm f1.4 ART prior to this and I was so blown away by the results that I knew I had to use it again to capture the comet. Aside from the quality of the lens, shooting at a slightly longer focal length would make the comet appear slightly larger in the sky.
My photo showing Kona, Rachel and I was taken at 6:42PM. Although it was visible earlier, you can see the light pollution on the bottom right part of my photo. I waited until the comet cleared this area by a decent distance and then found a hill to shoot from the bottom looking up at the three of us stargazing.  Setting things up like this helped the comet stand out while keeping a landscape element to the image.

Settings:

As referenced in the first post in The Process, there are a number of ways to capture a night sky image. Because this is somewhat of a news type event in the science field, I wanted to capture this in a single exposure. That meant all three of us would have to stand still for as long as the shutter was open. It took a few tries, but I think we did a pretty good job!

Here are the settings for the image below:

Sony A7RII

Sigma 40mm f1.4 ART

Exposure: 8 Seconds

ISO: 3200

40mm

As always, I had my camera set to capture images in RAW so I would be able to bring out the most detail possible while editing.  I used a remote shutter release to have the camera take the same exposure consecutively, similar to shooting star trails or a timelapse, so I’d have a few different photos to pick from. You end up with a bunch of very similar photos that you won’t use and some funny outtakes (see below), but it helps make sure you get the shot you’re after.
In other circumstances, you might approach a shot like this by taking a shorter exposure for the foreground and the people standing in the shot. After that, you can take a longer exposure for the sky that would pull more detail and blend the two images together in post. But, as I mentioned, this specific circumstance was about capturing the moment as true as possible.

You can see a few alternate takes and out takes below:

What Lens & Focal Length Should I Shoot the Comet With?

Depending on your desired results, you can really shoot the comet with a variety of focal lengths. Anything from an ultrawide 14mm to a telephoto 600mm will work! Keep in mind, the wider of a focal length that you pick, the smaller the comet will appear in the photo. This is exactly why I was excited to head out with the Sigma 40mm.

You’ll also want to make sure your lens has a fast aperture. Ideally, you’ll be shooting at f2.8 or faster. As noted above, I ended up shooting my images at f1.4.

A Closer Look: 

This section is a bit of a closer look at the comet and then a bit after a closer look at the image quality from the Sigma 40mm..

I was already a huge fan of shooting with the Sigma 35 and 50mm ART lenses, so I wasn’t too sure where this lens would fit. It’s a great focal length for panos, but the 35 and 50 are pretty killer lenses already. Well, all it took was one night of shooting and I was sold on this lens. Holy cow is this thing tack sharp from edge to edge. It’s early still, but this is already one of the most impressive lenses I’ve used to date.

First up, let’s take a closer look at the comet! The left is a 100% crop from the Sigma 40mm and the right is a square crop from the Sigma 135mm.

The comet might not have a large visible tail, but it’s still super exciting to see and photograph. Having that green glow show up on the back of your camera is really incredible.

During blue hour, I snapped a few photos of Kona and I on another hill. You can take a look at that image and then the image next to it to see a 100% crop of the corner from the Sigma 40mm f1.4 ART lens. Pretty impressive, if you ask me!

Processing:

While I wasn’t quite in the same rush that I would’ve been if I took photo of the Delta rocket launch, I still did all of my editing on my Dell XPS 15 2-in-1. To be honest, the edit of this was pretty straight forward. The biggest part of this edit was nailing the white balance that I wanted. This would help the comet show up green and stand out in the sky. Most of edits were done pretty quickly in Lightroom with one additional curves layer being added in Photoshop. With the curves layer, I added a bit more contrast to the overall image and then manually erased part of the mask in the foreground. It’s a very subtle effect that hopefully helps draw the eye in and up.

I ended up cropping the image just a small bit to as I felt it balanced the foreground a little better than my framing in the field. Aside from that, there wasn’t much left!

That’s about it! Hopefully in the coming days I’ll be sharing more images of the comet and from the new Sigma 40mm lens! This wasn’t originally the content I had planned for the second installment of The Process, but I hope it will help people get out and take great photos of the best comet of the year!

If you have any questions about the information above, feel free to reach out on Instagram or leave a comment below! As with each new post in The Process, I’ll be doing an Instagram live to answer questions and chat about everything a bit more! So, keep an eye out for that, too!

I’d love to hear what you think and if there are any images you’d like to know more about!

Thanks so much for checking this out! Special thanks to Sigma for getting me a copy of the 40mm to head out and shoot with! Good luck and clear skies!

Enjoy a special bonus photo of Kona : )

About the Author

Jack Fusco is a San Diego-based photographer and Sigma Photo Ambassador. He specializes in timelapse, landscape and astrophotography, and he went from being a touring musician to being a full-time photographer. You can see more of Jack’s work on his website, Facebook page, Instagram and Twitter. This article was also published here and shared with permission.