Cameras ready? It’s time to take some great shots of comet C/2023 A3

If you want to try comet photography, tonight and the next few days are for you. Comet C/2023 A3 (Tsuchinshan-ATLAS) will be in our night sky shortly after sunset. Luckily, you probably have all the equipment you need on hand. No fancy tracking mounts, telescopes or filters are required. A DSLR is sufficient. Yes, stacking and tracking are great, but I’m trying to keep it simple here so you can just go outside and bring a good photo with you.

Find the comet

It won’t be too difficult. If you have clear weather, just look west, right where the sun just set. When you start to see some stars, you should see the comet just above the horizon. Here in Arizona, where I am, it will be in this position at 6:30 local time tonight.

For example, in Buffalo, New York, the situation will be slightly different. As you head north, the comet approaches the horizon. The further south you go, the higher it gets. There are some pretty good charts online to help you find your local perspective.

No one can be sure how bright Comet A3 will be. Some comets start out very bright and then decay. Some begin to dim and then quickly brighten. Don’t expect it to be as obvious as it is on the star maps.

Last night I took this picture about 30 minutes after sunset. It was difficult to see with the naked eye, and as the sky darkened, the comet sank lower, eventually dipping below the horizon.

As you can see, it wasn’t huge and was even fainter to see with the naked eye.

How to set up your camera

With most cameras you will need a longer lens than the wide angle lens I used on my Sony a7 IV. The image above was taken for 9 seconds at f/5.6 and ISO 1200 with a 20mm lens. You could increase the ISO slightly, but then noise plays a role.

When considering where to photograph, try to have a fairly clear horizon, but also think about some foreground elements like a lighthouse, a fence, trees or, in my case, a cactus.

I also cropped this image to compensate for my wide angle lens, which was a 20mm lens.

Focus is really important, and even though you can shoot wide open, your foreground will be out of focus and lack depth of field. f/5.6-f/11 works for me, but then you take long exposures to get enough light or increase the ISO. It is a celebration of compromises. With most lenses, star trails appear after 15 to 20 seconds, so try to stay below this value. Experiment and take pictures at different lengths so that when you get home to edit, you have some that work well.

It’s really difficult to judge what you’ve captured on your camera’s small screen in the dark. In the field, I could barely see the comet on my LCD screen, so try out different f-stops and exposure times and choose the best one when you get home.

Tonight (Sunday the 13th) is expected to be the best night for the comet as it makes its closest approach to Earth. Every night from here the comet gets higher but dimmer, and the moon gets brighter. It’s a lot to juggle to get the best image.

Forecasts suggest the comet will not be a suitable location for photography later this month. So if you’re interested and the weather is good, try it out as soon as possible – ideally this evening or tomorrow. Comet C/2023 A3 won’t be back for another 80,000 years, so now is the time.

Of course, there will be other comets that pass by every year, but this one is expected to be brighter than most we’ll see in about a decade.

Let us know how you get on and feel free to send us your C/2023 A3 images.