Capturing the Milky Way

Lights of the night
by
Kevin Ly

I lived in the city/suburbs for most of my life so this was the most amazing thing ever when I first took it. I can see stars! and even more than that, galaxies! I know, city boy problems. Anyway, here’s a breakdown of what I did. Obviously I never got a chance to practice this but I was able to get the images I wanted within a minute. How? Reading Reading Reading. I can not stress that enough. You can save yourself so much time by just studying the techniques behind different types of photography and getting an understanding of what is needed for each shot.

In this one, I first had to find the Milky Way (which is what I wanted to shoot). In dark areas, you can actually use your eyes and find a very dim stream of stars in the sky. I live on a college campus so there are street lamps everywhere. I stood a little in front of one along the cliff so the glare wouldn’t prevent me from seeing things. This goes for the camera too. Make sure the lights are BEHIND the camera so that the glare will be minimized. Adjust your viewing angle accordingly to reduce the glare/lens flare on the lens, and if you don’t know what that means, you’ll know when it becomes  a problem as you take the photos). It looks something like this.

Anyways, once you position yourself correctly, you need to understand what settings to set your camera. A lot of sites just list off the settings. I don’t think that teaches you a lot.

With Milky Way and deep space astrophotography, you need to understand that these are very dim specks of light. That means you need a very long shutter speed. With that comes the understanding of star trails. Stars in the sky move like the sun and everything else does because of Earth’s rotation. To make sure you don’t hold the shutter so long that the stars start to appear as if they’re moving and therefore create streaks, you will want to follow this rule. 500/x where x is your focal length. For wide angle lenses, I tend to go with 400/x because of distortion on the edges. The answer to this mini math problem will give you the maximum shutter speed you can use before star trails will appear. If you’re using a standard lens, say 18mm on a basic entry level DSLR, you know you can go up to 500/18 seconds as your shutter speed before your stars start to turn from dots into streaks.

Now that you understand your limits on shutter, the next steps are easy. You’re trying to capture pin points of light in a dark background, that means you’ll want to open up your aperture as wide as it will go unless you suffer from extreme aberration/color fringing (don’t worry about this too much if you’re just starting out).  So to remind you again, aperture is the f/ number, so the lower the number, the wider the aperture. Kit lenses will probably be f/3.5. Also, you’ll want to be zoomed all the way out because most likely you’ll want to get as much of the Milky Way as possible. Anything around or less than 18mm will be a good starting point. Shutter speed [check], Aperture [check], let’s talk about ISO now.

ISO is an interesting thing to consider because it’s probably where it gets a little subjective. This isn’t very intuitive but you will want to use a very HIGH ISO. Usually with long shutter speeds, you want it as low as possible but here since the light source is so dim, you want as much light as possible. Now the maximum acceptable ISO is determined by your camera and taste. On Nikons you can probably get away with 3200 while on Canons, I wouldn’t be comfortable going past 1600. This does not mean one camera is better than the other!

In the photograph I took, I actually used ISO 3200 but it’s a bit too noisy for my taste if I wanted to hit perfection. With long shutter night photography, you also have to consider the concept of hot spots. With any electronic device, when you have things running for long periods of time, they get hot. When sensors get hot, you get what are known as these hot spots or hot pixels with green and red speckling OTHER than that noise that high ISOs create. Some cameras have “High ISO noise reduction” I haven’t personally tried it yet but I think it would certainly help to have that enabled. It basically takes a darker frame after your original shot to cancel out the pixels that are causing problems.

With regards to focus, because that’s always an issue at night, I just focus on something lit up in the distance or just rely on infinity to actually be infinity (even though i know it’s not. Lenses are always infinite a little before the ring stops). Point is, focus using the auto focus and then SWITCH TO MANUAL FOCUS before repositioning to compose your shot.

I think we covered all the settings, to summarize it, I shot this photo at 8mm, for 45 seconds, ISO 3200. I did a bit of post processing to reduce on noise and color correct. The orange street lights cast a very warm glow on everything. We can discuss processing in a later post.

Other equipment that you should use if available: A tripod, remote cable release (wired or wireless) to help you trigger your shutter without pushing the button and introducing shake. If not, you can use a 2 second or 10 second timer to press the button and let the camera settle before it triggers the release. Also spare batteries won’t hurt. Long exposures take up a lot of power so you won’t get nearly as many shots on one charge.

Once you captured your photos, see how I process them here in a follow up video post.