Astrophotography – Seeing the Light in the Darkest Places

In Astrophotography, Learning Center, Tutorials by jfischer2 Comments

I remember vividly the wonder, and the frustration, in trying to capture my first astrophotography photographs.  I was standing on the edge of the road in the middle of Yellowstone National Park, taking in the arch of the milky way as it reached overhead.  It was one of the first times in my adult life, or ever that I could recall, that I was able to see the band of stars that make up our galaxy from the general star field stretching across the sky.  The problem was, I knew little about how to capture the faint light filtering in from the dark skies above.  I knew I needed a fast lens, I knew I needed a high ISO, and I knew that the longer the shutter length the more stars would start to blur.  But beyond those general tips, I had little real knowledge at my finger tips to make the most of my time under the dark clear skies of Yellowstone.  That experience, and the photos I came home with, inspired me to dive much deeper into the subject of dark sky photography in the pursuit of ever more amazing images.  My hope is to ignite a little bit of that wonder in you as well – and provide a few tools so your next outing might result in better shots than my first.

Equipment

Back in Yellowstone I had my trusty Canon 60D, Tokina 11-16mm f/2.8 ultra-wide lens, and a small travel tripod.  While lens is one of the better options available to crop body camera owners for astrophotography, unfortunately the 60D, even at the time, wasn’t the best at high ISO and even in a moderate breeze my little travel tripod wasn’t going to hold the setup still enough for really sharp captures over 30 seconds.

Rule 1 – the 600 Rule, or the 500 Rule, depending on how picky you are.  Divide 600 (or 500) and divide it by your effective focal length.  This is the time, in seconds, you have to capture all the light you can before stars begin to blur.  Crop body users, don’t forget to multiply in your crop factor of 1.5 (Nikon) or 1.6 (Canon) to get your effective focal length.  Your 11mm Tokina is really 17.6mm, no cheating.    Full frame users, you can just take the number off the side of your lens.

Camera Body

Any camera that can be set to manual exposure with a shutter speed of up to 30 seconds can be used for astrophotography.  My 60D proved that, and I’m sure there are astrophotography shots taken with even older entry level cameras.  Given the option however, you want the best low-light / high ISO performance you can get your hands on.  Full Frame camera bodies are usually the best at this, and often those with slightly lower Mega Pixel counts often fare better as well.  The lower pixel density on the sensor normally equates to better high ISO performance by allowing the photon ‘cells’ (the individual pixels) to be bigger.  The bigger these cells less susceptible to variations readings due to camera voltage, heat, etc – ie: noise.  Full frame cameras such as the Canon 6D which I shoot with a great option, however the truth is, most digital camera bodies produced in the last few years have ISO performance well within reasonable ranges for capturing stunning night skies.  Depending on your lens choices, ISO requirements will be between 800 and 3200, possibly up to 6400 for the Milky Way.  Star Trails can be captured at ISO levels at half of that depending on the desired effect.

Lenses

Fast wins the race.  And when you’re racing against stars, you need all the speed you can get.  A lens with a maximum aperture of F/4 is barely adequate for most situations without resorting to extreme ISO ranges of 6400+ for Milky Way shots. f/2.8 or better should be your goal when selecting astrophotography lenses.  Given two lenses with the same focal length, an aperture of f/2.8 gathers twice as much light as f/4, meaning you can either half your shutter speed (500 rule), or half your ISO (cleaner image), for the same brightness of capture.  When working in the world of Astrophotography, you have to take both max aperture and focal length into account, don’t be fooled into thinking a 2.8 lens is a 2.8 lens regardless of focal length.  That holds under the sun lit skies, but we’ve left that world behind at sunset.  With a little post processing trickery, even something like the 50 f/1.4 isn’t completely useless under the night sky – just remember that 500 rule!  Striking somewhat of a happy medium, the featured photo at the top of this article was shot on my Canon 6D and Canon EF 28mm f/1.8 @ f/2.0.  I was able to use a shorter shutter speed and lower ISO than had I shot the same frame with the EF 16-35mm f/4 at it’s widest focal length.

Tripod & Accessories

Almost any tripod is better than no tripod.  Shutter speeds are going to be in tens of seconds, trust me, even before your second energy drink to get you through the night, you’re not going to hand-hold your camera, and a book or two stacked on your car’s roof isn’t much better.  When looking at tripods for astrophotography, the bigger and heavier the better – as long as you’re willing to carry it to your location.  I shot my first several night sky sets on my little MeFoto RoadTrip, a small lightweight travel tripod.  Not bad when the air is dead still, and if you only extend the first few leg segments, it’s even serviceable in a light breeze.  Since then, as I became increasingly serious about shooting the night sky, I raided the photography funds for a bigger and more stable Induro 3-series tripod that makes the RoadTrip look like a toothpick.  Don’t overlook the importance of the ball-head on top of the tripod either.  A rock steady base with a head that lets the camera move doesn’t do you any good.  I also pack a beanbag weight and paracord to add additional weight if needed to help steady the tripod when I think the situation calls for it.  The cord is so that I can rest the weight on the ground to keep it from swinging below the tripod.  A giant pendulum isn’t very conductive to steady shots either.

MeFoto RoadTrip vs Induro CLT304L – fewer leg segments also mean thicker final legs on the new Induro.

Another useful item to have on hand is a remote shutter release (though a 2 or 10 second self timer can be used and some will argue is even better).  I use the wired type which you don’t have to worry about losing in the dark, and I keep it draped over the top of the camera body to keep it from swinging in the wind as much as possible.

A flashlight and/or headlamp is also going to be quite necessary at some point during the night, so be sure to know where they are and that they have fresh batteries before you need them.  Models with a red light will preserve your night vision much more than the white pure light – something other photographers in the area will appreciate, and will help you keep an eye on the location of the milky way over head as the night progresses.

Now which of these switches is manual focus?

Where to Shoot

There’s a very simple answer to this – as far away from any source of light pollution as possible – and this means cities and towns.  The darker the skies the more stars you, and your camera, will be able to see.  There are a number of nationally and internationally recognized dark sky sites around the world that are publicly accessible.  Beyond those locations, your best course of action will be to google ‘Dark Sky Sites’ and use one of the online resources such as Dark Sky Finder (jshine.net).  Many national parks are good bets, don’t discount state parks as well, though some you might have to be creative with the direction of your shots to avoid the air glow of near by towns.

When to Shoot

In the northern hemisphere, there are only certain times of the year that the Milky Way is visible above the horizon while the sun is not.  And throughout this period of the year which covers April through early October, the time which the Milky Way rises and sets changes.  Early in the year there’s no use being out at 11pm trying to shoot the milky way, it won’t rise above the horizon till well after midnight.  The moon phase as well as it’s rise and set times are also something to consider.  Depending on the look you want, you might want to wait till the new moon, or first/last quarter.  Full moon is generally a bad choice for Milky Way shooting for the same reason you want to get away from the city.  Having a full moon sitting square in the middle of the Milky Way core is certainly not something you want to discover after driving 4+ hrs to the middle of no where.

Weather

When your primary goal is to capture light coming in from distant stars, an overcast rainy night isn’t going to work very well.  However, don’t cancel your plans just because there’s a few clouds in the forecast.  Especially if those clouds might be a few pop up thunderstorms that will be there and gone within an hour or two.  First, the short rain shower will wash a lot of the dust and such out of the air, making for cleaner air for that star light to travel through.  Second, some of the most amazing night sky photos I’ve ever seen contain sky elements beyond just the stars.  Clouds will mess with any plans to shoot star trails however, leaving big gaps in your star trails where the clouds pass by, streaking foggy effects and pin point stars just don’t mix.  Alternative plan – shoot a time lapse!  But that’s a topic for another article.

Weather, especially in places such as Arizona, Utah, Texas, well, really just about anywhere, can change rapidly.  There are good cellphone apps that can help you keep on top of what the weather will likely do over the course of the evening and into the morning hours. I’ve called it a total loss and went home early more than once and woke up the next day to see that the skies had cleared only a few hours after I pointed my truck for home.  This happened once in New Zealand, and I didn’t have another chance to shoot the night sky from down there the rest of the trip.  Don’t let this happen to you!

Clouds plus a little light adds an extra element to the sky

On Location

The single biggest nugget of wisdom I’ve learned about astrophotography is that the sky is NOT your subject.  Keep that in mind and your photos will be exponentially better almost immediately.  It was certainly one of those pieces of knowledge I didn’t know going into my first attempt back in Yellowstone.  It was still not quite obvious to me when I tried again on the side of Mt. Hood in Oregon a year later.  Think of the sky as the icing on the cake.  While pretty, and quite necessary to the overall image, it should not be the subject.  You need an anchor.  You need the cake.  Finding good cake in the dark is difficult.  Research before you get on location or at least recon before nightfall is important.  Else, bring a really big flashlight and hope there aren’t other photographers in the area that you’ll be disturbing with its use!

Subject? I don’t a subject, I’ve got MILKY WAY! (My first attempt at Yellowstone)

Once the sky is dark and the stars come out, if you are careful about not using white light flashlights, your eyes should soon adjust to take in enough light to see the faint arch of the Milky Way over head.  If you’ve done your recon and know what subjects you want to shoot, now it’s time to find the composition that showcases both your subject, and that beautiful night sky.  All of your composition rules for landscapes that apply during the day still apply here.  Get your tripod and camera setup and start dialing in your shot.

Top Tip #1: Max your ISO, shoot maximum aperture for short shutter speeds while trying different compositions or dialing in the perfect angle.  Waiting 15-30 seconds if you’re not 100% sure it’s the shot you want is wasting a lot of time.  Since it’s difficult to see exactly what you’re going to get through the new finder or even in Live View, don’t be afraid to take some test shots at extreme settings.

Once I’m happy with the composition, I usually try to stay at either ISO 1600 or ISO 3200 on my 6D, adjusting exposure time as low as possible for the lens and exposure needed.

Top Tip #2: It’s often easier to reduce noise from a well exposed photo at a higher ISO than one that’s been boosted in post.  If ISO 1600 is too dark to get the detail you want out of the sky, don’t think ‘I’ll just fix it in post’, take the shot at ISO 3200 as well, more often than not you’ll be thankful you did.  Some of the latest and greatest Sony sensors are not as sensitive to this, enabling them to recover much more shadow detail in post processing, but the age old adage of getting it right in camera still holds.

Foreground Lighting

So I just dropped the bombshell on you that the sky isn’t your subject.  Great, now how do you get your subject to be visible in the dark.  Two options here, either let the moon do the work for you, or light it up yourself with your flashlight, flash, etc.  If you’re lucky enough to be shooting when the moon is over your back shoulder, you can let it light up great expanses of the ground before you in a beautiful soft even light.  Great for when you’re standing on the side of a mountain with an alpine lake stretched out in front of you that you’d never light with any number of flashlights.  If your subject is smaller, such as a tree, a single building, or even a small clump of cactus, you can use your own lighting tools to splash light on just what you want lit to make sure IT is the subject.

Get creative with your lighting.  As long as you’re not setting fire to things that don’t belong to you or otherwise defacing or destroying them, there is no rules to how to light your subject.  Finding the balance of light vs sky exposure takes some trial and error – sometimes a lot of error.  If you’re willing to put in the time in Photoshop or Gimp later, you can also blend multiple trials to mask out the errors till you get the look you ultimately want.

4 images were blended to get the sky and the foreground just right.

Post Processing

I’m not going to lie, you’re going to need to spend some time in front of your computer back home to get the most out of your Milky Way photos.  Even more so if you also decided to dive into the world of star-trails which I hope to cover more completely down the road in another article.  At the very least you’re going to want Lightroom or another photo editing software that gives you more than general exposure and saturation controls, especially since you were shooting RAW images… right!?!  For a simple Lightroom edit, here’s where I would start:

  1. Reduce Temp to the cool and increase Tint towards the Magenta until the hue of the sky is to your liking but isn’t altering the foreground so much it’s unrealistic.  The Gradient and Adjustment Brush can help fix foreground White Balance vs sky.
  2. Leave Exposure and Contrast alone (for now)
  3. Work with White and Blacks slider first to bring out star and sky contrast
  4. Boost Clarity (10-30) and Vibrance (to taste)
  5. Work with the Tone Curve to fine tune contrast to taste.
  6. Lens Corrections – ensure Remove Chromatic Aberration is enabled, if you choose to enable Profile Corrections, you may look at reducing the effect of the Vignetting under the Profile tab as it can turn the corners too pale.
  7. Detail – Don’t be afraid of the Noise Reduction slider in Lightroom.  But also ensure you’re using the Masking slider in Sharpening so you’re not effecting the dark sky regions with additional noise than necessary.  Other plug-ins such as Nik and Topaz also have great noise reduction elements that can help clean your image with minimal detail loss.

astro1_bna

Completed edit compared to the original RAW file as imported into Lightroom

Diving into the world of Astrophotography can be a bit intimidating, but it doesn’t have to be completely overwhelming either.  Don’t be discouraged if your first images look more akin to my early Yellowstone shots than my more recent examples.  Working in the pitch black is one of the more challenging places for photography work – a medium that in its purest form is simply capturing light.  While you can read all the articles on the web, look at all the examples of shots you can find on 500px, Flickr, Facebook and beyond, there’s simply no substitute for getting out to a dark spot of sky and getting some experience under your belt.  My hope is that this article has provided a few steps forward, a few tools and tips to aid you as you in your own journey into the great darkness – that turns out really isn’t all that dark at all.  The night sky is wondrous, awe inspiring and magical – I hope you find the inspiration to go explore it.

Further Reading

Haven’t gotten enough Astrophogoraphy knowledge download for one day?  Or want a few ideas for future reading.  Checking these links here on JonPFischer.com and beyond!

Comments

  1. jp

    JUst found your site off dfw photo story link , WOW man o man how I Wish I could walk away with a huge score photo like yours ,,trying so hard not to get worked up on the cycle of disapointment ,,try try again .Thanks for your work .

  2. Pingback: Astrophotography Lenses – Beyond the f-number | Fischer Photography

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