Nine Days Across the Outback: Day One

I landed in the Outback at a resort town called Ayer's Rock. Coming off the plain, I was assaulted by red in every direction. I picked up a tiny handful of the stuff, and it was thin and powdery (the better to get on your sensor, naturally). We got picked up at a hotel by an exotic four wheel drive style vehicle, and drove nearby to a place called Kata Tjuta, where big red lumps of sandstone rise out of the plains. They were impressive, but I was bedeviled by a flat, overcast sky. Great for taking photos of people, less so for large natural rock formations that I wanted to see some pop in. We also stopped at sunset Uluru, which is why there is an Ayer's Rock resort in the first place, but the sky was mush -- not a single bit of color in the gray afternoon. More on that tomorrow though, because Uluru deserves its own day.

That night, we made our way to a camp, where we had to chase off dingos, which made off with a woman's pringles (don't ask). As our dinner was cooking, I looked up and noticed that the moon had vanished by some clouds on the horizon. Directly above me was a patch of clear sky, and the stars spread across it like diamond dust. Where we were in the Outback, we were really half a continent away from everything. No light pollution in any direction -- I think you'd have go out on a ship in the middle of the Pacific (or maybe the Himalayas?) to get a clearer sky.

Now, I don't know a lot about taking pictures of stars, and I knew even less, trapped in the Outback away from my precious, precious internet, and even miles from any cell signal.

My co-worker Tim explained this to our young tour guide, who was mystified that we would be going through information withdrawal.

"Imagine the closest you can come to being a demigod. Everything is at your fingertips: Press a button, stuff arrives at your doorstep. Get lost? Look up a map on your phone. Don't know something? Google for it. Now, imagine if all that went away."

So, I knew a few things:

• Stars are really dim
• But if you have too long of an exposure, you get star trails (which you may want)
• Bump up your ISO too much, and the noises overwhelms your stars
• I wanted a big, expansive vista of stars
• But, I knew I'd need more than just stars -- either to frame the picture, or give it context.
  

I figured that meant I wanted something with a reasonable focal range (probably south of 70mm), something that opened very wide (at least f/2), and good quality.

So, I popped on my Nikkor 50mm f/1.4, put the camera on my tripod, and pointed it at the sky. I was getting what I thought was a very reasonable result around f/2 and 5 seconds:


Now, what went wrong here?

For one, I got a little paranoid about those stars moving, so I kept trying to get my exposure down. As a result of this, I kept it pretty close to wide open (f/2). This has a number of deleterious results on my photo. For one (and more obviously), you can see that the trees in the foreground are blurred, since I've knocked the branches out of my depth of field. Relatively a minor problem though, and maybe I can convince people that I, uh, did that for artistic effect.

More troubling is what you see in the corners of the image:


Whats' going on with the stars? Why aren't they points of light? It's not like I've exposed for too long -- they're little wedges.

This is a type of lens aberration that occurs when you have pinpoint sources of light off the main axis called Coma Aberration. Lenses which want to minimize coma aberration have an aspherical element, which generally does the job. The good news is there are new, high quality lenses out there with aspherical elements which can be had for relatively cheaply -- like the new Sigma 50mm f/1.4. The bad news is, this was not the lens I had on my camera. I had my Nikkor 50mm.

While it has many virtues, resistant to aberrations is not one of them. It's razor sharp by f/2.8. Very contrasty. Images look *good* with this thing. It's tiny -- so small it can even go in a jeans or shorts pocket. So small that if a team of secret service agents is limiting by lens length cameras that can go into a Barack Obama fundraiser, they won't bat an eye at your ginormous SLR when you've got this little baby on the camera.

However, in this case, I sort of hosed myself. The only thing I could have done to help myself out here was to stop down -- probably to at least f/4, or maybe even higher. Now, if you remember from up above, I was also concerned about the exposure getting too long, so the stars would get motion blur. Turns out, most people who are serious about taking photos of stars without trails put their camera on telescopes with motors that track stars in the sky. Who knew?

And me, I didn't have much time to fool around after this shot -- dinner was ready, and by the time I came back out, the moon was shining brightly again, and I'd lost this shot. Still, I learned something after I brought this picture back from the wilds, and hopefully now you have too.

If you're like to check out my other first day Outback photos, you can find them all here.