Back when I was in school teachers would always scare me with stories of how my exploits would end up in my permanent record. I believe this is it! – Geoff Fox
There are days like this scattered through April and May. There are more in September, but those don’t count because they’re just a reminder summer’s gone, winter’s next.
After a high around 70° we’ve settled back to near 50°. The air is calm. The sky is clear. The dew point is in the low 40°s. The weather is perfect.
Connecticut doesn’t get this type of loveliness often enough. There are days like this scattered through April and May. There are more in September, but those don’t count because they’re just a reminder summer’s gone, winter’s next.
How do you celebrate a day like today? What do you do? The answer for me was to take a photo to celebrate the night.
This shot is taken with my Sigma 30mm f/1.4 lens. It’s a 10 second exposure at ISO 200.
I don’t use this lens enough! For work like this it’s extremely difficult to focus. There’s no “auto” when it’s pitch black. Unfortunately, infinity in reality doesn’t line up with the ∞ mark on the lens.
The lens is super fast. You see a lot more in this photo than I saw while standing there (in the dark hoping there were no animals stalking me).
To me it says everything about what this evening is.
There are no clouds nor is there wind. Considering I’m in the burbs tonight was as good as it gets.
I want to take shots of the nighttime sky, but I hate being outside at night! Tonight was too beautiful to miss. The Moon set early leaving the sky overhead quite dark.
There are no clouds nor is there wind. Considering I’m in the burbs tonight was as good as it gets.
I went up stairs plucked my 8mm lens and threw it on my Canon 7D. This lens is the photography equivalent of the fisheyes used on apartment door peepholes.
The lens is fully manual so I set it around F/5.6 with ISO 6400 and the shutter open 30 seconds. If I’d held the shot much longer the movement of the Earth seen as ‘streaky stars’ would have been evident.
I need to plan a night and go somewhere really dark. There are more shots to be taken.
I know it’s time to go when she climbs onto my lap. That’s her signal. She is purposeful and resolute. It’s time!
Thanks to Doppler I’ve started to get a great appreciation of night. I know it’s time to go when she climbs onto my lap. That’s her signal. She is purposeful and resolute. It’s time!
She doesn’t particularly like the cold and acts accordingly. She is efficient.
I put on my heavy jacket, picked up the leash (with bag dispenser) and an immense flashlight and headed out. Doppler walked to my right. That’s her preferred side.
She’s small, but the front steps pose no challenge to her.
Cold tonight and crisp. There were thin clouds. The Moon was low in the east–just rising.
We walked on the lightly frozen grass. It gave grudgingly with each step.
There are noises from the woods. Not my favorite thing. We’ve got critters of all types around. They want to avoid me. Right back atcha.
The stars are beautiful. Some nights before the Moon rises or after it sets the sky turns a very deep inky blue. The longer you’re out the more stars there are!
Even when the weather’s been bad it’s obvious Doppler and I have a mutual interest. Good doggie.
Meanwhile the Earth is spinning on its axis. Like the rotating restaurant on the top of a cheesy hotel we are constantly pointing in a different direction. That creates a photographic problem and opens a photographic opportunity!
A few nights ago I pulled “Clicky” out and shot the night sky. My intention was to produce a time lapse as the stars rotated by (at the bottom of this entry).
As I showed the video one thing became obvious. Many of those who saw it didn’t realize they’d see that effect from a camera in a fixed position. We’ve become out-of-touch with the nighttime sky which no longer is as visible nor has the importance it did to our great grandparents.
Stars are very, very far from us. The closest star (other than our own Sun) is Proxima Centauri which is about 25,260,733,353,600 miles away (that’s 25+ trillion miles)! Others in the visible sky are thousands or even millions of times more distant. That keeps our view of stars reasonably constant.
Meanwhile the Earth is spinning on its axis. Like the rotating restaurant on the top of a cheesy hotel we are constantly pointing in a different direction. That creates a photographic problem and opens a photographic opportunity!
The opportunity is time lapse. What my little movie shows isn’t stars moving, but the effect of the Earth rotating¹. Aiming at any single point in the sky reveals stars passing by. They’ll return to about the same point 24 hours later.
The photographic problem is the same one faced any time you try to photograph something in motion: blur!
Because stars are dim the only way to photograph them is to keep the shutter open a long time and allow more photons to hit the camera’s sensor. The longer the shutter is open the farther those stars move. The result is streaks across the sky, not points of starry light.
Sophisticated astronomers (aka – not me) solve this problem with clock drives. Their telescopes and cameras move in exactly the opposite direction as the Earth. The effect is to hold the stars still.
There are simple mechanical devices that do exactly the same thing. I’ve got a little wooden wedge with a hand turned screw which allows my camera to take long star exposures with impunity.
Nowadays the easiest way to eliminate the blur is with a software assist.
When I shot my time lapse I took over 400 images one-after-the-other. Each was a single second’s look at the sky. Using a program called DeepSkyStacker I combined those images and restacked them eliminating the effect of Earth’s rotation.
As a bonus DeepSkyStacker looks at specially shot blank frames to understand my specific camera’s weaknesses and counteract them!
The resulting photo is the equivalent of an eight minute plus exposure–though digitally made superior.
I’ve taken a small piece of it an placed it at full resolution at the top of this entry. Just below it is the full frame (though not at full resolution). These shots, compilations of over 400 separate photos, show stars I couldn’t see with my naked eye.
It’s all very heady stuff and amazing to me. It’s not just that these techniques are available, it’s that they’re available to anyone for free and easily used with cameras a lot less sophisticated than mine.
¹ – Here’s re-tweaked version of my time lapse nighttime sky movie from a few night ago.
I pointed the camera toward the sky. A few stars were bright enough to use to focus. This was going to be a 100% manually set shoot.
My intention was to go out and view Comet McNaught last night. For a variety of reasons (including disappointing results from others) I stayed home. Still, stars and sky were on my mind!
I pulled out the camera (aka Clicky), threw on my 70-200mm f/2.8 lens (Thanks again Santa… how do you know?), picked up my tripod and intervalometer and headed out to the deck. After yesterday’s hellish storms it was good to be outside on a clear, nicely breezy, warm night. The oppressive humidity of the afternoon was long gone.
I pointed the camera toward the sky. A few stars were bright enough to use to focus. This was going to be a 100% manually set shoot.
I pulled back the zoom from its maximum focal length down to 100mm then snapped off a shot at f/2.8, 1 second, iso 1600. I needed to make sure the camera would capture something. It did. Zooming in showed the picture was pretty sharp.
The one second shutter was a critical number. As you’ll see in the animation the stars move across the sky. Hold the shutter open too long and the stars will be streaky blurs.
My last step was setting the intervalometer. I set it to six second intervals which gave me ten shots a minute.
I let it run for around 45 minutes.
The finished product was run through Sony Vegas 9, a video editor. Levels were adjusted, but there’s an interesting conflict between stars and noise if you bring the gain up too much. That’s a technique probably only learned through trial and error.
Originally this was uploaded to Youtube. It was compressed so much the stars virtually disappeared. This method is a little better, but I’ll probably work on another method this weekend.
