Thursday, October 14, 2010

Pic(k) of the week 41: The world is turning!

I'm in the middle of editing 2000 images of a recent trip to Namibia. At times I find it challenging to remain focused on editing a large batch of images like these. Taking breaks and not rushing seems to be the key! 

Perfect time to write a post on something I tried for the first time, while in Namibia. We had finished dinner at a remote camping spot just under 2000 m altitude. The nearest city with streetlights was over 200 km or a 5 hour drive away. The air was cold and the moonless sky pitch dark and crystal clear. A perfect location for star trail photography! 
I had a vague idea how this was done, but it quickly became obvious that there would be some guessing. A quick online search would have helped a lot, but needless to say internet was not available at this remote location! 

I started setting up my Nikon D700 with the 14-24mm 2.8 lens on my sturdy Gitzo tripod and connected the remote cable release. Pressing the shutter manually should be avoided because of the introduction of camera shake. Most cameras limit the normal exposure time to a maximum of 30 sec. Using Bulb mode is the only way around it.

In the Northern hemisphere one needs to point the camera to Polaris (the Northern star) in order to a have a good sense of motion. Being down under in the Southern hemisphere, I initially wasn't sure... It turned out (by trial and error) that one needs to center on the Southern star. The only problem is that there is no Southern star visible by the naked eye. The free iPhone app, "Stars" together my compass on my iphone saved the day.
Pic(k) of the week 41: The world is turning!
Namib Grens camp, Namibia
The lighter tones on the right hand side of the image are part of the Milky Way Galaxy. I initially tried a 15 min exposure followed by a 20 min one at f 5.6 aperture. It turned out too dark and found that 30 min was going to be the sweet-spot. I first found it a challenge to focus because of the lack of contrast in the very dark sky. It turned out that leaving the focus on manual and infinity would do the job just fine.


Ideally, I should have opened the aperture up to f 4.0 or even f 2.8 to increase the exposure even more. Exposing the sensor during longer times (up to 1 hour) would have achieved the same but I was running out of time already. One does not want to increase the ISO above the minimum value because of noise issues in the shadows. Even with an excellent high ISO performer like the Nikon D700. Switching the in-camera noise reduction function ON, drastically helps reducing noise but also doubles time between two exposures. Taking a 30 min exposure, the camera basically needs another 30 mins to do the noise reduction. 


I also experimented a little with "painting with light". Using a normal flashlight I wanted to make the tree in the foreground stand out a bit more.
An early morning wake-up and temperatures reducing below 10 C, made me call it a night and climb up into the 4x4 roof-top tent. I definitively want to experiment a bit more with this, but finding a place as dark as this one won't be easy... 


Image details:
Nikon D700 with Nikkor 14-24mm 2.8
ISO 200, f5.6, 14mm, 1732sec (just below 30min)
RAW LR3 processing

I do hope to start uploading more images of our Namibia photo-aventure in the coming days.

Take that lens cap off,
BJORN

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