Latest Post - Category: Photography
Rain spider nest
Sun, 21 Feb 2010 18:04:02 +0200
Just after we moved into our house in early February, Esther noticed a strange looking spider nest among the flowers at the front of the house. It was a ratty bunch of leaves, wrapped in silken thread, suspended in the air by more silken threads holding it to the plants. At the bottom of the nest was a very large brown spider, probably 3-4 cm long.
Female rain spider on nest.
I photographed it, and tried to get closer, but as soon as I moved a nearby plant stem, the spider let go and dropped to the ground. On Saturday (Feb 20) I went to Walter Sissulu National Botanical Garden, and was sitting in the bird blind when a fellow photographer saw my macro lens and suggested I go photograph the strange spider nest nearby. She described it, and I knew it was the same as the one at my house, so I followed her to the nest and managed to get a couple of photographs before the spider again dropped to the ground and disappeared.
Fortunately, I have an Android phone with an Internet connection, so a bit of Googling quickly revealed it to be a rain spider nest. I went back to try to get a closer shot, and the spider had returned to the nest, but as soon as I tried to get closer, it dropped to the ground again.
Female rain spider on nest at Walter Sissulu National Botanical Garden.
Wikipedia has the following to say:
Coming back from grocery shopping today (Sunday, Feb 21), as I was entering the driveway, I stopped to take a look at the nest. I had last looked on Saturday, the female spider has still been at the nest then, but the nest was looking darker inside. Today, the bottom of the nest was crowded with the dark shapes of young spiders, densely packed outside the nest.
Young rain spiders at bottom of nest.
Rain spiders are perfectly harmless to people, though in ignorance we tend to fear them because of their large size and their tendency to walk fast and try to act fierce when confronted. These spiders, like most others, actually prey on insects so are beneficial to have around. The best strategy to adopt is to ignore them or, if they are in your house, to catch them in a container and put them outside. It would be sad if these magnificant creatures were harmed due to human ignorance. I hope that many of those that just hatched outside my house survive and go on to make their own nests. They are fascinating to observe, and wonderful for showing children the amazing way of the natural world.
Closer view of young rain spiders.
Someone made a video of a rain spider in his house, and as you can see they are quite big.
Please remember they are harmeless. Completely. Promise.
spiders insects macro
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Previous Posts
Time lapse of huge cloud over Johannesburg
Sun, 21 Feb 2010 18:02:33 +0200
This time lapse video was made according to the method I described in my last post (see below).
Let me know if you make your own based on these methods.
timelapse clouds
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Time lapse photography with GNU/Linux
Sun, 14 Feb 2010 12:17:50 +0200
If you read this blog from time to time, you may have noticed that I am nuts about photography. I have been since my mother saved up, sacrificing because we were not well off, to buy me a Minolta camera when I was in high school. Since I am just as nuts about GNU/Linux, an article in a magazine sparked me to see if I could combine the two. Having recently bought a house atop a hill overlooking the city of Johannesburg, the spectacular views and ever changing summer skyscape presents an opportunity to experiment with time lapse photography.
gPhoto is a set of software applications and libraries for use in digital photography. The applications support retrieving of images from camera devices, but more interestingly also remote controlled configuration and capture. Of course, what functionality is available for a given camera depends on whether the camera supports particular features and whether the developers have been able to reverse engineer the camera's commands. It supports more than 1100 cameras to download photos from, but for actual control of the camera, probably only just over 100 cameras are supported. This limitation is because many digital camera manufacturers refuse to share their camera communication specifications with their customers so the millions of users who run free operating systems have to rely on volunteers to reverse engineer things. Nikon and Canon cameras work well with gPhoto, so my Canon 50D seemed a natural candidate for experimentation with the command line interface.
To install it, enter
$ sudo apt-get install gphoto2
in a terminal or install it the slow, GUI way using Synaptic.
All the commands below are typed in a terminal. The dollar sign ($) represents the terminal, and should not be typed as part of the command!
Plug the camera into the USB port, and switch it on. If a popup appears, select DO NOTHING, and check ALWAYS PERFORM THIS ACTION. Otherwise, the camera will be locked and you will not have access to its functionality from gPhoto2. In the event that the camera does get mounted, you will see its icon on your desktop, and you can right-click it and unmount it before you go any further.
Get gPhoto to detect the camera, so enter
$ gphoto2 --auto-detect
This should produce the results below. If you see this, you know that gPhoto has detected your camera.
Model Port
-------------------------------------------------
Canon EOS 50D usb:
Canon EOS 50D usb:001,005
Next get a listing of the settings that are supported on your camera. Enter
$ gphoto2 --set-config capture=on --list-config
and you should see
/main/settings/eos-time
/main/settings/eos-synctime
/main/settings/capturetarget
/main/settings/capture
/main/imgsettings/eos-iso
/main/imgsettings/eos-whitebalance
/main/capturesettings/eos-exposurecompensation
/main/capturesettings/picturestyle
/main/capturesettings/eos-aperture
/main/capturesettings/eos-shutterspeed
/main/capturesettings/focuslock
This means you can control the features listed, notably eos-time, eos-synctime, capturetarget, capture, eos-iso, eos-whitebalance, eos-exposurecompensation, picturestyle, eos-aperture, eos-shutterspeed, focuslock.
You can retrieve the list of settings for each of those by using gphoto2 --set-config capture=on --get-config=/main/CATEGORY/SETTING, for example
$ gphoto2 --set-config capture=on --get-config=/main/capturesettings/focuslock
retrieves the photolock settings and outputs the results below:
Label: Focus Lock
Type: TOGGLE
Current: 2
The really cool thing that I wanted to try with gPhoto2 is tethered capture, a technique which is becoming popular among professional photographers. Nikon and Canon both sell applications for tethered capture, but they are proprietary and only work on Windows machines. I prefer to live free, so I decided to give gPhoto2 a run at tethered capture. I can think of lots of things that I can use tethered capture for, most notably, photographing hard to plan transient events, such as lightning, or the movement of insects under macro conditions.
I want to create a folder for the images to be stored in, so before I begin, I do:
$ mkdir tethered-photog
$ cd tethered-photog/
To get the camera to capture images, you can issue a command such as
$ gphoto2 --set-config capture=on --frames=3 --interval=15 --capture-image-and-download
which will capture three frames, 15 seconds appart, using whatever the current settings of the camera are.
You can also hook script to the command so that some processing is done once the photo is loaded to your hard disk. There is a sample script in /usr/share/doc/gphoto2/ called test-hook.sh. I will copy it in to ~/tethered-photog/ so that it is available in that folder when I run the capture.
$ cp /usr/share/doc/gphoto2/test-hook.sh ~/tethered-photog/
$ chmod 777 test-hook.sh
There is another application, Capture, that can be used for this purpose. The main advantage of Capture compared to gPhoto is that the consecutive shots are taken without the camera lenses being closed and opened again. When taking thousands images in a row, does not degrade the camera's life expectancy.
I am fortunate to live on a hill overlooking the city of Johannesburg, which in summer (this time of year) has a very dynamic sky as it is our rainy season. There is a lot of cloud formation and very heavy thunderstorms that build up from time to time. I love seeing time lapse of clouds, so I decided to experiment with a single cloud that I saw when I got home the second day after moving into the house. I plugged the camera into my Dell netbook running Ubuntu Karmic Koala. I set the camera not to shut off when on battery, mounted it on a tripod in the back yard. I set the camera to ISO 100, left the exposure on automatic, pointed the camera at the cloud, and executed the command below on the netbook.
$ gphoto2 --set-config capture=on --frames=200 --interval=100 --capture-image-and-download
When it was finished, I resized the images to 800X600 using the nautilus image plugin, and then executed the following commands to make the video:
$ ls -1t > files.txt
$ mencoder -nosound -ovc lavc -lavcopts vcodec=mpeg4 -o test.avi -mf type=jpeg:fps=8 mf://@files.txt
That's all it took. The resulting video is below. My next step will be to use an image library such as GD to automate the image resizing and then put the whole thing into a Bash script so it can be automated. Don't you just love Free Software?
linux photography timelapse
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