SBIG AllSky 340 Monochrome Camera
This SBIG AllSky 340 is a monochrome All Sky Camera that uses a Kodak KAI-340 CCD sensor, with 640x480 pixels, 7.4 microns square, and a high gain output stage for excellent sensitivity. The All Sky camera incorporates the SBIG Smart Guider Camera inside an aluminum enclosure with an acrylic dome to protect the included Fujinon 1.4mm f/1.4 fisheye lens. The image shown above was a 60-second exposure, taken from a light polluted backyard - the first quarter moon had just set behind the roof.
The new SBIG AllSky-340 All Sky Camera has some very interesting features that make it much more versatile than other All-Sky cameras that SBIG manufactured in the past. First of all, it has an RS-232 link to the PC for control and image download. While this interface is very slow in comparison to USB, it will tolerate 100 foot (30 meter) cable runs. Or, you can throw away the cable and use a Bluetooth wireless link with an optional inexpensive adapter. And, the unit is low power and can be powered by a solar array (also optional) so you don't need any wires AT ALL running from your PC to the camera! The beauty of this set-up is the fact that the unit can be located where it has a good view of the sky, instead of good access to a power plug or PC. Your roof is now the preferred location, above the trees and neighbor's houses!
By actual test, an RS-232 link, using a USB to RS-232 adapter running at 460.8 Kbaud, with a 100-foot cable, downloads a full image reliably in 15 seconds. At 115.2 Kbaud a full image takes 60 seconds. Bluetooth wireless adapters will typically run at 115 K-baud, and the one SBIG tested worked reliably at a distance of 75 feet. With wireless links, one must minimize the number of walls you have to pass through. Each wall (2 layers of drywall or wood) costs about a factor of two signal and range.
These may seem like rather long download times compared to the USB 2.0 interface of SBIG's last AllSky camera, but the SBIG AllSky-340 can take an image while transmitting, so with exposures longer than the download time the camera is only insensitive for the length of the readout of the CCD, which takes place in less than 1 second to an internal memory buffer in the camera. As a result, the camera is excellent for meteor detection. Its field of view is wider than previous meteor cameras, so it should see much more meteors near the horizon. One other plus to be considered is the software can run continuously in the background while you use your computer for other tasks. At these slow download rates, the computational workload is so slight your applications won't even notice. It will not interfere with regular imaging using the same PC. The All-Sky image is there when you want to view it.
The included fisheye lens is Fujinon's new FE185C046HA-1, with a 1.4 mm focal length, F/1.4. SBIG has tested this lens and the image quality is excellent wide open, all the way to the horizon. The fisheye lens is mounted to a plate which can be translated, tipped, and focused relative to the CCD, so the full resolution of the lens can be achieved. This plate is also heated to keep the lens free of condensation. The heat rises into the acrylic dome, warming it to keep the dew off and dry raindrops. The inexpensive acrylic dome is easily replaced by removing a few screws, allowing for routine replacement in the field as the dome suffers the inevitable scratches and damage due to sunlight, windblown dust, and disrespectful birds. SBIG will maintain a supply of replacement domes. The prototype shown here is black ƒthe production version will have a white body so it doesn't get too hot in the sun. The enclosure is 5.5 x 5.5 x 11 inches in size (14x14x28 cm).
The SBIG AllSky-340 camera can also take exposures as short as 50 microseconds, so daylight operation is possible, allowing recording of cloud conditions 24 hours a day. A blooming streak will be noted vertically through the sun, but otherwise, the image is excellent.
SBIG also intends to modify the existing meteor camera software to support this new camera and enable bright meteor detection and recording while you sleep. Iridium flares, space station overflights, and brighter satellites will also be captured, along with the occasional What is that we think the new All Sky camera will provide a very useful tool for the amateur with an automated setup trying to avoid clouds, those users interested in watching for fireballs, and those who simply wish to capture movies showing the beauty of the sky rotating endlessly over their heads. The software has the ability to capture AVI files and display them afterward. The file storage requirements are around 72 megabytes a day for 24 hours coverage, one frame a minute.
|Dynamic Range||11.5 Stops|
|Mega Pixels||0.3 mp|
|Pixel Array||648 x 486|
|Pixel Size||7.4 microns|
|Power Consumption||12V 0.6A|