Point Grey Flea3 monochrome CCD camera
The Sun, Moon and brighter planets rank among the most alluring astrophotography targets due to the intricate detail they present. We’ve been imaging them for centuries – the first photograph of the Moon was taken in 1840. Our tools and techniques have come
a long way since then, but like the early pioneers we still have to deal with the distortions introduced by Earth’s turbulent atmosphere. Astronomers describe the stillness of the atmosphere as ‘seeing’.
The Moon appears to shimmer and wobble when seen through a telescope. However, there are brief periods of good seeing, where everything looks steady. This is almost impossible to capture reliably with a stills camera, but the Point Grey Flea3 CCD camera tackles the task head-on. In this review, we’ve tested the FL3-FW-03S1M-C, a high-speed monochrome version of the camera; a one-shot colour model is available too.
Like other planetary cameras, the Flea3 takes lots of still images in rapid succession. Among the captured frames will be a few good, steady images. You can use computer software such as RegiStax or AviStack to extract and average the
good frames to produce a clean and smooth end result.
The camera model we tested is able to record images at up to 120 uncompressed frames per second (fps). In order to cope with the large amount of data produced, the camera needs to be connected to a computer using a high-speed FireWire 800 (IEEE 1394b) link. Not all computers have FireWire, so you’ll need to check that yours does or at least that it can be added by a plug-in card before buying the camera. These items, as well as any extra cables, are also sold by Point Grey. We used a FireWire 800 ExpressCard adaptor in our laptop, as well as an external power supply for the camera, which were supplied to us for the purpose of this review.
The camera is controlled by Point Grey’s FlyCapture 2 software, which can be downloaded along with the necessary drivers from the company’s website. You can also use a freeware third-party program called FireCapture, which has been written by planetary imagers and offers useful enhancements over FlyCapture 2. We successfully operated the Flea3 using both programs.
At 120fps, each exposure is short, so the camera’s sensor needs to be very sensitive. The Flea3 uses the Sony ICX618, which has low noise and is most sensitive in the orange-red part of the spectrum. This is excellent news for planetary imagers as good detail can often be seen through a red filter.
The camera also works well in the infrared part of the spectrum – you may want to use an infrared-pass filter because they produce high-contrast detail. They also help to steady the view, as longer wavelengths of light are less affected by seeing.
Using an infrared-pass filter dims the image considerably, but we were impressed with the brightness the Flea3 returned when we used one. Imaging the Moon and Jupiter with a 742nm infrared-pass filter gave us a good bright signal while maintaining a very respectable frame rate.
The capture speed is extremely impressive. In one session we imaged a last quarter Moon in several parts, assembling each piece into what’s known as a lunar mosaic: essentially a giant lunar jigsaw puzzle. We used a Celestron C14, which has
a focal length of 3.85m, at prime focus (f/11). The scope size combined with the Flea3’s relatively small 0.25-inch chip, meant the whole mosaic required a staggering 166 panes to complete. Each pane was distilled out of a 1,000-frame capture, so that means in total we recorded 166,000 frames.
Once we’d started the task and had got into our rhythm, the superb efficiency of the Flea3 meant that it took us just 45 minutes to complete the mosaic. You can see a fully zoomable version of the end result online at www.zoom.it/ephS#full.
It is a definite thumbs up for this diminutive camera. They say that speed can be addictive and this is a prime example: switching back to an older 60fps camera for some follow-on work revealed just how much the Flea3 had spoilt us.
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