QSI 683csg Color 8.3mp CCD Camera, Mechanical Shutter, and Integrated Guider Port
The QSI 683csg color camera comes with an 8.3 megapixel Kodak Enhanced Response full-frame Color CCD image sensor with microlens technology. Integral Bayer RGB color filter array allows Single-Shot color imaging. The high quantum efficiency, wide dynamic range and low noise performance make the QSI 683 ideally suited to a broad range of demanding imaging applications.
The QSI 683csg includes the following:
- Single-shot color 8.3mp Kodak KAF-8300 sensor
- Integrated Guider Port
- USB 2.0 High-Speed, 16-bit output
- Dual read rates of 800kHz and 8MHz
- Air cooling to 45C below ambient
- Mechanical even-illumination shutter with shutter speeds down to 30ms
- Custom Foam Pelican Aluminum Case
600 Series cameras offer dual read rates optimized for a wide range of scientific and astronomical applications. The High Quality mode, which is about 50% faster than the 500 Series, is designed for applications where achieving the highest possible Signal to Noise Ratio is paramount. High Speed mode of approximately 8 million pixels per second supports applications requiring a higher frame rate. This allows the new 8.3mp 683 to download a full-frame bin 1x1 16-bit images in slightly more than one second.
The Model 683csg camera incorporates QSI's proprietary internal, even-illumination mechanical shutter in the 'mid-size' camera body configuration. The shutter is not only used for timing exposures, but can be left closed to produce 'dark frames' for subsequent image processing. Exposures can be as short as 0.03 seconds or as long as 240 minutes. The shutter is rated for more than 1 million cycles. Exposures can be fired under software control or with the use of the hardware input trigger.
Integrated Guider Port (IGP):
The available QSI Integrated Guider Port (IGP) solves many of the problems associated with existing guiding solutions. The QSI 600 Series WSG models solve the problems with other guiding systems by integrating a Precision Off-Axis Guider directly into the camera body with a pick-off prism (sensor) positioned in front of the integrated color filter wheel.
One of the main challenges when using a camera with an internal guide chip is to find a star bright enough to guide by within the limited field of view of the internal guide sensor. When shooting through red, green or blue filters, two-thirds (2/3) of the available light is blocked by the filter and not transmitted to the internal guider chip. This problem is compounded with narrowband filters where as little as 1% of the total light from a star reaches the guide chip. By positioning the pick-off prism in front of the filters, all of the guide star's light is available for guiding. By integrating the Guider Port into the camera, QSI was able to position the large ½" square pick-off prism very close to the Internal Filter Wheel while adding minimal backfocus and eliminating any possibility of flexure or rotation compared to a traditional off-axis guider system.
2-Stage TEC Standard:
QSI 600 Series cameras have a new cooling subsystem with a custom 2-stage TEC (thermoelectric cooler) that yields regulated cooling of greater than 45C below the ambient temperature. This allows 600 Series cameras to achieve a regulated temperature of -20C even in typical office/lab environments or in embedded systems. Astronomers also benefit, especially those in the hot southwest and humid southeast where night time temperatures may stay above 80F.
QSI cooled CCD cameras are designed to produce high quality images with extremely wide dynamic range, excellent linearity and exceptionally low noise:
The QSI 600 Series builds on the foundation of the popular QSI 500 Series. Dual read rates of up to 8 MHz with high-speed USB 2.0 and full 16-bit output allow 600 Series cameras to produce high quality images with high frame rates, extremely wide dynamic range, excellent linearity and exceptionally low noise. Cooling on the 600 Series is achieved with a 2-stage TEC supporting regulated cooling to greater than 45C below ambient, or greater than 50C below ambient temp with the optional Liquid Heat Exchanger.
The QSI 600 Series has seven different models employing a comprehensive range of monochrome and single-shot color scientific grade CCDs up to 8.3mp. A variety of options and accessories are available to meet your specific medical, astronomical or industrial imaging objectives.The superb imaging performance of 600 Series cameras is wrapped in an attractive, compact design with outstanding power efficiency and investment protecting upgradeability. The refined engineering, impressive fit and finish, and attention to detail will exceed your highest expectations.
The Benefits of Scientific Imaging Performance:
QSI's scientific-grade CCD cameras deliver image quality equal to or better than cameras costing thousands more. The lower noise and other benefits of a QSI camera allow you to capture better data in less time. What does scientific imaging performance really mean? There are four key traits that distinguish a scientific camera:
- High sensitivity
- Lower Noise
- Linear response to light
- Precisely regulated cooling
How sensitive a CCD it to light is expressed as its Quantum Efficiency (QE). Higher QE means you can collect more photons in any given amount of time giving you better looking images with a higher Signal to Noise Ratio (SNR). High sensitivity is almost purely a function of the CCD. Just about any camera using the same CCD will achieve a similar sensitivity to light. However, even with the same CCD, the Signal to Noise Ratio between two different cameras can be dramatically different especially in the fainter, lower signal areas of an image. These lower signal areas, such as the fringes of nebulae or dust lanes in a galaxy, often comprise some of the most interesting parts of astronomical images. Maximizing the SNR in these dim areas is the key to revealing those otherwise hidden details.
Lower Noise = Higher Dynamic Range:
Noise in a CCD camera is uncertainty in the signal you’re trying to measure. The lower the noise, the greater the dynamic range possible with any given CCD. There are several types of noise that contribute to the overall noise in a CCD image.
CCD images are super sensitive to any noise introduced by the camera’s electronics. Mitigating the electronic interference from the digital electronics and switching power supplies is one of the many challenges in designing and building a scientific grade CCD camera. Any noise introduced by the camera is relatively easy to see by analyzing bias frames. A Bias Frame is a zero-length (dark) exposure which captures the slightly varying “floor value” from pixel to pixel (the bias) plus any noise added during the process of reading the image from the CCD. By subtracting two bias frames, you can remove the underlying differences in the pixel bias leaving just the noise added to the image when it was read from the CCD. This subtraction of two bias frames is called a Read Noise Frame. Averaging together multiple bias frames (thus creating a histogram) can tell you more about the distribution of pixel values and make it easier to visually identify any non-Gaussian noise in the images. Bias frame histograms, however, don't tell the full story. The width and shape of the histogram shows the magnitude and overall distribution of the noise, but it tells you little about the structure of that noise. To do that requires another tool, the Fourier Transform.
A Fourier Transform is a mathematical function that converts a signal (any signal) into a collection of sine waves which together exactly represent the original signal. For images, the goal is 2-dimensional Fourier Transforms which convert an image from the Spatial Domain, rows and columns in a digital picture, into an equivalent Frequency Domain image. A Fast Fourier Transform (FFT) is a special algorithm that runs much faster on computers when starting with square images where each side has a length equal to a power of 2 (e.g 256, 512, 1024).
To analyze the noise from a CCD camera, you create a Read Noise Frame as described above. By subtracting two bias frames, you end up with just the noise introduced by reading the image from the CCD. An FFT of that Read Noise Frame will reveal any pattern noise introduced by the camera.
An FFT of random noise displaying a Gaussian distribution will have a smooth dark background with a single bright pixel in the center. To the left is an FFT of a Read Noise Frame from a QSI 600 Series camera. The FFT of the QSI Read noise frame reveals no pattern noise and is, in fact, virtually indistinguishable from an FFT of mathematically generated Gaussian noise.
Periodic noise will not be reduced when combining multiple images; instead it is reinforced, just like signal. The net effect of such noise is to raise the noise floor, reducing the signal to noise ratio and hiding the faint details in your images. When many such images are combined, periodic noise may show up as visible patterns, such as faint horizontal or vertical lines, running through your images.
- Lower noise displaying a Gaussian distribution will reveal subtle details in your targets that would otherwise be lost.
Accurately recording the relative amount of light between different objects requires a camera that delivers a linear response to varying levels of light. A CCD camera should record twice the photon flux from an object that is twice as bright. Cameras that use CCDs with anti-blooming protection will start to show a drop in linearity as the pixels begin to approach a high percentage of full well capacity, but should be nearly linear at lower signal levels.
The log scale graph below shows the response to light of a QSI 683cws-8 which uses an color full frame CCD with anti-blooming protection. the log scale of the graph amplifies any discrepencies from linear response especially at the lowest signal levels. The data points are linear to less then 1% all the way down to the lowest signal level, well within the specification of the CCD. Lower noise is especially critical in maintaining linearity at these lower signal levels.
High linearity is obviously critical for scientific applications such as accurate photometry, but it's just as important for producing beautiful pictures of deep sky objects. A linear response to light and lower noise allows you to accurately capture the subtle details of your targets in less time. To achieve the same signal to noise ratio in the faintest areas of your images with a higher noise camera can require hours more exposure time. Turning that around, a lower noise camera will yield great looking images with a higher signal to noise ratio in much less time.
Precisely Regulated Cooling:
Every image taken with a CCD camera has two distinct types of “signal”. A CCD records light striking it from the objects in your field of view, and it records heat from the sensor itself. Cooling the CCD reduces the contribution of this “thermal” current. With most Kodak CCDs, the amount of thermal current is cut in half for every roughly 6°C drop in the temperature of the CCD. So, dropping the temperature of the CCD by 36°C reduces the rate that thermal current builds by over 98%.
The rate that thermal current builds at any given temperature is very predictable and repeatable. That’s why dark frame subtraction is so effective. Subtracting an average or median combine of multiple dark frames taken at the same temperature as your light frames will remove the thermal current component (and bias) from your light frames. However, if the temperature varies either during the capturing of your light frames or dark frames by even a few tenths of a degree, dark frame subtraction becomes much less effective.
High sensitivity, low noise, a linear response to light and precisely regulated cooling are four key traits of a scientific camera. All are required in order to maximize the dynamic range of your images. Given a constant signal, lower noise increases the Signal to Noise Ratio and dynamic range, allowing you to produce better images in less time. Capturing good looking images of bright targets is relatively easy, but if you want great results in the dimmer areas of your targets, achieving the same signal to noise ratio with a higher noise camera can require hours of additional dark time.
All significant performance characteristics of QSI cameras, including Linearity, Read Noise, and Photon Transfer (Gain), are tested and documented as the final manufacturing step. Each camera's timing and voltages are carefully set to ensure maximum Charge Transfer Efficiency, and to minimize charge injection and other secondary noise sources.
QSI 683 CAMERA FEATURES:
|CCD Image Sensor||KAF-8300|
|Electronic Shutter||Mechanical, exposure range: 0.03 seconds to 240 minutes|
|Internal Color Filter Wheel||No||ws - 5-Position CFW
Holds 1.25" or opt. 31mm filters
|Camera Body Configuration||Medium
|Dimensions||W4.45” x H4.45” x D2.00”
(add 0.225" for T-Mount)
|5-pos, W4.45” x H4.45” x D2.50”
(add 0.225" for T-Mount)
|Weight, without Nosepiece||34 oz. / 950g||5-pos, 40 oz. / 1130g
|Optical Back Focus
(w/o Filters in path)
|0.90" w/ T-mount adapter
0.68" w/ C-mount adapter
0.68" w/ no adapter
|1.40" w/ T-mount adapter
1.18" w/ C-mount adapter
1.18" w/ no adapter
|Thermoelectric CCD Cooling||Temperature regulation +/- 0.1°C, @ 0°C to -40°C CCD temperature|
|In free air,
Fans @ Full Speed
|Typically 45°C below ambient air temperature with 85% cooling power|
|With Opt Liquid Cooling - Fans Off||Typically 52°C below circulating liquid with 85% cooling power
(adds 0.75" to camera depth)
|Cooling Fan Control||Intelligent, user configurable|
|Read Rate||User Selectable High Quality mode at 800KHz, High Speed mode at 8MHz|
|Camera Gain||User Selectable High Gain 0.5 e-/ADU (default), Low Gain 1.1 e-/ADU|
|Digital Resolution||16 bits (both High Quality and High Speed mode)|
|Total System Read Noise||Typically <8 electrons RMS (CCD specification limited) in High Quality mode
Typically <16 electrons RMS (CCD specification limited) in High Speed mode
|Pixel Dark Current||<0.1 electron per second at 0°C|
|Full Image Read and Download Time||Typically <12 second (host computer dependent) in High Quality Mode (800KHz)
Typically ~1 second (host computer dependent) in High Speed Mode (8MHz)
Image download times will be reduced with binning and/or subframe (ROI)
|Binning Modes||Symmetrical and Asymmetrical binning up to 9 pixels horizonally or vertically|
|Status and Notification||User configurable multi-color LED status indicator and multifunction
audible beeper. Over-temperature and high/low voltage alarms.
|Power Consumption||12v, 2A (24 watts) at max cooling, max fans and filter moving
(25 AC watts max with included 90-240V AC power supply)
|Operating Environment||Temperature: -20°C to 30°C, Humidity: 10% to 90% non-condensing|
|Computer Connectivity||USB 2.0 High Speed (USB 1.1 compatible)|
|Other Ports||Optically isolated 4 channel control port for telescope guiding
or input/output shutter trigger
The QSI 600 Series builds on the foundation of the popular QSI 500 Series. Dual read rates of up to 8 MHz with high-speed USB 2.0 and full 16-bit output allow 600 Series cameras to produce high quality images with high frame rates, extremely wide dynamic range, excellent linearity and exceptionally low noise. Cooling on the 600 Series is achieved with a custom 2-stage TEC supporting regulated cooling to greater than 45C, or greater than 50C with the option Liquid Heat Exchanger.
The QSI 600 Series has seven different models employing a comprehensive range of monochrome and single-shot color scientific grade CCDs up to 8.3mp. A variety of options and accessories are available to meet your specific medical, astronomical or industrial imaging objectives.
The superb imaging performance of 600 Series cameras is wrapped in an attractive, compact design with outstanding power efficiency and investment protecting upgradeability. The refined engineering and impressive fit, finish and attention to detail will surpass your highest expectations.
|Name||Quantum Scientific Imaging - QSI 683csg 8.3mp Cooled Color CCD Camera w/ Integrated Guider Port|