||Home > 500 Series > QSI
4.2mp 540wsi allows LRGB imaging through standard 1¼" filters
resulting in a breakthrough in
size, weight and cost.
- 4.2mp 2048x2048 KAI-04022 sensor
- Low noise, wide dynamic range
- Very fast electronic shutter
- Up to 45°C CCD cooling
- Available mechanical shutter
- Available internal 5-position color filter wheel
- Available integral Off-Axis Guider (OAG)>>
- MaxIm DL and CCDSoft Drivers
- Available MaxIm DL or LE camera control and
image processing software
- ASCOM-compatible Windows COM API
- Linux drivers and API
QSI 540 4.2mp Scientific
Cooled CCD Camera
Breakthrough QSI image quality
now with a larger sensor
at a breakthrough price!
The QSI 540 model camera employs a 4.2mp Kodak interline transfer CCD image sensor with microlens technology. The increased Field of View, high quantum
efficiency, wide dynamic range and low noise performance make the 540i ideally
suited to a broad range of demanding astronomical, scientific, medical and industrial
Because the internal color filter wheel is positioned very close to the focal plane in QSI 500 Series cameras, the 21.4mm diagonal Kodak KAI-04022 sensor experiences no optical vignetting through standard 1¼" filters, even with fast optical systems.
The compact design of the QSI 500 Series allows the 540 to set a new benchmark for cost and size in a
high performance, full-featured scientific CCD camera. With optional features
and upgradeability, the QSI 540 can be tailored to fit your needs today and in the future.
The 540 camera system is supported by industry leading image
acquisition software and development tools are available for creating custom Windows or Linux imaging applications.
The QSI 540wsg is now available with an integral Off-Axis Guider allowing you to guide using the light from your main telescope while picking off the light from the guide star in front of the filters.
Learn more about the available built-in OAG>>
Starting at $3,695
Single Shot Color 540c also available
Click here for details>>
|Large 4.2mp Sensor
The large 2048x2048 sensor in the QSI 540, shown to the left approximately life size, provides unprecedented field of view in a camera using standard 1¼" filters.
The compact design and internal color filter wheel of the QSI 540wsi allows unvignetted, filtered images even with very fast optical systems.
Innovative, Aesthetic Body Design
Small enough to practically hide behind a CD-ROM, the medium format QSI 500 Series family
sets new standards for full-featured, high performance scientific CCD cameras. The
striking appearance, refined design and superior fit and finish only hint at the advanced
technical performance lurking inside. Some have described it as a work of art.
A defining feature of the 500 Series is the flexible design that permits three progressively
configured body styles with a minimal impact on overall size. The relative sizes of the three body configurations,
Slim, Medium, and Full, can be seen in the image to the right. A camera's body size depends
on the internal features installed.
The Slim body is the thinnest version
and can be used with CCDs incorporating an electronic shutter. The
Medium body provides addition space for an internal mechanical shutter. The Full body
allows the installation of both the shutter and a five position filter wheel with
Engineered with extensive use of sophisticated CAD-CAM design tools, the 500 Series is CNC
machined from aircraft grade aluminum alloy. The finely finished anodized body
components are assembled with corrosion resistant stainless steel hardware throughout.
Small, Light-Weight and Thin
The 500 Series is designed to support image sensors with a maximum diagonal measurement of 22mm,
characterizing the family as Medium Format cameras. For this class of camera they are surprisingly
compact. At just 4.45" square, the Slim body camera is just 1.68" deep, occupying less than 30
cubic inches and weighing in at under 26 ounces. Even a Full body camera with shutter and color
filter wheel is only 2.5" deep and a mere 40 ounces. In fact, the small footprint is the practical
limit for a camera with a 5 position filter wheel using standard 1.25" interchangeable filters.
Keeping the depth of the camera to a minimum was an early design goal. Not only
is backfocus minimized, but the camera moment-arm is reduced resulting in greater stability.
spaces, like through the forks of an SCT telescope, are no longer a problem. The shutter and
filter wheel were placed inside the body, very close to the image sensor reducing backfocus and
overall depth. The motion control electronics are actually buried in the 0.12" thick shutter/filter
mounting plate to reduce depth further. Pulling the cooling fans and heatsinks into the body
resulted in another significant reduction in depth. Finally, having all electrical cables and the
optional liquid heat exchanger recirculation hoses exit the body in
the same direction and perpendicular to the optical
axis insured an interference-free fit in tight spaces.
More Camera and Application Photos >>
4.2 Megapixel CCD Image Sensor
The QSI 540 camera employs a Kodak KAI-04022 4.2 megapixel interline
transfer CCD image sensor
with microlens technology. The KAI-04022M sensor has a photoactive array of 2048W x
It has excellent quantum efficiency between 350nm and 1000nm with significant
enhancement at the blue
end of the spectrum. Low dark current and high pixel charge capacity result in a dynamic range
exceeding 74db. The sensor employs a vertical overflow drain that provides both
antiblooming protection and a fast electronic shutter. Micro lenses cover the
surface of the CCD to focus the light
into each pixel to increase optical response.
See the Specifications tab for more detail.
High Performance Design
"The QSI 500 Series scientific camera family was designed from the ground up to attain the
highest possible imaging performance from Kodak's KAF and KAI CCD image sensors."
- Sophisticated mixed-signal design practices are utilized throughout the camera. This permits
a very compact design while eliminating interference from conducted and radiated noise. All
of the many internal clock and bias voltages are set via high precision Digital to Analog
Converters (DACs) under computer control, allowing automated optimization during manufacture.
ROHS compliant multi-layer circuit boards and surface-mount components are used exclusively.
A unique circuit board stacking methodology eliminates interconnecting wires that could
- Arguably, the most important aspect of a CCD camera design is the video processing subsystem.
This is where almost all of the camera's performance characteristics are established. The
500 Series video processing begins with a very low noise, precision preamp to accurately
amplify the microvolt level pixel signal from the CCD image sensor. This signal is then
processed through a Correlated Double Sampler (CDS) to reduce temporal read noise in
the pixel signal. Subsequent signal conditioning then feeds the pixel level to a high-speed,
precision 16 bit Analog to Digital Converter (ADC) where it is converted to a digital value
between 0 and 65535.
The Read Noise contributed by this entire subsystem is exceedingly small. So small in fact,
that it is virtually undetectable, contributing less than 1/30 of the combined read noise
of a typical KAF image sensor. The low read noise and carefully chosen camera gain yield
excellent Dynamic Range. Linearity is also outstanding, limited only by the CCD image
- An internal pipelined data architecture with a large FIFO memory buffer is employed to
achieve a constant 500,000 pixel/second read rate from the CCD. The multi-controller
design effectively decouples the camera pixel read operation from the USB
transfer process while
ensuring maximum throughput.
- A carefully designed and isolated switching power supply generates all of the voltages
needed to operate the camera from a single 12VDC power source. Low noise design practices
and advanced filtering techniques completely eliminate any measurable impact on camera
- All significant performance characteristics, including Linearity,
Read Noise, and Photon
Transfer (Gain), are tested and confirmed during manufacture. Each camera's timing and
voltages are carefully set during manufacture to ensure maximum Charge Transfer Efficiency,
and to minimize charge injection and other secondary noise sources. QSI's exclusive
ResearchSpec® profiling ensures optimal performance in every camera.
CCD Cooler Subsystem
Key in the compact design of the 500 Series cameras is a very efficient 12 watt
thermoelectric CCD cooler subsystem. Intelligent, programmable cooling fans are integrated
into the rear of the camera body to remove the heat generated by the cooler.
Typically, forced air cooling lowers the regulated CCD temperature by 38°C below ambient
utilizing 85% power. Tight +/- 0.1°C temperature regulation is maintained at temperature
of 10°C below ambient and lower. A slim liquid heat exchanger
(shown at right) can be attached to
the rear of the camera body to increase the cooling further, up to 45°C below the
temperature of the circulating fluid.
The cooled CCD image sensor is positioned in a hermetically sealed environmental chamber
covered with an
anti-reflection coated precision optical window. The chamber is purged with an ultra dry noble
gas to minimize the frost point and heat conduction. To extend the useful period
before re-purging is required, a user-rechargeable microsieve desiccant is employed to scavenge water molecules
that enter the chamber. It is located behind a sub-micron, permeable membrane to prevent
particulate contamination of the CCD chamber.
Cooling and Dark Current
Effective cooling of the CCD image sensor is essential for long exposure imaging, especially
in astronomy. Thermally generated electrons accumulate in the pixels over time
and compete with the electrons that make up the image. This accumulation of thermal
electrons is known as 'dark current'. It lowers the dynamic range of the sensor and reduces
the signal to noise ratio. Eventually the thermally generated electrons will swamp the image.
Fortunately, dark current can be reduced dramatically by cooling the CCD. Kodak KAF CCD
sensors accumulate thermal electrons at a rate of roughly 4 electrons per second
per pixel at 25°C.
With every 6.3°C decrease in temperature the dark current is reduced by half. Where a 10
minute exposure might generate 2400 thermal electrons at 25°C, it will produce only about
10 at -25°C. This is a very small number when compared to the CCD read noise of
15 electrons and the pixel capacity of 100,000 electrons. At -35°C, a 1 hour
exposure will generate less than 20 thermal electrons per pixel!
The 540i utilizes the electronic shutter built into the KAI-04022 CCD image sensor to
control exposures. Shutter timing is very precise and can range from as short as 100
microseconds up to 240 minutes. The very fast acting shutter is possible due to two key
features of the interline transfer architecture.
- Any existing electrons can be removed from the pixels instantly with
a single electronic pulse, beginning the exposure.
- After the specified exposure duration, the entire image field can be
instantaneously moved into a light-shielded holding area on the CCD. The image
is then read out at the normal rate without being contaminated by any light
still illuminating the CCD surface.
The Model 540si camera incorporates the optional internal mechanical shutter in
the 'mid-size' camera body configuration. When operating with an interline
transfer CCD, a mechanical shutter is not used to actually make the exposure.
This is still the responsibility of the electronic shutter. The mechanical
shutter is employed to cover the CCD and simplify the creation of Dark and Bias frames for
subsequent image processing.
The Model 540wsi adds an internal five position filter wheel to the camera in a 'full-size' camera
body. Even with the large 4mp sensor, the short backfocus and close spacing provided by the internal color filter wheel allows the 540wsi to work even with optics faster than f/4.5 with no significant vignetting. The filter wheel accepts any standard 1.25" filters and is available with LRGB color filters.
Various filter configurations are available. Optionally,
the camera can be supplied without filters allowing you to use any filters you choose.
The filter wheel can be easily removed and replaced to change or clean the glass filters. Additional
filter wheels can be purchased allowing quick interchange of different filter set configurations.
(Note how the RGB filters reflect the complimentary color in the picture at the
LRGB Filter Set
Astronomik Type IIc LRGB filters are the standard filters available with the 540wsi camera (filters from other
manufacturers are available by request.) The Astronomik filters are optimized for astronomical
color imaging and the bandpass is designed to accurately match the color sensitivity of the human eye.
Infrared cutoff down to 1150nm is integrated into each filter eliminating the need for an extra IR
filter. These thickness-matched filters are par-focal with excellent transmission to nearly 100%.
The chart below illustrates the bandpass characteristics of each filter.
Integral Off-Axis Guider
Selecting the best guiding solution has always required a compromise. The available, integral off-axis guider (OAG) solves many of the problems associated with existing guiding solutions.
The Right Guiding Solution
Guiding with a separate guide scope provides the most flexibility, but differential flexure can be an issue, especially with long focal length scopes. With an internal guide chip, you're forced to guide with light through your filters and you can't guide at all while the shutter is closed or an image is being downloaded. This is especially problematic for narrowband imagers. To get around those issues, you could add an external off-axis guider, but a traditional OAG can add an inch or more of back focus plus more weight and two new mounting surfaces that need to be held rigidly.
Guide with Light From
in Front of the Filter Wheel
The QSI 500 Series "wsg" models solves the problems with other guiding solutions by integrating a Precision Off-Axis Guider directly into the camera body with the pick-off prism positioned in front of the integrated color filter wheel – right where it belongs.
Never Struggle With Finding a Guide Star
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 intenal guide sensor. When shooting through red, green or blue filters, ⅔ of the available light is blocked by the filter and not transmitted to the internal guider chip, guaranteeing lower signal-to-noise stars for guiding. 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, you always have all the star's light available for guiding.
Integrated OAG Supports Fast Optical Systems
By integrating the Off-Axis Guider into the camera, we're able to position the pick-off prism very close to the internal filter wheel adding minimal backfocus and eliminating any possibility of flexure or rotation compared to a traditional OAG. The large ½" square pick-off prism is optimally positioned close to the internal filter wheel, supporting the use of guide cameras with large sensors, while preventing any vignetting of the main sensor even with very fast optical systems.
Flexible Guide Camera Options
The Off-Axis Guider (OAG) built into 500 Series "wsg" models is designed to support any camera with 12.5mm of back focus or less that can be attached using C-mount or T-mount threads. Many cameras are designed with 12.5mm of back focus to be compatible with CS-mount lenses. CS-mount lenses use the same thread as C-mount (1" x 32tpi) but with 12.5mm of back focus as opposed to 17.5mm for C-mount.
Click here for a list of guide cameras known to be compatible >>
Easy, Rigid Guide Camera Focusing
The guide camera attaches to the "wsg" using a C-mount or T-mount threaded adapter (specified at time of order). The threaded adapter sits on top of the focus ring and allows the guide camera to be rotated to any position. The focus ring threads onto the focus base to allow 3mm of travel when focusing the guide camera. Once focus is achieved, the focus ring is locked with a set screw. The guide camera can still be rotated manually if desired without changing the focus. The end result is a rigid, easily focused guide camera that will not move or flex while your mount tracks the apparent motion of the night sky.
The connector panel, shown above, is thoughtfully recessed into the body of the camera for
protection and provides access for all external connections. The two threaded holes on the
back of the body are used to attach an optional cable restraint system to support the
electrical connections as well as the recirculation hoses if the liquid heat exchanger
All 500 Series cameras utilize a standard USB 2.0 (USB 1.1 compatible) port for connection to the
host computer and imaging application software. Read and transfer time for an entire
2048x2048 image frame is typically less than eleven seconds.
A four channel optically isolated control port is accessible through a standard 6 pin modular
connector. The signal pin-out is compatible with most modern telescope mount drive correctors
and is intended to be used for telescope guiding under MaxIm/DL and CCDSoft. The outputs can
also be used for other control purposes when developing your own applications with the 500
Series ActiveX software development toolkit. The outputs are common emitter, open-collector and
can sink up to 50ma. The maximum voltage should not exceed 50v.
One of the defining features of the 500 Series cameras is power efficiency. A
fully configured 540wsi camera operates from a single 12v DC supply and only consumes 18 watts at full cooling, with both
fans at maximum and the filter wheel moving. Other camera model configurations have power consumption
as low as 3.5 watts. Included with each camera is an approved 12 volt DC power supply with an input
voltage range of 90-240V, 50-60HZ.
Both visual and audible notification is built into all 500 Series cameras. A multi-color LED status display
provides visual indication of the various states of camera operation. The
behavior of the
indicator is configurable and can be disabled by user command. A unique internal beeper provides
audible feedback of camera operation and status. Like the visual display, the beeper can be
configured and disabled by the user.
Comprehensive Software Support
Every 500 Series camera is accompanied by a collection of software applications
and tools that allow you to begin imaging immediately or develop custom camera control applications
to precisely match your requirements.
View complete 500 Series Software details >>
MaxIm LE and MaxIm DL
MaxIm LE is based on the award winning MaxIm DL version 4.5 from Diffraction Limited
providing the fastest and easiest way to image the night sky. All QSI Series 500
cameras are supported for imaging and auto-guiding, plus most popular guider cameras
are supported as well. MaxIm LE is available with any 500 Series camera. You can upgrade to MaxIm DL/CCD for an attractive price
at the time of purchase. Details >>
Drivers for Software Bisque's CCDSoft
Realizing that one shoe doesn't fit all, QSI also supplies the necessary drivers
for CCDSoft, the popular Image Processing and Camera Control Software from Software Bisque.
Windows Custom Application Development
QSI provides an ASCOM-compatible API (Application Programming Interface) enabling users to write their own custom camera control
applications. The camera control API is an automation component
that communicates with the camera device driver and exports a COM automation
interface. COM automation provides an interface which Microsoft Office, VB, VBA,
C++, and other Windows applications can use to control the camera.
The API is available as part of the QSI Software Development Kit (SDK), available for download
from the QSI website.
Learn more about the ASCOM Initiative.
Linux Custom Application Development
QSI provides a camera control C++ API for Linux users on Intel x86-compatible platforms. The API provides full camera control and image capture capabilities via the USB interface. The API is implemented as a shared library providing an easy to use camera object that exposes all of the features and capabilities of the camera. It is well suited for both simple scripting, and more sophisticated imaging application development.
Field Upgradeable Firmware
All 500 Series cameras can be upgraded to the latest firmware in the field. The latest
firmware is always available for download from the QSI Software page. QSI supplies a simple
fail-safe Updater application that handles all the details.
|Model 540 CCD Image Sensor
|CCD Manufacturer & Model
||Yes - 300x suppression
|Imager Size: (WxH)
||15.15mm x 15.15mm
|Pixel Array (WxH):
||2112x2072 total pixels, 2048x2048 active (visible)
||7.4µm x 7.4µm
|Pixel Full Well Depth
|Absolute Quantum Efficiency
||Peak: 55% at 500nm
|Pixel Dark Current
||<0.1 electron per second at 0°C
|Intrinsic Read Noise
||<8 electrons RMS
|Charge Transfer Efficiency
||Manufacturer's CCD Imager
Model 540 Camera Specifications
(See additional 540wsg specifications>>)
|CCD Image Sensor
||100µsec to 240 minutes
||100µsec to 240 minutes
||100µsec to 240 minutes
|Internal Color Filter Wheel
||Yes - 5 Position, 1.25" std filters
|Camera Body Configuration
||W4.45” x H4.45” x D1.68”
(add 0.225" for T-Mount)
|W4.45” x H4.45” x D2.00”
(add 0.225" for T-Mount)
|W4.45” x H4.45” x D2.50”
(add 0.225" for T-Mount)
|Weight, without Nosepiece
||26 oz. / 740g
||34 oz. / 950g
||40 oz. / 1120g
|Optical Back Focus
(without Filters in path)
|0.58" w/ T-mount adapter
0.68" w/ C-mount adapter
0.35" w/o mounting adapter
|0.90" w/ T-mount adapter
0.68" w/ C-mount adapter
0.68" w/o mounting adapter
|1.40" w/ T-mount adapter
1.18" w/ C-mount adapter
1.18" w/o mounting adapter
|Thermoelectric CCD Cooling
||Temperature regulation +/- 0.1°C, @ 0°C to -40°C CCD
|In free air,
Fans @ Full Speed
|Typically 38°C below ambient air with 85% cooling power
|With Opt Liquid Cooling - Fans Off
||Typically 45°C below circulating liquid with 85% cooling power
(adds 0.75" to camera depth)
|Cooling Fan Control
||Intelligent, user configurable
||User Selectable 0.8 e-/ADU, 1.9 e-/ADU
|Total System Read Noise
||Typically <8 electrons RMS (CCD specification limited)
|Pixel Dark Current
||<0.1 electron per second at 0°C
|Full Image Read and Download Time
||Typically <11 second (host computer dependent)
||Symmetrical on-chip 2x2 and 3x3, user selectable
Asymmetrical binning up to 3 pixels in either dimension
|Status and Notification
||User configurable multi-color LED status indicator and
audible beeper. Over-temperature and high/low voltage alarms.
||12v, 1.5A (18 watts) at max cooling, max fans and filter moving
(25 AC watts max with included 90-240V AC power supply)
||Temperature: -20°C to 30°C, Humidity: 10% to 90% non-condensing
||USB 2.0 (USB 1.1 compatible)
||Optically isolated 4 channel control port for telescope guiding
or other application specific control
|T Mounting Adapter
||Standard adapter - T-Thread, 42mm x .75mm
C Mounting Adapter
(1" x 32TPI)
(Not recommeded for 540i)
|Optional, C-Mount lens focus compatible
|Optional, C-Mount lens focus compatible
|Optional, for non-lens adapters
and accessories (standard
C-Mount lens does not reach
||Standard, T-Adapter to 2" nosepiece
Optional, T-Adapter to 1.25" nosepiece
The following standard items are included
with every QSI 540i, s, and ws camera:
(See 540wsg standard items>>)
- T-Mount Camera Adapter*
- T-Mount Adapter Cover*
- T-Mount to 2" Nosepiece*
- 12VDC / 90-240VAC power supply
- 10' USB 2.0 Interface Cable
- 10' Standard Guider Cable
- QSI Software Installation CDROM
- Drivers for MaxIm DL/CCD and CCDSoft
- ActiveX Developer's Toolkit
- Custom Fit Pelican Storage Case
View all Accessories >>
* Other options are available at
of purchase. See Configure Camera page...