QSI  Home Page

QSI 540c
Home > 500 Series > QSI 540c

  • 4.2mp 2048x2048 KAI-04022 sensor
  • Single-Shot color imaging
  • Low noise, wide dynamic range
  • Very fast electronic shutter
  • Up to 45C CCD cooling
  • Available mechanical shutter
  • Available internal 5-position color filter wheel
  • MaxIm DL and CCDSoft Drivers
  • Available MaxIm DL and LE camera control and image processing software
  • ASCOM-compatible Windows COM API
  • Linux drivers and API 520i

Why QSI?
Why QSI?

QSI 540c 4.2mp Scientific
Cooled CCD Camera

Breakthrough QSI image quality
now with a larger sensor
at a breakthrough price!

The QSI 540c model camera employs a 4.2mp Kodak interline transfer CCD image sensor with microlens technology. Integral Bayer RGB color filter mask allows Single-Shot color imaging. The increased Field of View, high quantum efficiency, wide dynamic range and low noise performance make the 540c ideally suited to a broad range of demanding astronomical, scientific, medical and industrial imaging applications.

With the built-in mechanical shutter, the 540csi supports unvignetted imaging with extremely fast optics down below f/2.3, and the electronic shuttered 540ci will work with optical systems faster than f/1.
The 500 series sets a new benchmark for compact design and power efficiency in a high performance, full-featured scientific CCD camera. With optional features and upgradeability, the 540c can be tailored to fit your needs today and in the future.

The 540c camera system is supported by industry leading image acquisition software and development tools are available for creating custom Windows or Linux imaging applications.

Starting at $3,995  
Configure Camera

Monochrome 540 also available
Click here for details>>

Innovative Design
High Performance CCD Image Sensor
Leading Edge Technical Performance
Efficient, Low Power CCD Sensor Cooling
Two Shutters and
Color Imaging
Connectivity and Notification
Extensive Software Support
Large 4.2mp Sensor

The large 2048x2048 sensor with integral Bayer filter array, shown to the left approximately life size, provides the QSI 540c with a wide Field of View.

The compact design of the QSI 500 Series allows the QSI 540csi to support fast optical systems down to f/2.3 with the mechanical shutter and below f/1 using just the electronic shutter in the 540ci.

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 interchangeable filters.

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. Tight 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 540c model camera employs a Kodak KAI-04022 4.2 megapixel interline transfer CCD image sensor with microlens technology. The integral RGB Bayer color filter mask allows Single-Shot color imaging. The KAI-04022M sensor has a photoactive array of 2048W x 2048H pixels. 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. The diagram below shows the image sensor response for the three built-in color filters.


  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 reduce reliability.
  • 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 sensor itself.
  • 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 noise performance.
  • 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 38C below ambient utilizing 85% power. Tight +/- 0.1C temperature regulation is maintained at temperature settings of 10C 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 45C 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 25C. With every 6.3C decrease in temperature the dark current is reduced by half. Where a 10 minute exposure might generate 2400 thermal electrons at 25C, it will produce only about 10 at -25C. 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 -35C, a 1 hour exposure will generate less than 20 thermal electrons per pixel!

Electronic Shutter
The 540ci 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.

Mechanical Shutter

The Model 540csi 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.

Single-Shot Color Imaging

Single-Shot color imaging is made possible by overlaying the pixels on the CCD with an alternating red, green and blue color filter matrix at the time of manufacture. This is also how the vast majority of color video and still cameras create color images. The raw image from the camera requires further processing to extract the color and luminance information and create a final image. Most CCD image acquisition software, inlcuding MaxIm LE and MaxIm DL, has special processing for just this purpose.

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 is employed.

USB Interface

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.

Guider/Control Port

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.

Power Requirements

One of the defining features of the 500 Series cameras is power efficiency. A fully configured 540csi camera operates from a single 12v DC supply and only consumes 18 watts at full cooling, with both fans at maximum. 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.

ASCOM 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 540i CCD Image Sensor Specifications 
Feature Standard
CCD Manufacturer & Model     Kodak KAI-04022C       
CCD Architecture Interline Transfer
     Microlens Yes
     Anti-blooming Yes - 300x suppression
     Color Filters Yes - Internal RGB, on CCD Bayer color filter mask
Imager Size: (WxH) 15.15mm x 15.15mm
Pixel Array (WxH): 2112x2072 total pixels, 2048x2048 active (visible)
Pixel Size: 7.4µm x 7.4µm
  Typical Values
Pixel Full Well Depth 40,000 electrons
Absolute Quantum Efficiency Peak: 55% at 500nm
Pixel Dark Current <0.1 electron per second at 0C
Intrinsic Read Noise <8 electrons RMS
Dynamic Range 74db
Charge Transfer Efficiency >0.99999
Manufacturer's CCD Imager Specifications
KAI-04022M (PDF)

Model 540i Camera Specifications  (Preliminary - May 2008)

Feature Model 540ci Model 540csi
CCD Image Sensor


Electronic Shutter 100sec to 240 minutes 100sec to 240 minutes
Mechanical Shutter No Yes
Internal Color Filter Wheel No No
    Filters None None
Camera Body Configuration Slim
Dimensions 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)
Weight, without Nosepiece 26 oz. /  740g 34 oz.  /  950g
Optical Back Focus
(without Filters in path)
0.61" w/ T-mount adapter
0.68" w/ C-mount adapter
0.39" w/o mounting adapter
0.90" w/ T-mount adapter
0.68" w/ C-mount adapter
0.68" w/o mounting adapter
Thermoelectric CCD Cooling Temperature regulation +/- 0.1C, @ 0C  to -40C CCD temperature
In free air,
Fans @ Full Speed
Typically 38C below ambient air with 85% cooling power
With Opt Liquid Cooling - Fans Off Typically 45C below circulating liquid with 85% cooling power
(adds 0.75" to camera depth)
Cooling Fan Control Intelligent, user configurable
Camera Gain User Selectable 0.8 e-/ADU, 1.9 e-/ADU
Digital Resolution 16 bits
Total System Read Noise Typically <8 electrons RMS (CCD specification limited)
Pixel Dark Current <0.1 electron per second at 0C
Full Image Read and Download Time Typically <11 second (host computer dependent)
Binning Modes 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 multifunction
audible beeper. Over-temperature and high/low voltage alarms.
Power Consumption 12v, 1.5A (18 watts) at max cooling, max fans and filter moving
(25 AC watts max with included 90-240V AC power supply)
Operating Environment Temperature: -20C to 30C, Humidity: 10% to 90% non-condensing
Computer Connectivity USB 2.0 (USB 1.1 compatible)
Other Ports 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
(17.5mm backfocus)
Optional, C-Mount lens focus compatible
(17.5mm backfocus)
Nosepiece Standard, T-Adapter to 2" nosepiece
Optional, T-Adapter  to 1.25" nosepiece
The following standard items are included
with every QSI 540i camera:

  • 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
the time of purchase. See Configure Camera page...

Options and Accessories
Power Supply
Replacement 12v DC power supply for all 500 Series cameras. Input: 90v-240v AC 50-60Hz.
Liquid Heat Exchanger
Provides up to 10C additional CCD image sensor cooling. For use in warm weather conditions.
Color Filter Wheel
Replacement five position color filter wheel. Ideal for quick change of additional filter sets. Accepts all standard 1.25" filters.
Recirculating Pump
Water recirculating pump for use with liquid heat exchanger - 115VAC. Twenty five feet of clear vinyl tubing included.
1.25" Nosepiece
1.25" nosepiece to T-Mount adapter. Optional
SLR Lens Adapter
Designed for full-size QSI "ws" cameras with T-Mount adapter. Available for Canon EOS and Nikon F lenses.
2" Nosepiece
2" nosepiece to T-Mount adapter. Standard on all 500 Series QSI cameras.
T-Mount Adapter
T-Mount adapter plate. Standard on all 500 Series QSI cameras.
MaxIm DL/CCD Version 4.5 Upgrade
Upgrade to MaxIm DL/CCD version 4.5 at the time of camera purchase and save substantially over the regular retail price.

C-Mount  Adapter
C-Mount Adapter plate. Fits all Slim body QSI 500 Series cameras. Not recommended for 540i.
C-Mount Type II Adapter
C-Mount Adapter plate. Fits all Medium body QSI 500 Series cameras. Not recommended for 540i

 Shopping Help
 Privacy Policy
 Terms of Use
 Contact QSI
Copyright 2006-2008 Quantum Scientific Imaging, Inc.   All Rights Reserved.