QSI 6120 12mp Monochrome
Cooled CCD Camera

Next Generation Sony 12mp sensor with Peak QE of 77%

• 12 megapixel Sony ICX834 sensor
• 3.1µm pixel provides high resolution
• High Speed USB 2.0 and read rates up to 8 MHz

• 2-Stage TEC w/ cooling to 40°C below ambient
• Electronic shutter w/ exposures to 100µsec
• Available mechanical shutter
• Available 5 or 8-position color filter wheel
• Available Integrated Guide Port
• Broad Software support
• ASCOM-compatible Windows COM API
• Linux drivers and API 

The QSI 6120 model camera employs an 12mp Sony CCD image sensor. This new generation of Sony sensor offers remarkable sensitivity with peak QE of over 75%. The high senstivity, wide dynamic range, dual read rates, low noise performance and internal 5 or 8-position color filter wheels make the QSI 6120 ideally suited to a broad range of demanding scientific, medical, astronomical, and industrial imaging applications.

The QSI 6120wsg is available with an Integrated Guider Port (IGP) allowing astronomers to guide using the light from the main telescope while picking off the light from the guide star in front of the filters.

The 6120 camera system is supported by industry leading astronomy and microscopy image acquisition software plus a full camera control API is available for creating custom Windows or Linux applications.

Electronic Shutter
 
The QSI 6120 utilizes the electronic shutter built into the Sony ICX834 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 6120s model incorporates the optional internal, even-illumination mechanical shutter in the ‘mid-size’ camera body configuration. When operating with an interline transfer CCD, the 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.

Filter Wheel   

The Model 6120ws adds an internal five position filter wheel to the camera in a ‘full-size’ camera body. The 6120ws-8 incorporates a larger 8-position filter wheel. Even with the large 4mp sensor, the short backfocus and close spacing provided by the internal color filter wheel allows the 6120ws or ws-8 to work even with optics faster than f/2.8 with no vignetting. The filter wheel accepts any standard threaded 1.25″ or unmounted 31mm filters. 

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.

CCD Cooler Subsystem
 
Key in the compact design of the 600 Series cameras is a very efficient custom 2-stage thermoelectric cooler (TEC) 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 up to 45°C below ambient utilizing 85% power. Tight +/- 0.1°C temperature regulation is maintained at temperature settings 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 55°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 increase heat conduction and eliminate the possibility of frost forming inside the chamber. 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, gas-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 photo-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. Sony ExView CCD sensors accumulate thermal electrons at a rate of roughly 0.002 electrons per second per pixel at -10°C. Where a 10 minute exposure might generate 2000 thermal electrons at 25°C, it will produce only about 1 at -25°C, making noise from thermal current insignificant even on very long exposures.

Integrated Guider Port

Selecting the best guiding solution for deep sky imaging has always required a compromise. The available Integrated Guider Port (IGP) 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 600 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 internal 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 alwayshave all the star’s light available for guiding.

Integrated Guide Port 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 Integrated Guide Port (IGP) built into 600 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.

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.

Model 6120 CCD Image Sensor Specifications

Feature	Standard
CCD Manufacturer & Model	Sony ICX834
CCD Architecture	Interline Transfer
Microlens	Yes
Anti-blooming	Yes – 800x suppression
Imager Size: (WxH)	13.2mm x 8.8mm
Pixel Array (WxH):	4250 x 2838 active (12 megapixels)
Pixel Size:	3.1µm x 3.1µm
	Typical Values
Absolute Quantum Efficiency	Peak: 77% at 560nm
Pixel Dark Current	<0.002 electrons per second at -10°C
Intrinsic Read Noise	<4 electrons RMS (typically 3.5e- RMS)
Dynamic Range	68db

 

Model 6120 Camera Specifications  

Feature	Model 6120i		Model 6120s		Model 6120ws(-8)
CCD Image Sensor	Sony ICX834
Electronic Shutter	100µsec to 240 minutes		100µsec to 240 minutes		100µsec to 240 minutes
Mechanical Shutter	No		Yes		Yes
Internal Color Filter Wheel	No		No		ws    – 5-Position CFW ws-8 – 8-position CFW Holds 1.25″ or opt. 31mm filters
Camera Body Configuration	Slim Encl.		Med. Encl.		Full Encl.
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)		5-pos, W4.45” x H4.45” x D2.50” 8-pos, W5.86” x H5.56” x D2.50” (add 0.225″ for T-Mount)
Weight, without Nosepiece	26 oz. /  740g		34 oz.  /  950g		5-pos, 40 oz.  /  1130g 8-pos, 51 oz.  /  1450g
Optical Back Focus (w/o Filters in path)	0.58″ w/ T-mount adapter 0.68″ w/ C-mount adapter 0.35″ w/ no adapter		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 40°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
Read Rate	User Selectable High Quality mode at 800KHz, High Speed mode at 8MHz
Camera Gain	User Selectable High Gain 0.13 e-/ADU (default), Low Gain 0.28 e-/ADU
Digital Resolution	16 bits (both High Quality and High Speed mode)
Total System Read Noise	<4 electrons RMS (typically <3.5 e- RMS, CCD specification limited) in High Quality mode Typically <7 electrons RMS (CCD specification limited) in High Speed mode
Pixel Dark Current	<0.002 electrons per second at -10°C
Full Image Read and Download Time	Typically <16 second (host computer dependent) in High Quality Mode (800KHz) Typically <2 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 (See API Reference Manual for details)
T Mounting Adapter	Standard – T-Thread, 42mm x .75mm pitch
C Mounting Adapter (1″ x 32TPI) (Not recommeded for 540i)	Optional, C-Mount (Type I) lens focus compatible  (17.5mm backfocus)		Optional, C-Mount (Type II) lens focus compatible  (17.5mm backfocus)		Optional, for non-lens adapters and accessories  (standard C-Mount lens does not reach focus at infinity)
Nosepiece	Standard, T-Adapter to 2″ nosepiece Optional, T-Adapter  to 1.25″ nosepiece

 

Additional Model 6120wsg(-8) Camera Specifications  

Feature	QSI 600 Series wsg(-8)
Camera Body Configuration	Integrated Guider Port  Enclosure
Dimensions	5-pos wsg,    W4.45” x H5.0” x D3.08” 8-pos wsg-8, W5.86” x H6.1” x D3.08” (add 0.225″ for T-Mount, 0.35″ for 2.156″ thread mount)
Weight, without Nosepiece	5-pos, 46 oz.  /  1300g 8-pos, 56 oz.  /  1600g
Optical Back Focus (without Filters in path)	2.10″ (53.3mm) with 2.156″ thread adapter (optional) 1.98″ (50.2mm) with T mounting adapter 1.75″ (44.5mm) w/o mounting adapter
Guide Camera Attachment	T-mount (42mm x 0.75mm) w/built-in manual rotator  C-mount (1″ x 32 tpi) w/built-in manual rotator
Guide Camera Optical Focal Depth	12.5mm +/- 1.5mm (0.49″ +/- 0.06″)
Face Plate Adapter	Standard adapter – T-mount (2.156″ x 24tpi adapter available)
Nosepiece	Standard T-mount to 2″ nosepiece.  Optional 2″ nosepiece for 2.156 adapter