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Main page  Products  CCD cameras  Articles

Large format G4-9000 and G4-16000 cooled CCD cameras
 Cooled CCD cameras of G4 series contain detectors with 36 × 36 mm area, which is 50% more than photographic “full-frame” format. G4 camera dimensions are the same like dimensions of G3 series, with the exception of camera head thickness—G4 cameras are somewhat slimmer, because they do not contain internal filter wheel. Also camera handling, software control, power supply and connection to the host PC using fast USB 2.0 interface is the same like in the case of G3 cameras. Filter wheel for 50 × 50 mm square filters (round filters of 50 mm diameter cause vignetting on such large CCD chips) cannot be placed inside the camera head due to limited space. But it is possible to connect external filter wheel for 5 large filters to the G4 camera, the camera head already contains connector for external filter wheel control.

G4 cameras contain Full-Frame CCD chips OnSemi KAF with 36 × 36 mm detector area. These detectors are equipped with so-called “anti-blooming gate” (ABG), which drains the over-abundant charge from saturated pixels. ABG ensures the round images of bright stars, without disruptive blooming spikes. On the other side, compromising of the CCD linearity by ABG is only negligible. G4 cameras can be used for astrometric and photometric applications as well as for astrophotography.

No matter if your target is reliable scientific data or beautiful images of deep-sky objects, G4 CCD cameras are able to provide both.

G4-16000 CCD camera head

G4-16000 CCD camera head

G4 series contains the following camera models:

Model Color mask CCD chip Resolution Pixel size Image area Download time
G4-9000 no KAF-09000 3056 × 3056 12 × 12 μm 36.7 × 36.7 mm ~ 12.5 s
G4-16000 no KAF-16803 4096 × 4096 9 × 9 μm 36.9 × 36.9 mm ~ 22 s

G4 CCD cameras are designed to work in cooperation with a host Personal Computer (PC). As opposite to digital still cameras, which are operated independently on the computer, the scientific slow-scan, cooled cameras usually require computer for operation control, image download, processing and storage etc. To operate G4 CCD camera, you need a computer which:

  1. Is compatible with a PC standard.

  2. Runs a modern 32 or 64 bit Windows operating system.

  3. Provides at last one free USB port.

    Remark:

    The current series of G4 cameras are designed to operate with USB 2.0 high-speed (480 Mbps) hosts. Although they are fully backward compatible with USB 1.1 full-speed (12 Mbps) hosts, image download time can be somewhat longer if USB 1.1 connection is used.

G4 CCD Cameras Technical Specifications

CCD chip

G4 cameras use OnSemi Full-Frame CCD detectors with ABG (anti-blooming gate), ensuring images without excessive charge leaks from the overexposed portions of the image (blooming), e.g. bright stars in the field of view. ABG of these CCDs is designed for relatively low light levels (100× of saturation signal, compared to e.g. 300× of saturation signal ABG level of KAI-4022 CCD or 1000× of saturation signal ABG level of KAF-8300 CCD, intended for taking of images against sun etc.). Low ABG level does not to disrupt linear response to light.

CCD chip with 4096 × 4096 pixels resolution and 36 × 36 mm area for G4-16000 camera

Model G4-9000

G4-9000 model uses 9 MPx OnSemi KAF-09000 CCD.

Resolution 3056 (H) × 3056 (V) pixels
Pixel size 12 μm (H) × 12 μm (V)
Image area 36.7 mm (H) × 36.7 mm (V)
Full well capacity ~110,000 e-
Dark current 5 e-/s/pixel at 25 °C
Dark signal doubling temperature 7 °C

KAF-09000 CCD specifications

KAF-09000 CCD and its quantum efficiency

Model G4-16000

G4-16000 uses 16 MPx OnSemi KAF-16803 CCD.

Resolution 4096 (H) × 4096 (V) pixels
Pixel size 9 μm (H) × 9 μm (V)
Image area 36.9 mm (H) × 36.9 mm (V)
Full well capacity ~100,000 e-
Dark current 3 e-/s/pixel at 25 °C
Dark signal doubling temperature 6.3 °C

KAF-16803 CCD specifications

KAF-16803 CCD and its quantum efficiency

Camera Electronics

16-bit A/D converter with correlated double sampling ensures high dynamic range and CCD chip-limited readout noise. Fast USB interface ensures image download time within several tens of seconds.

Maximum length of single USB cable is 5 m. This length can be extended for instance to 10 m by using single USB hub or USB active extender cable. Up to 100 m extension can be achieved with third-party extender.

ADC resolution 16 bits
Sampling method Correlated double sampling
Read modes Standard (STD)
  Low-noise (LN)
Horizontal binning 1 to 4 pixels
Vertical binning 1 to 4 pixels
Sub-frame readout Arbitrary sub-frame
Computer interface USB 2.0 High Speed
  USB 1.1 Full Speed compatible

Camera electronics specifications

Image download time depends on the CCD chip used in particular camera model. Also the read noise depends on the chip as well as on the read mode.

  • Standard read mode provides system read noise approx. 1 e- above CCD chip read noise.

  • LN (Low-noise) read mode is somewhat slower (approx. 1.2×), but ensures system read noise equal or smaller than the manufacturer-specified chip read noise.

Model G4-9000

Gain 1.5 e-/ADU (1 × 1 binning)
  1.7 e-/ADU (other binnings)
System read noise 7 e- RMS (LN read)
  8 e- RMS (standard read)
Full frame download 15.7 s (LN read)
  10.9 s (standard read)

G4-9000 electronics specification

The gain in binning modes of G4-9000 cameras was adjusted from 2.5 e-/ADU to 1.7 e-/ADU beginning with system driver version 2.3 to utilize the full A/D converter dynamic range, because particular detector output node cannot pass higher output signal levels either way.

Model G4-16000

Gain 1.6 e-/ADU (all innings)
System read noise 9 e- RMS (KN read)
  10 e- RMS (standard read)
Full frame download 27.8 s (KN read)
  19.2 s (standard read)

G4-15000 electronics specification

G4-16000 cameras use the same gain for unbind and binned reading when used with system driver version 2.3 and higher. When older driver is used, stated gain 1.6 e-/ADU is used for 1×l binning only, while all other binning use 2.7 e-/ADU. Gain setting was unified to utilize the full A/D converter dynamic range, because particular detector output node cannot pass higher output signal levels either way.

Notes:

  1. Binning can be combined independently on both axes

  2. ULN read noise depends on the CCD chip itself. If the read noise of the particular chip is 7.5 e- RMS, the system read noise is also 7.5 e- RMS.

  3. Download times can be somewhat longer when connected to USB 1.1 host.

Power and USB connectors on the back side of the camera head. External filter wheel connector in the middle.

Power and USB connectors on the back side of the camera head. External filter wheel connector in the middle.

Warning:

External filter wheel connector on the camera head is of RJ-45 type, which is commonly used for Ethernet network interface. But the G4 camera is not equipped with Ethernet interface, it cannot be directly connected to Local Area Network. It is necessary to use embedded PC, which communicates with camera over USB and provides data to clients using TCP/IP (including WWW interface).

Chip Cooling

Regulated two-stage thermo-electric chip cooling up to 40 °C below ambient temperature with forced air cooling and 0.1 °C temperature precision ensure very low dark current for long exposures.

CCD chip cooling Thermoelectric (Peltier modules)
TEC modules Two stages
Max. delta T 45 °C below ambient maximum
  40 °C below ambient typical
Regulation precision 0.1 °C
Hot side cooling Air cooling (two 50 mm fans)
  Alternatively liquid cooling exchanger can be used

Chip cooling specifications

Air (left) and liquid (right) cooling of Peltier hot side

Notes:

  1. It is not recommended to cool the chip to the maximum temperature difference, else the camera cannot guarantee temperature stability when the ambient air temperature rises. It is usually practical to set the temperature so the cooling utilization varies around 90%. This provides enough reserve in cooling power to keep the CCD temperature even if the ambient temperature rises several degrees Celsius.

  2. The cooling performance depends on the environmental conditions and also on the power supply. If the power supply voltage drops below 12 V, the maximum temperature difference is lower.

  3. Camera construction does not allow usage of both air and liquid cooling. Combined cooling (air with the liquid cooling option) is not available, because such cooling does not work effectively enough with air only nor with water only.

Power supply

The 12 V DC power supply adapter enables camera operation from arbitrary power source including batteries, wall adapters etc. Universal 100–240 V AC/50–60 Hz, 60 W “brick” adapter is supplied with the camera. Although the camera power consumption does not exceed 30 W, the 60 W power supply ensures noise-free operation.

Camera head supply 12 V DC
Camera power consumption 14 W without cooling
  50 W with 100% cooling
Adapter input voltage 100-240 V AC/50-60 Hz
Adapter output voltage 12 V DC/5 A
Adapter maximum power 60 W

Power supply specifications

Notes:

  1. Camera power consumption is measured on the AC outlet (230 V/50 Hz) of the 12 V power supply.

  2. The camera contains its own power supplies inside, so it can be powered by unregulated 12 V DC power source—the input voltage can be anywhere between 10 and 14 V. However, some parameters (like cooling efficiency) can degrade if the supply drops below 11 V.

  3. G4 CCD camera measures its input voltage and provides it to the control software. Input voltage is displayed in the Cooling tab of the CCD Camera control tool in the SIPS. This feature is important especially if you power the camera from batteries.

12 V DC/5 A power supply adapter for G4 Camera

12 V DC/5 A power supply adapter for G4 Camera

Warning:

The power connector on the camera head uses center-plus pin. Although all modern power supplies use this configuration, always make sure the polarity is correct if you use own power source.

Mechanical Specifications

Compact and robust camera head measures only 154 × 154 × 65 mm (approx. 6 × 6 × 2.5 inches). The head is CNC-machined from high-quality aluminum and black anodized. The head itself contains USB-B (device) connector, 8-pin RJ45 connector for external filter wheel and 12 V DC power plug, no other parts (CPU box, USB interface, etc.), except a “brick” power supply, are necessary. Integrated mechanical shutter allows streak-free image readout, as well as automatic dark frame exposures, which are necessary for unattended, robotic setups.

Filter wheel if not integrated into camera head, it is necessary to use external filter wheel with 5 positions for 50 × 50 mm square filters. This external filter wheel is driven by the electronics already included into G4 camera head. Only single short 8-wire cable connects the filter wheel with the camera head and no separate power or communication cables are necessary for the external filter wheel. Also software (camera drivers, image acquisition applications) does not distinguish between internal and external filter wheel, camera works the same way like the G2 or G3 camera with integrated filter wheel.

Internal mechanical shutter Yes, blade shutter
Shortest exposure time 200 ms
Longest exposure time Limited by chip saturation only
Internal filter wheel no
Head dimensions 154 mm × 154 mm × 65 mm
Back focal distance 16.5 mm (without filter wheel)
  33.5 mm (with external filter wheel)
Weight of camera head 1.6 kg (without filter wheel)
  2.5 kg (with “M” external filter wheel)
  2.8 kg (with “L” external filter wheel)

Mechanical specification

Notes:

  1. Back focal distance is “optical”, which means it calculates with refraction on the plan-parallel glass optical elements in the light path.

Mechanical dimensions and back focal distance of the G4 camera head

Optional accessories

Camera head can be combined with various accessories according to the requirements of the target application (optical system, used filters, guiding, etc.).

Telescope adapters

Large diagonal dimension of CCD detectors used in G4 cameras (52 mm) does not allow usage of common adapters, typically limited to 2 inches diameter (50.8 mm), like T-thread M42 × 0.75, M48 × 1 thread, Nikon bayonet etc. This is why G4 cameras are by default shipped with M68 × 1 threaded adapter.

Another alternative if Canon EOS photographic lens adapter, which has enough diameter not to cause significant vignetting. Adapter is designed for G4 cameras with external filter wheel, with which it keep the 44 mm back focal distance between bayonet front plate and CCD detector.

M68 × 1 thread adapter
Adapter with inner thread M68 × 1.

Canon EOS lens adapter
Standard Canon EOS bayonet adapter.

External Filter Wheels

Because large detectors if the G4 camera require large 50 × 50 mm filters, filter wheel cannot be placed inside the camera head and G4 cameras rely on external filter wheels only. There are two sizes of external filter wheels for G4 cameras available:

  • The “M” sized wheel for 5 square filters 50 × 50 mm.

  • The “L” sized wheel for 7 square filters 50 × 50 mm.

“M” (5-positions) and “L” (7-positions) External Filter Wheels for the G4 camera

Remark:

There is a possibility to use round D50 mm filters with the G4 camera. Normally these filters cause significant vignetting as the CCD diagonal measures 52 mm and filter clear aperture is 47 mm. But it the used optics does not cover the whole detector (e.g. standard camera fish-eye lens), D50 mm filters increase number of available position from 5 to 7 in the case of “M” wheels and from 7 to 9 in the case of “L” wheels.

External filter wheels for 5 filters 50 × 50 mm (left) and for 7 filters D50 mm or with M48 × 0.75 threaded cells (right)

External filter wheels are described in detail here.

Off-Axis Guider adapter

The G4 off-axis guider (OAG) is designed to allow attachment of any guiding camera with 1.25" eyepiece nose, although the nose must be somewhat shorter to achieve focus. G0 cameras are designed to achieve focus with G4 OAG and a special shorter version of 1.25" nose with C-mount thread is available for all G1 cameras. Any camera with CS-mount (short version of C-mount standard) can use this adapter to be attached to G4 OAG.

The G4 OAG offers the M68 × 1 thread on the telescope side. The back focal distance is 61.5 mm.

G4 Off-Axis Guider Adapter

Off-Axis Guider adapters are described in detail here.

Guiding cameras

G0 and G1 cameras are completely independent devices with their own USB connection to the host PC. They are mentioned here only not to omit an important part of the whole system.

G1-0301 standalone guiding/imaging camera is equipped with USB connection and standard “AutoGuider” port

G0 and G1 cameras can be used on the G4 OAG, on standalone guiding telescope or for any other imaging purpose, like Moon or planetary imaging etc. Both G0 and G1 camera can share the Gx Camera Ethernet Adapter with up to 3 other Gx cameras to be accessed over network.

G0 and G1 guider cameras are described in detail here.

Gx Camera Ethernet Adapter

Gx Camera Ethernet Adapter allows connection of up to 4 Gx cameras of any type on the one side and 1 Gbps Ethernet on the other side. This adapter allows access to connected Gx cameras using routable TCP/IP protocol over practically unlimited distance.

The Gx Camera Ethernet Adapter is available in several variants, but their functionality is basically the same

Gx Camera Ethernet Adapter devices are described in detail here.

Software Support

Powerful SIPS (Scientific Image Processing System) software supplied with the camera allows complete camera control (exposures, cooling, filters) with automatic sequences and complete image calibration. SIPS also supports advanced tools like Image Add tool with automatic sub-pixel image alignment, (L)RGB Add tool, Image Blink tool, image filters and many more functions.

Scientific Image Processing System

SIPS software package is freely available for download from this www site.

Drivers for ASCOM standard as well as native drivers for third-party software are also available (e.g. TheSkyX, MaxIm DL, AstroArt, etc.). Visit the download page of this web site for current list of available drivers, please.

Automatic guiding

SIPS software package allows automatic guiding of the astronomical telescope mounts using separate guiding camera. Proper and reliable automatic guiding utilizing the computational power of Personal Computer (e.g. calculation of star centroid allows guiding with sub-pixel precision) is not simple task. Guiding complexity corresponds to number of parameters, which must be entered (or automatically measured).

The SIPS Guider tool window

The SIPS “Guider” tool window

The “Guiding” tool allows switching of autoguiding on and off, starting of the automatic calibration procedure and recalculation of autoguiding parameters when the telescope changes declination without the necessity of new calibration. Also swapping of the German Equatorial mount no longer requires new autoguider calibration. There is also a graph showing time history of guide star offsets from reference position in both axes. The length of graph history as well as the graph range can be freely defined, so the graph can be adjusted according to particular mount errors and periodic error period length. Complete log of calibration procedure, detected offsets, correction pulses etc. is also shown in this tool. The log can by anytime saved to log file.

An alternative to classic autoguiding is the inter-image guiding, designed for modern mounts, which are precise enough to keep tracking with sub-pixel precision through the single exposure, and irregularities only appear on the multiple-exposure time-span. Inter-image guiding then performs slight mount position fixes between individual exposures of the main camera, which eliminates “traveling” of the observed objects through the detector area during observing session. This guiding method uses main imaging camera, it does not use another guiding camera and naturally does not need neither OAG nor separate guiding telescope to feed the light into it.

Inter-image guiding controls in the Guiding tab of the Imager Camera tool window

Inter-image guiding controls in the Guiding tab of the Imager Camera tool window

Shipping and Packaging

G4 CCD cameras are supplied in the foam-filled, hard carrying case containing:

  • Camera body with a user-chosen telescope adapter. The M68 × 1 adapter is included by default, Canon EOS adapter is available at additional cost.

  • A 100-240 V AC input, 12 V DC output “brick” adapter with 1.8 m long power cable.

  • 5 m long USB A-B cable for connecting camera to host PC.

  • A CD-ROM with camera drivers, SIPS software package with electronic documentation and PDF version of User's Manual.

  • A printed copy of camera User's Manual.

G3 and G4 CCD cameras are shipped in the foam-filled carrying case (left), larger case is used if camera is ordered with external filter wheel (right)

Image Gallery

Example images captured with G4 cameras.

Object M27 “Dumbbell” planetary nebula
Author Frédéric Lambert
Camera G4-16000 + EFW-L-7
Filters RGB + narrow-band Hα, OIII
Telescope Takahashi CCA 250 mm f/5

Object IC5067 nebula
Author Frédéric Lambert
Camera G4-16000 + EFW-L-7
Filters narrow-band Hα, SII, OIII
Telescope Officina Stellare UCRC 300

Object M31 Big Andromeda Galaxy
Author Frédéric Lambert
Camera G4-16000 + EFW-L-7
Filters RGB
Telescope Takahashi CCA 250 mm f/5

Object M33 galaxy in Triangulum
Author Frédéric Lambert
Camera G4-16000 + EFW-L-7
Filters RGB + narrow-band Hα
Telescope Takahashi CCA 250 mm f/5

Object NGC2244 “Rosette” nebula
Author Frédéric Lambert
Camera G4-16000 + EFW-L-7
Filters narrow-band Hα, SII, OIII
Telescope Officina Stellare UCRC 300

Object NGC6888 “Crescent” nebula
Author Frédéric Lambert
Camera G4-16000 + EFW-L-7
Filters narrow-band Hα, SII
Telescope Officina Stellare UCRC 300

Object NGC7635 “Bubble” nebula
Author Frédéric Lambert
Camera G4-16000 + EFW-L-7
Filters narrow-band Hα, SII, OIII
Telescope Takahashi CCA 250 mm f/5

Object IC1805 nebula
Author Laurent Bourgon
Camera G4-16000 + EFW-L-7
Filters narrow-band Hα, SII, OIII
Telescope Orion Optics/Skymeca 50 cm MDK f/6,8

Object NGC7635 “Bubble Nebula” in Cassiopeia
Author Laurent Bourgon
Camera G4-16000 + EFW-L-7
Filters narrow-band Hα, SII, OIII
Telescope Orion Optics/Skymeca 50 cm MDK f/6,8

Object IC63 nebula in Cassiopeia
Author Laurent Bourgon
Camera G4-16000 + EFW-L-7
Filters LRGB
Telescope Orion Optics/Skymeca 50 cm MDK f/6,8

Object NGC7380 “Wizadr Nebula” in Cepheus
Author Laurent Bourgon
Camera G4-16000 + EFW-L-7
Filters narrow-band Hα, SII, OIII
Telescope Orion Optics/Skymeca 50 cm MDK f/6,8

Object NGC7822 star forming region in Cepheus
Author Laurent Bourgon
Camera G4-16000 + EFW-L-7
Filters narrow-band Hα, SII, OIII
Telescope FSQ106ed

Object “North America” and “Pelican” nebulae
Author Laurent Bourgon and Didier Chaplain
Camera G4-16000 + EFW-L-7
Filters narrow-band Hα, SII, OIII a NII
Telescope FSQ106ed
Exposure 65 hours

Object M31 galaxy in Andromeda
Author Philippe Bernhard
Camera G4-16000 + EFW-L-7
Filters LRGB
Telescope RH200
Exposure 3 hours

Object NGC6960 “Veil” nebula
Author Laurent Bourgon
Camera G4-16000 + EFW-L-7
Filters narrow-band Hα, SII a OIII
Telescope Orion Optics/Skymeca 50 cm MDK f/6,8

Object NGC7000 mlhovina “Severní Amerika”
Author Michael Miller
Camera G4-16000 + EFW-L-7
Filters narrow-band Hα, SII a OIII
Telescope 152mm APM APO

Object NGC6960 “Veil” nebula
Author Michael Miller
Camera G4-16000 + EFW-L-7
Filters Astrodon LRGB
Telescope 152mm APM APO

Object M106 galaxy
Author Michael Miller, Warren Keller
Camera G4-16000 + EFW-L-7
Filters Astrodon LRGB
Telescope 152mm APM APO

Object NGC6992 “Veil nebula”
Author Michael Miller
Camera G4-16000 + EFW-L-7
Filters Astrodon LRGB
Telescope 152mm APM APO

Object M51 “Whirlpool” galaxy
Author Michael Miller
Camera G4-16000 + EFW-L-7
Filters Astrodon LRGB
Telescope 152mm APM APO

Object M16 “Eagle” nebula
Author Michael Miller
Camera G4-16000 + EFW-L-7
Filters Astrodon LRGB
Telescope 152mm APM APO

Object M16 “Eagle” nebula
Author Michael Miller
Camera G4-16000 + EFW-L-7
Filters H-alpha, OIII and SOII narrow-band
Telescope 152mm APM APO

Object M63 “Sunflower” galaxy
Author Michael Miller
Camera G4-16000 + EFW-L-7
Filters Astrodon LRGB
Telescope 152mm APM APO

Object “North America” and “Pelican” nebulae
Author Petr Novak
Camera G4-16000 + EFW4-5
Filters 12nm H-alfa
Telescope Takahashi FSQ 106 ED

Object M31 Great Andromeda Galaxy
Author Pavel Cagas (data acquisition), Martin Myslivec (image registration)
Camera G4-16000 (cropped to 3k × 3k pixels)
Filters Astronomik LHaRGB
Telescope Orion SPX 250 + Paracorr

Object “North America” and “Pelican” nebulae
Author Martin Myslivec
Camera G4-16000
Telescope Borg 66 ED

Object M81 “Boode galaxy” and M82 “Cigar galaxy”
Author Pavel Cagas
Camera G4-16000 (cropped to 3k × 3k pixels)
Filters Astronomik LHaRGB
Telescope Orion SPX 250 + Paracorr

Object Field of variable star V729 Aql
Author Pavel Cagas, field composition Vaclav Pribik
Camera G4-16000 (cropped to 3k × 3k pixels)
Filters Clear
Telescope Orion SPX 250 + Paracorr

All images published with permission of their respective authors.

 
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