G0 and G1 cameras are very compact, lightweight and easy to operate. The user only needs to insert it into telescope focuser, plug the USB cable to the computer and it works.

Sensitivity is an important feature of any guider. It must provide images of guiding star(s) with sufficient S/N ratio in rather short time to ensure perfect guiding. The necessity to accumulate light for many tens of seconds or even minutes is often unacceptable for high quality guider. This is why the G1 cameras utilize sensitive Sony ICX CCDs.

• Sony EXview HAD CCDs have better than 50% quantum efficiency and low read noise.

• G0/G1 cameras support 16-bits digitization, significantly enhancing the dynamic range.

• Strong anti-blooming protection keeps even bright stars round, without blooming streaks.

• G0/G1 cameras also provide very fast readout—pixel digitization speed reaches 8 MPx/s in fast read mode.

• G0/G1 cameras ensure very low readout noise.

Both G0 and G1 series of CCD cameras contain similar electronics, same CCD detectors and provide similar functionality. The difference is mainly in mechanical construction and in cooling.

• G0 cameras offer round body, which is more compact compared to G1 series, which could be important e.g. in combination with Off-Axis Guider etc.

• G1 cameras are slightly bigger and heavier, but they keep the CCD detector on lower temperature thanks to embedded fan, which more than two times lowers detector dark current. They also offer CS-thread adapter and also other alternatives of lens adapters (Canon EOS and Nikon bayonets, T-thread etc.).

G0 and G1 cameras do not require any external power supply, they are powered entirely from the host computer through the USB cable. Because the power provided by USB line is rather limited, these cameras do not use energy-hungry Peltier cooler. G1 cameras contain small fan, which helps keeping the CCD temperature on the environment temperature to significantly reduce dark current.

• G0 and G1 cameras are USB-powered devices (only 1 cable is necessary to operate).

• Absence of the Peltier cooler does not allow CCD operation temperature below ambient temperature, but fan embedded in G1 cameras keeps the CCD temperature very close.

Although modern astronomical telescope mounts support guiding through PC connection, G0 and G1 cameras incorporate standard 6-pin connector for the mount autoguider input. Thus the computer can guide the mount through the camera even in the case there is no link between the telescope mount and the PC.

• The G1 camera head is equipped with standard Autoguider connector.

  

  USB and Autoguider ports on G0 and G1 cameras

  Remark:

  The autoguider port current must not exceed 150 mA. If the mount does not treat the autoguider port as “logical input” only, but switches the guiding motors directly by these signals, a “relay box” must be inserted between the camera and the mount. The relay box ensures switching of currents required by the mount.

• SIPS (Scientific Image Processing System) control software supports both guiding through the camera port as well as through PC-to-telescope link.

The Autoguider port on the G0 or G1 camera head follows the standard pinout introduced by the ST-4 guiding camera:

G0 and G1 series of CCD cameras is intended for guiding as well as for CCD imaging, they are very capable to capture astronomical or microscopic images. G1 cameras can be used with any telescope or C/CS-mount compatible lens.

• The SIPS control software treats any CCD camera as imaging device or guider. User choose which camera will be used for imaging and which will be used for guiding.

  

  SIPS CCD Camera tool allows selection of any connected camera as imaging or guiding device

G0 series of CCD cameras include the following models. The letter C indicates the CCD with color mask is used, which enables acquiring of color images in single exposure.

G1 series of CCD cameras currently include the following models. The letter C indicates the CCD with color mask is used, which enables acquiring of color images in single exposure.

While the monochrome CCD captures all incoming wavelengths (to which the detector is sensitive) by all pixels, color CCD detector has red, green and blue filters applied on individual pixels, arranged to so-called Bayer mask. Monochrome CCD is substantially more sensitive, but it is necessary to perform multiple exposures through color filters if we want to capture color image. Color detector on the other side limits the incoming light by color filters, but enables reconstruction of color image from single exposure, even if the color resolution is lower than is the CCD pixel matrix.

Although the so-called Full Frame (FF) CCDs reach maximal sensitivity, they can be used only in conjunction with mechanical shutter. The so-called Interline Transfer (IT) CCDs are equipped with electronic shutter, allowing very short exposures, on the other side. This is why the G1 cameras use IT detectors. Also IT sensors differ by means of image read—while the progressive read chips can read all image pixels at once, interlaced read CCDs divide the frame to two half-frames containing only odd or only even rows and read the independently.

More information about CCD chip architecture can be found in the Introduction to the CCD Imaging article on our web site.

G0 and G1 guider cameras are designed to work in cooperation with a host Personal Computer (PC). The guiding algorithms are performed by a PC, not by the camera itself. To operate the camera, you need a computer which:

1. Is compatible with a PC standard.

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

   Remark:

   Drivers for Linux operating systems is also available. Contact the manufacturer if you are interested in Linux drivers.

3. Provides at last one free USB port.

   Remark:

   The current G0 and G1 series of CCD 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.

G1 Cameras Technical Specifications

CCD Chip

G0 and G1 cameras use sensitive and low noise Sony ICX CCD detectors. Sony does not publish the absolute quantum efficiency of these CCDs, but the estimated QE exceeds 50 %. The dark current and read noise of these CCDs are very low.

Model G0-0300 and G1-0300

G0-0300 and G1-0300 model uses VGA (640 × 480 pixels) Sony ICX424AL CCD chip with progressive read.

Model G0-0300C and G1-0300C

G0-0300C and G1-0300C model uses VGA (640 × 480 pixels) Sony ICX424AQ CCD chip with applied RGBG Bayer mask. Other specifications equal to monochrome ICX424AL CCD chip

Model G1-0301

G1-0301 model uses VGA (640 × 480 pixels) Sony ICX414AL CCD chip with progressive read.

Model G1-0301C

G1-0301C model uses VGA (640 × 480 pixels) Sony ICX414AQ CCD chip with applied RGBG Bayer mask. Other specifications equal to monochrome ICX414AL CCD chip

Model G0-0800 and G1-0800

G0-0800 and G1-0800 model uses XGA (1024 × 768 pixels) Sony ICX204AL CCD chip with progressive read.

Model G0-0800C and G1-0800C

G0-0800C and G1-0800C model uses XGA (1024 × 768 pixels) Sony ICX204AK CCD chip with applied RGBG Bayer mask. Other specifications equal to monochrome ICX204AL CCD chip

Model G1-1200

G1-1200 model uses HD (1280 × 960 pixels) Sony ICX445ALA CCD chip with progressive read.

Model G1-1200C

G1-1200C model uses HD (1280 × 960 pixels) Sony ICX445AQA CCD chip with applied RGBG Bayer mask. Other specifications equal to monochrome ICX445ALA CCD chip

Model G1-1400

G1-1400 model uses SXGA (1280 × 1024 pixels) Sony ICX285AL CCD chip with progressive read.

Model G1-1400C

G1-1400C model uses SXGA (1280 × 1024 pixels) Sony ICX285AQ CCD chip with applied RGBG Bayer mask. Other specifications equal to monochrome ICX285AL CCD chip

Model G0-2000 and G1-2000

G0-2000 and G1-2000 model uses UXGA (1600 × 1200 pixels) Sony ICX274AL CCD chip with progressive read.

Model G0-2000C and G1-2000C

G0-2000C and G1-2000C model uses UXGA (1600 × 1200 pixels) Sony ICX274AQ CCD chip with applied RGBG Bayer mask. Other specifications equal to monochrome ICX274AL CCD chip

Camera Electronics

16-bit A/D converter with correlated double sampling ensures high dynamic range, in fact exceeding the pixel well capacity of the CCD. Fast USB interface ensures image download time within fractions of second.

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.

Notes:

1. SIPS control software allows applying software binning if lower resolution images are desired.

2. Download times are valid for USB 2.0 host and may vary depending on host PC. Download times can be significantly longer when connected to USB 1.1 host.

3. Some electronics characteristics like system gain or system read noise cannot be determined without knowledge of some CCD parameters (e.g. output node sensitivity), which are not published by Sony.

Chip Cooling

The G0 and G1 series of CCD cameras does not use active cooling with Peltier TEC modules, so the CCD cannot be cooled below ambient temperature.

Working electronics (including the CCD chip itself) produce quite amount of heat, which rise the camera internal temperature many degrees above ambient temperature. Because the CCD thermal noise typically doubles every 5 or 7 °C, the thermal noise can be two or more times higher after some time of camera operation.

The G1 series of CCD cameras contain small fan, which efficiently removes the heat from the camera body and keeps the CCD temperature as close to ambient temperature as possible. The fan can be controlled from the software.

G0 as well as G1 cameras also include the embedded temperature sensor, which measures the current CCD temperature. This feature enables controlling of the CCD temperature and ensuring the used dark frame was taken in the same or similar temperature as the light exposure etc.

Power supply

G0 and G1 cameras are powered from the USB cable. No external power supply is necessary.

The current limit for single USB device is 500 mA from 5 V supply. The current required by G0 and G1 cameras varies depending on the camera operation mode. The following table summarizes camera consumption. Either way, cameras do not reach the allowed 500 mA limit, defined in USB specification.

Notes:

1. If the camera is connected through unpowered USB hub, the current available for the connected devices can be as low as 100 mA, which is insufficient. Always use powered USB hubs when using G1 cameras.

2. Note the so-called “active USB extender cable” is in fact nothing more than standard USB cable with a hub with single USB connector on the far side. Such hub consumes some energy and may not work with G1 cameras.

3. Some USB cables incorporate very thin power lines with relatively high resistance. If the USB device consumes several hundreds milliamperes, the voltage drop on such cable can be around one volt. Although the G1 camera should work, some features may be negatively affected. Always make sure the used USB cable is as short as possible and with low-resistance power lines.

G0 Camera Mechanical Specifications

Cylindrical camera head has 40 mm in diameter and is 85 mm long, from which 18 mm is 1.25" (31.7 mm) adapter and 67 mm is the camera body itself. The head is CNC-machined from high-quality aluminum and black anodized.

G0 cameras use Interline Transfer CCDs and they do no contain mechanical shutter. It is necessary to cover the telescope manually to take dark or bias frame.

Notes:

1. 1.25" adapter is integral part of the G0 camera body and cannot be removed and replaced by some other adapter.

G1 Camera Mechanical Specifications

Compact and robust camera head measures only 83 × 76 × 26 mm (approx. 3.25 × 3 × 1 inch). The head is CNC-machined from high-quality aluminum and black anodized.

The head contains CS or C-thread for connecting various CS or C lenses. The C-thread to 1.25" adapter can be screwed into the head to attach the camera to any telescope focuser accepting standard 1.25" eyepieces.

The G1 cameras use Interline Transfer CCDs and they do no contain mechanical shutter. It is necessary to cover the telescope manually to take dark or bias frame.

Notes:

1. Camera dimensions do not include the CS-thread adapter. This adapter depth is 6.4 mm, so the camera depth including the CS-thread adapter is 32.4 mm.

Guiding

Although the CCD cameras of G0 and G1 series are capable to capture images of various objects in astronomy, microscopy or in other applications of low-light conditions imaging, they are primarily intended as telescope mount guiders for scientific-grade G2, G3 and G4 and also for other imaging devices.

The G0 or G1 camera can work as “remote guider head” for any CCD camera, including the Gx series. The fact that it is not connected to the Gx camera head itself by some proprietary cable, but directly to the USB port of host PC, brings numerous advantages:

• Guiding can guide any camera or DSLR, not only the main camera type for which it is designed, like other remote guiding heads.

• There are no proprietary connectors/cables used to connect main camera with remote head. Standard USB cable is used instead.

• There is almost no limit in distance between guiding and imagine cameras. Guider can be placed to any guiding scope or to off-axis guider.

• Even if the guiding camera shares the same telescope with the main camera using off-axis guider, the light feeding the guider is deflected before it pases through the filters. So there is enough light for guiding even when the main imaging camera takes exposure through some very “dark” filters, like UV, Blue or Hα.

On the other side, simple USB hub creates an integrated solution from the pair of two separate Gx and G0 or G1 cameras.

The G0 or G1 guider camera is connected directly to the USB port of the host PC or to USB hub, it requires no “CPU box” or similar device. The guiding algorithms are performed in the PC itself. Because the typical CPU used in a PC is several orders of magnitude more powerful than any embedded CPU, which can be used in any CCD camera, guiding algorithms can be very sophisticated. Such algorithms are implemented in the SIPS camera control software.

There are two algorithms used in SIPS for guiding:

• Single star guiding. The PC calculates the centroid of the brightest star on the image acquired by the guider. The centroid position is calculated to the fraction of pixel precision, so the guiding can be very precise even when the guider is connected to short focal length telescope.

• Astrometric reduction guiding. The PC performs basically the same operation like in the case of sub-pixel matching of multiple exposures or astrometry reduction. Number of triangles are created from the brightest stars and they are matched to triangles on reference frame.

  Although triangle matching requires at last three stars on the guiding image and thus is suitable either for short-focus guiders or for rich star fields, the image shift is calculated from multiple star positions and is less sensitive to random errors like seeing, radiation spikes etc.

The guiding support in SIPS allows incorporating of G0 or G1 camera Autoguider port, which is de-facto standard and compatible with various autoguiders/telescope mounts. SIPS can also guide through telescope link (e.g. through the Meade LX-200 or Celestron Nexstar protocol) so no autoguider cable may be necessary. But the specialized device like G1 guider camera can usually control the mount with much better precision compared to relatively limited time resolution of an application running on the standard PC.

Image Gallery

Example images captured with G0 and G1 cameras.

All images published with permission of their respective authors.