G3 and G4 CCD Operating Manual
Version 2.4 Modified on January 20th, 2014 All information furnished by Moravian Instruments is believed to be accurate. Moravian Instruments reserves the right to change any information contained herein without notice. G3 and G4 CCD cameras are not authorized for and should not be used within Life Support Systems without the specific written consent of the Moravian Instruments.
Table of Contents Introduction...............................................................................................5 Camera Technical Specifications.............................................................7 CCD Chip..........................................................................................10 Model G3-6300...........................................................................10 Model G3-1000...........................................................................
Camera LED state indicator........................................................36 Working with Multiple Cameras.......................................................36 Camera Operation...................................................................................38 Camera and the Telescope................................................................38 Temperature Control.........................................................................40 First Images........................................
Introduction Thank you for choosing the Moravian Instruments CCD camera. G3 and G4 series of CCD cameras were developed for imaging under extremely lowlight conditions in astronomy, microscopy and similar areas. Design of this series inherits from G2 cameras, with which they share precise electronics providing uniform frames without artifacts and extremely low read noise limited only by CCD detector itself. Also the robust construction, rich software support and easy manipulation are the same.
G3 and G4 cameras are designed to operate with USB 2.0 highspeed (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. A simple and cheap device called USB hub can expand number of available USB port. Typical USB hub occupies one computer USB port and offers four free ports. Make sure the USB hub is USB 2.0 high-speed compatible.
Camera Technical Specifications G3 and G4 series of CCD cameras are manufactured with two kinds of Truesense Imaging (formerly Kodak) CCD detectors: ● G3 and G4 cameras with Truesense Imaging KAF Full Frame (FF) CCD architecture. Almost all Full Frame CCD detector area is exposed to light. This is why these detectors provide very high quantum efficiency.
● G3 cameras with Truesense Imaging KAI Interline Transfer (IT) architecture (G4 cameras are not produced with IT detectors). There is a shielded column of pixels just beside each column of active pixels on these detectors. The shielded columns are called Vertical registers. One pulse moves charge from exposed pixels to shielded pixels on the end of each exposure. The the charge is moved from vertical registers to horizontal register and digitized in the same way like in the case of Full Frame detectors.
G3 and G4 camera models: Model G3-6300 G3-1000 G3-11000 G3-11000C CCD chip KAF-6303E KAF-1001E KAI-11002 KAI-11002 Resolution 3072×2048 1024×1024 4032×2688 4032×2688 Pixel size 9×9 µm 24×24 µm 9×9 µm 9×9 µm CCD area 27.7×18.4 mm 24.6×24.6 mm 36.3×24.2 mm 36.3×24.
These cameras are able to acquire color image in single exposure, without the necessity to change color filters. On the other side color mask brings lower sensitivity and limits the capability to perform exposures using narrow-band filters etc. Because each pixel is covered by one of three basic color filters, it is necessary to compute (interpolate) remaining two colors for each pixel, which of course limits resolution of color image.
Pixel size 9×9 µm Imaging area 27,7×18,4 mm Full well capacity Approx. 100 000 e- Output node capacity Approx. 220 000 eDark current 1 e-/s/pixel at 0°C Dark signal doubling 6.3 °C Model G3-1000 G3-01000 model uses 1 MPx Truesense Imaging KAF-1001E Class 1 or 2 CCD chip. Resolution 1024×1024 pixels Pixel size 24×24 µm Imaging area 24.6×24.6 mm Full well capacity Approx. 220 000 e- Output node capacity Approx. 650 000 eDark current 17 e-/s/pixel at 0°C Dark signal doubling 5.
Model G3-16000 G3-16000 uses 16 MPx CCD Truesense Imaging KAI-16070. Resolution 48883256 pixels Pixel size 7.47.4 µm Imaging area 36.224.1 mm Full well capacity approx. 26 000 e- Dark current (pixels) 0,3 e-/s/pixel at 0°C Dark current (V-registers) 33 e-/s/pixel at 0°C Dark signal doubling (pixels) 7 °C Dark signal doubling (V-registers) 9 °C Model G3-16000C G3-16000C uses 16 MPx CCD Truesense Imaging KAI-116070 with color (Bayer) mask.
Dark signal doubling 6,3 °C 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 seconds. Maximum length of single USB cable is 5 m. This length can be extended to 10 m by using single USB hub or active USB extender cable. Up to 5 hubs or active extenders can be used in one connection.
15 e- (Preview) Full frame download 9.8 s (Low noise) 8.1 s (Preview) Model G3-1000 Gain 3 e-/ADU (1×l binning) 5 e-/ADU (other binnings) System read noise 12 e- (Low noise) 15 e- (Preview) Full frame download 2.0 s (Low noise) 1.7 s (Preview) Model G3-11000 Gain 0.8 e-/ADU (1×l binning) 1.6 e-/ADU (other binnings) System read noise 11,5 e- (Low noise) 13 e- (Preview) Full frame download 16.9 s (Low noise) 14.1 s (Preview) Model G3-16000 Gain 0.4 e-/ADU (1×l binning) 0.
Full frame download 16.3 s (Low noise) 13.1 s (Preview) Model G4-16000 Gain 1.6 e-/ADU (all binnings) System read noise 9 e- (Low noise) 11 e- (Preview) Full frame download 26 s (Low noise) 22 s (Preview) System read noise depends on the particular CCD detector. For instance KAF-6303 can be read with 11 e- RMS. Download times are valid for USB 2.0 host and may vary depending on host PC. G4-16000 cameras use the same gain for unbinned and binned reading when used with system driver version 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 drop is lower. CCD chip cooling Thermoelectric (Peltier modules) TEC modules Two stages Maximal ∆T 45 °C below ambient 1) Regulated ∆T 1) Maximal ∆T2) Regulated ∆T 40 °C below ambient (~75% cooling) 40 °C below ambient 2) 35 °C below ambient (~75% cooling) Regulation precision ±0.
consumption 52 W maximum 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 connector 5.5 / 2.5 mm 1. Power consumption is measured on the AC side of the supplied 12 V AC/DC power supply. Camera consumes less energy from 12 V power supply than state here. 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.
Internal mechanical shutter Yes, blade shutter Shortest exposure time 0.2 s Longest exposure time Limited by chip saturation only Internal filter wheel (G3 cameras only) 5 positions 2" threaded filter cells or glass filters up to 51 mm diameter Head dimensions 154×154×77.5 mm (G3 with wheel) 154×154×65 mm (G3 without wheel, G4) Back focal distance 29 mm (G3 with wheel) 16,5 mm (G3 without wheel, G4) Camera head weight 1.7 kg (G3 with wheel) 1.
Illustration 5: Head of the G3 camera without internal filter wheel Illustration 6: G4 camera head 19
Package Contents G3 and G4 CCD cameras are supplied in the foam-filled, hard carrying case containing: ● Camera body with a user-chosen telescope adapter. The standard 2" barrel adapter is included by default for G3 cameras. G4 cameras are equipped with M68×1 threaded adapter. If ordered, the filter wheel is already mounted inside the camera head and filters are threaded into place (G3 cameras only).
long connection. Third-party USB extenders allow USB connection tens or even hundreds meters long. ● An USB Flash Driver or CD-ROM with camera system drivers, drivers for third party software packages, SIPS software package with electronic documentation and PDF version of this manual. ● A printed copy of this manual. Optional components Number of optional parts are available for G3 and G4 CCD cameras. These parts can be ordered separately. Refer to our web site for the pricing, please.
Clear (C) filter Optional clear filter (optical glass with AR coatings) of the same thickness like RGB filters can be used in addition to (or instead of) Luminance filter to use maximum chip QE for luminance images. Optical glass is used instead of simple empty hole in filter wheel to ensure proper focus and to eliminate refocusing when changing from filtered to unfiltered exposures.
T-thread long M42×0.75 mm inner thread, preserves 55 mm back focal distance as defined by Tamron. Pentax (Praktica) lens adapter M42×1 mm inner thread, preserves 45.5 mm back focal distance. M48×0.75 thread adapter Adapter with inner thread M48×0.75 Zeiss adapter M44×1 mm outer thread, includes fixing nut.
thread) cause vignetting with this large chip. E.g. TeleVue Paracorr PSB1100 with appropriate adapter must be used with KAI-11000 CCD. If the mounting standard defines also back focal distance (distance from adapter front plane to detector), the particular adapter is constructed to preserve defined distance (for instance T-thread defines back focal distance to 55 mm, but certain distance is defined also for Pentax (Praktica) thread, for Canon EOS and Nikon bayonets etc.).
M68×1 adapter Adapter with both inner and outer M68×1 thread Canon EOS lens adapter Standard Canon EOS bayonet adapter Adapters are attached to the camera body using four M3 (3 mm metric) screws. Threaded holes on the camera body are placed on the corners of 52 mm square. Custom adapters can be made upon request. G2 and G3 cameras use smaller 44 mm threaded hole square on the camera head for mounting adapters, so adapters for G2/G3 series and G4 series are not compatible.
Getting Started Although the G3 and G4 cameras are intended for operation at night (or for very low-light conditions at day), it is always better (and highly recommended) to install software and to make sure everything is working OK during day, before the first night under the stars.
connect it to the host PC using the included USB A-B cable. Windows detects new USB device and opens hardware installation wizard. The system driver installation is slightly different on different Windows systems. Due to differences in KAF and KAI CCD handling, there are two drivers for cameras utilizing the respective detectors. Driver names are distinguished by the last letter 'F' and 'I'. Also individual camera revisions may require different drivers depending on the used digital electronics.
Windows XP and Windows Vista System Driver Installation The operating system notifies the new USB device was plugged in the “Found new hardware bubble”. The system then opens the “Found New Hardware” Wizard. 1. The wizard offers searching for suitable driver on Windows Update site. Reject this offer (choose “No, not this time”) and click “Next” button. 2. Choose the “Install the software automatically” in the next step. Insert the CD-ROM into the drive and the wizard will continue by the next step.
folder. The package can be even run directly from USB Flash Drive or CDROM. SIPS needs the Microsoft Visual C++ 2008 libraries to work. These libraries are already installed on many Windows PCs, because they are used by a lot of other applications. But if they are not present, it is necessary to install them first. The best way how to do it is to run the “Microsoft Visual C++ 2008 SP1 Redistributable Setup” package (executable file 'vcredist_x86.exe').
SIPS configuration files The software package distinguishes two types of configuration: ● Global configuration, common for all users. ● User-specific configuration. Global configuration defines which hardware is used and which drivers controls it. The configuration is stored in the simple text file “SIPS.ini”, which must be placed in the same folder as the “SIPS.exe” main executable. The file may look for example like this: [Camera] Gx Camera on USB = gxusb.dll Gx Camera on Ethernet = gxeth.
file, beginning from the position and open state of individual tool windows, to the preferred astrometry catalog and parameters for searching stars in images. G3 and G4 CCD Camera Driver for SIPS SIPS is designed to work with any CCD camera, providing the driver for the particular camera is installed. The driver for G3 CCD camera is include into the basic SIPS package and is not necessary to install it separately. All Gx cameras use common driver 'gxusb.
Filters are described in the [filters] Section. Every line in this section describes one filter position. Filter description is a comma-separated list of three values: • Filter name: This name is returned to the client application, which can use it to list available filters in the filter wheel. • Filter color: This color can be used by client application to display the filter name with a color, hinting the filter type. The color can be expressed by a name (White, Red, LRed, etc.
Illustration 9: Filters offered by the CCD Camera tool If there are more filters in the camera than the configuration file describes, another filters will be added with undefined name. And if the configuration file describes more filters than the number of filter in the camera, last descriptions will be omitted. Using of multiple configuration files for different cameras It is sometimes necessary to work with multiple cameras, sharing single driver on the computer (whole series of Gx cameras share 'gusb.
directly in SIPS camera control tool, limiting camera resolution this way is not very convenient when multiple frames of different types (light, dark, flat) are acquired. If for instance the user wants to use only center area of a large CCD because the optics used cannot utilize such large CCD detector, it is possible to read only a sub-frame (sub-frame 512, 512, 3072, 3072 converts 16Mpx G4-16000 camera into 9MPx camera). But different subframe is used e.g.
cable. Illustration. 10: Power connector (right) and USB connector (left) on the bottom side of the camera head Note the computer recognizes the camera only if it is also powered. Camera without power act the same way as the unplugged one from the computer point of view. When the camera is powered and connected to the computer (with appropriate drivers installed), it starts to initialize filter wheel.
Camera LED state indicator There is a two-color LED on the camera body, close to the USB connector. The LED is functional only upon camera startup not to influence observations. The LED starts blinking orange when the camera starts to initialize filter wheel. Orange blinks are not always the same – they depend on the filter position when the camera is powered up.
Illustration 11: Camera Id number is displayed in brackets after camera name in SIPS But the user always needs to distinguish individual cameras – for instance one camera should be used for pointing, another for imaging. This is why every camera has assigned unique identifier (ID number). This number is engraved into on camera body and it is also displayed in the list of cameras in the CCD Camera tool in SIPS. This enables the user to select the particular camera.
Camera Operation Camera operation depends on the software used. Scientific cameras usually cannot be operated independently on the host computer and G3 and G4 CCD also needs a host PC (with properly installed software) to work. Camera itself has no displays, buttons or other controls. On the other side, every function can be controlled programmatically, so the camera is suitable for unattended operation in robotic setups. Plug the camera into computer and power supply and run the SIPS program.
connected. Standard 2" barrel adapter allows camera connection to vast majority of astronomical telescopes. 2" barrel adapter can cause vignetting (partial shielding of detector corners), especially if a fast optical systems is used with the G3-11000 camera with 24×36 mm CCD detector. Also T-thread (M42×0.75) or Praktica (M42×1) adapters cause even bigger vignetting. G3 cameras can use threaded adapter with 2.156-24UN thread, designed for TeleVue Paracorr PSB-1100 coma correctors (thread diameter is approx.
The following chapters provide only a brief description of camera operation under SIPS (Scientific Image Processing System) program, supplied with the camera. Refer to the SIPS User's Guide (click “Help” and “Contents” from the SIPS main menu) for thorough description of all SIPS features. Temperature Control Active chip cooling is one of the basic features of scientific CCD cameras (SIPS User's Guide explains why cooling is important to reduce thermal noise).
Illustration 13: “Cooling” tab of the CCD Camera Control tool Also notice the yellow line in the graph – it displays camera internal temperature. This temperature also somewhat grows as the cooling utilization grows. The hot air from the Peltier hot side warms up the camera interior slightly.
What is the best temperature for the CCD chip? The answer is simple – the lower the better. But the minimum temperature is limited by the camera construction. The G3 and G4 cameras are equipped with two-stage cooler, which can cool the chip more than 45 °C below ambient temperature with air cooling. But it is not recommended to use maximum possible cooling. If the environment conditions change, the camera may be unable to regulate the temperature if the environment air temperature rises.
It is necessary to define few parameters before the first shot. First, it is necessary to define the image type – choose “Light” from “Exposure” combo box. Then choose the exposure time. If you experiment with exposures in the dark room with a camera connected to some small refractor, start with 1 second. Do not forget to review the image handling options on the right side of the “Exposure” tab.
Open the “Histogram and Stretch” tool . Illustration 15: Histogram and Stretch tool The exact meaning of the histogram chart is explained in the SIPS software documentation. Now only try to play with “Low” and “High” count-boxes or better with the related horizontal sliders. Observe how the image view is changed when you alter these values. The best positions of Low and High control are as follows: the Low count should be on the count value representing black on the image.
effects of unevenly illuminated field, CCD thermal noise etc. significantly degrade image quality when imaging dim deep-sky objects for many minutes. This is why every CCD image should be calibrated. Image calibration basically consists of two steps: 1. Dark frame subtraction 2. Applying flat field Image calibration is supported by the “Calibration” tool in SIPS .
Illustration 17: The dark frame corresponding to the above raw image Illustration 18: The raw image with subtracted dark frame Subtraction of the dark frame eliminated majority of thermal noise, but unevenly illuminated field is still obvious. Image center background is much brighter than the border parts.
possible to distinguish which part of the nebula is emission (red) and which is reflection (blue). But astronomical cameras are only rarely equipped with color CCD chips from number of reasons. The color and monochrome chips are discussed in the SIPS User's Guide – refer to the “Introduction to CCD Imaging” chapter. Although the G3 camera is equipped with monochrome CCD chip, it is definitely capable to capture color images, at last when the internal filter wheel contains RGB filters.
sensitive to changes of color than to changes of brightness. This is why the CCD chip can be binned when capturing color images to 2×2 or 3×3 to significantly increase its sensitivity. Luminance image is taken without binning so the image resolution is not degraded. Let us note that imaging through separate color filters is close to impossible in some cases. For instance taking images of some fast evolving scenes, like planet occultation by Moon, imaging of fast moving comet etc.
Illustration 22: ...and a resulting image If we take images for individual colors and also luminance image, possibly with different binning and exposure times, the calibration starts to be relatively complex. We need dark frame for every exposure time and binning. We need flat field for every filter and binning. We need dark frames for every flat field. This is the price for beautiful images of deep-sky wonders.
Illustration 23: Schematic diagram of color CCD detector Every pixel receives light of particular color only (red, green or blue). But color image consists of pixels with all three colors specified. So it is necessary to calculate other color from the values of neighboring pixels. Covering pixels with such color mask and subsequent calculations of remaining colors was invented by Mr. Bayer, engineer working at Kodak company.
and no raw monochrome image is shown) or to perform this processing anytime later. Debayer processing can be performed from “Image Transform” tool (to open this tool click button in the tool-bar or choose “Image Transform” from the “Tools” menu). Check box “Debayer new images” allows immediate Debayer processing of images downloaded from the camera. The button performs Debayer processing of currently selected image. The Bayer mask displayed on the schematic image above begins with blue pixel.
mix pixels of different colors. Images must be Debayer processed first and then stacked. Balancing colors CCD chip sensitivity to red, green and blue light is different. This means the exposure of uniformly illuminated white surface does not produce the same signal in pixels covered with different color filters. Usually blue pixels gather less light (they have less quantum efficiency) then green and red pixels.
Illustration 24: Histogram and Stretch tool shows histograms of individual colors 53
Some General Rules for Successful Imaging Advanced CCD cameras caused a revolution in amateur astronomy. Amateurs started to capture images of deep-sky objects similar or surpassing the ones captured on film by multi-meter telescopes on professional observatories. While the CCD technology allows capturing of beautiful images, doing so is definitely not easy and straightforward as it may seems.
● Focus image properly. Almost unnoticeable focuser shift affects star diameter. Focusing, especially on fast telescopes, is critical for sharp images. Electrical focuser is a huge advantage, because it allows focusing without shaking the telescope by hand and with precision surpassing the manual focusing. Keep on mind that the star images are affected not only by focusing, but also by seeing. Star images will be considerably bigger in the night of poor seeing, no matter how carefully you focus.
first successful night out. Nights can become cloudy or foggy, the full Moon can shine too much, the seeing can be extremely bad… Number of things can come bad, but the bad luck never lasts forever. Start with bright objects (globular clusters, planetary nebulae) and learn the technique. Then proceed to more difficult dimmer objects.
Camera Maintenance The G3 CCD camera is a precision optical and mechanical instrument, so it should be handled with care. Camera should be protected from moisture and dust. Always cover the telescope adapter when the camera is removed from the telescope or put the whole camera into protective plastic bag. Desiccant exchange The G3 and G4 camera cooling is designed to be resistant to humidity inside the CCD chamber.
The silica-gel container is accessible from the back side of the camera head. Illustration 25: Silica-gel container is under the screwed cap with slot, left from the cooling fans The slotted desiccant chamber cap can be unscrewed e.g. by a coin. Pour out wet silica-gel and fill the chamber with a dry one. The desiccant container can be left open without the fear from contamination of CCD chamber interior by dust.
Warning: The blade shutter rotates 180° between individual snapshots. Camera cover could be opened only when the shutter is closed. If for instance the camera is unplugged from power adapter while exposing and the shutter remains open, it can be damaged while removing the camera cover. After removing the screws carefully turn the camera head by the telescope adapter upward. Gently pull the front part of the case.
Illustration 27: Filter positions in the G3 filter wheel Changing the Whole Filter Wheel The whole filter wheel can be changed at once. It is necessary to remove the front part of the camera case the same way as in the case of changing filters. The filter wheel can be removed when you unscrew the bolt on the center of the front part of camera case. Take care not to damage the horseshoe-shaped optical bar when replacing the filter wheel. Changing the Telescope Adapter The camera head contains bolt square.
Power Supply Fuse The power supply inside the camera is protected against connecting of inverted-polarity power plug or against connecting of too-high DC voltage (above 15 V) by a fuse. If such event happens and the cooling fans on the back side of the camera do not work when the camera is connected to proper power supply, return the camera to the service center for repair.
