Starlight Xpress SXVR-H16

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Overview

Function Description
Important Technical Specifications
Usage Features
Maintenance Features

The document describes the Starlight Xpress SXVR-H16 CCD camera, a large-format, high-resolution cooled CCD camera specifically designed for astronomical imaging.

Function Description

The SXVR-H16 is primarily used for capturing deep-sky astronomical images, but it can also be adapted for lunar imaging. It features a fast USB2 interface for quick image downloads and includes software for camera control, image processing, and autoguiding. The camera is designed to work with telescopes, and the manual provides guidance on achieving optimal optical matching and focus for astronomical objects.

Important Technical Specifications

CCD Type: Kodak KAI4022 Interline CCD imager.
Pixel Array: 2048(H) x 2048(V) pixels.
Active Area: 15mm x 15mm.
Pixel Size: 7.4 x 7.4µM.
Number of Pixels: 4,096,000.
QE Peak: Approximately 52% at 500nM.
Download Speed: Approximately 2 megapixels per second, allowing a full resolution 16-bit image download in about 2.5 seconds.
Cooling: Cooled CCD camera, with a recommended set point of -10°C for normal use, or colder in winter months. For indoor conditions, a set point no lower than -5°C is recommended due to limited airflow.
Dark Signal: Typically 0.01 e- per second at 10°C body temperature.
Power Consumption: 220V / 110V AC @ 12 watts max., 12V DC @ 750mA.
Interface: USB2.0 (not designed for USB1.1).
Guider Output Port: 6-way RJ11 socket, compatible with standard autoguider inputs of most telescope mounts. Provides 4 active-low opto-isolator outputs and a common return line, capable of sinking a minimum of 5mA per output.
Serial Ports: Two fast serial ports (5-pin 18-way connector) for external accessories, configurable as a serial port divider box.
Operating System Compatibility: Windows XP or Windows Vista.
PC Requirements: At least one USB2.0 port, 500MB RAM, graphics card capable of 1600 x 1200 pixels and 32-bit color. Medium specification Pentium (1GHz to 3GHz) processor is ideal.

Usage Features

Quick Start and Setup: The manual provides a 'Quick Start' section to get the camera operational quickly. This includes:

Package Contents: SXVR-H16 camera head, power supply module and cable, 3-meter USB2 camera cable, 2" drawtube/M42 'Pentax' thread lens adaptor, ST4-style mount guider cable, and a software/manual CD.
USB System Installation: Instructions for plugging in the USB cable, running the software installer from the CD, and connecting the camera. It also details how to confirm successful driver installation via Windows Device Manager.
Camera Control Defaults: Guidance on setting up initial camera control defaults such as background image area, FITS format, star mask size, and telescope guiding output.

Imaging Features:

Focusing: The SXV_H16 software includes a focus routine that repeatedly downloads and displays a 100x100 pixel segment of the image at high speed. Users can select a star, adjust contrast, and fine-tune telescope focus to maximize the 'peak value' (brightness of the brightest pixel).
Exposure Control: Adjustable exposure times, continuous mode, and options for averaging multiple exposures.
Image Saving: Auto-save image functionality with sequential file naming in FITS format.
Dark Frame Subtraction: The camera generates relatively little dark signal, but recording dark frames for each exposure time is recommended, especially for longer exposures. The 'Merge' option in the software allows subtraction of matched dark frames.
Flat Fielding: While less critical than dark frames, flat fields compensate for uneven illumination and CCD sensitivity. The manual describes a method using twilight sky and a diffuser.
Image Processing:
- Contrast Stretch: 'Normal Contrast Stretch' allows adjustment of black and white limits on the image histogram to enhance brightness and 'crispness'.
- Filtering: 'High Pass Low Power' filter for moderate image sharpness improvement. A 3x3 'Median' filter can remove isolated hot pixels by replacing them with the median value of adjacent pixels.
- Image Stacking/Summing: The 'Merge' menu allows summing or averaging multiple images to improve the signal-to-noise ratio.
- 'Slew & Sum' Imaging: An automatic image-stacking mode where the camera takes sequential exposures, which are then automatically aligned and summed. This helps overcome poor RA drive errors.
Astronomical Imaging Guidance:
- Optical Matching: Emphasizes the importance of matching the H16 to the telescope, recommending wide-field refractors or flat-field reflectors. Suggests an image scale of about 2 arc seconds per pixel for deep-sky images and provides a formula for calculating optimum focal length.
- IR Blocking Filters: Recommended for use with camera lenses to reduce 'soft focus' caused by the SXVR-H16's strong infrared response.
- Lunar Imaging: Suitable for impressive whole-moon pictures, requiring very short exposures (around 0.5 seconds) and potentially ND filters or aperture stops to prevent saturation and smearing. Aggressive sharpening filters like 'Unsharp Mask' can be used effectively.
Autoguiding:
- The SXVR-H16 can be used as an autoguider with an optional add-on autoguider camera head.
- The software provides an autoguider control panel for selecting a guide star, adjusting guiding rates, and training the system to determine the angle of the guide camera relative to the RA and Dec axes.
- Manual 'Move Telescope' buttons allow testing guiding control.
- Troubleshooting guidance for non-circular stars (adjust guiding parameters, investigate mount rigidity/drive performance) and persistent drift (check N/S and E/W directions).
- Suggests adding a small weight to the declination axis to prevent 'bouncing' in the gear teeth.

Maintenance Features

Routine Maintenance:

Dust Removal:
- Dust on the optical window (outside surface) can be removed with a lens cleaning cloth or 'air duster'.
- Dust on the CCD faceplate requires dismantling the camera. The procedure involves removing the camera back plate, unplugging the fan lead, lifting the PCB, and then carefully cleaning the CCD faceplate with a good quality lens cloth (e.g., Micro-Fibre type) and high-grade isopropyl alcohol. Reassembly is in reverse order.
Condensation Prevention:
- The camera is designed to minimize condensation by limiting air volume in the CCD cavity.
- If condensation occurs, store the camera in a warm, dry place or in a plastic lunch box with a sachet of silica gel desiccant.
- Important Warning: Do NOT leave the camera switched on for long periods between uses, as the cold CCD can collect ice, which can become corrosive water on the cooler and CCD pins when power is removed. If significant moisture is present, dismantle and dry the camera thoroughly.

Alignment:

CCD to Optical Axis Alignment: The large CCD area can lead to alignment problems between the CCD plane and the telescope's focal plane. The front plate of the SXVR-H16 has three sets of antagonistic screws that allow tilting by up to +/- 1 degree to adjust alignment. Users are advised to slacken the appropriate set screw, turn the adjacent cap head screw, and then re-tighten. Avoid raising the plate more than necessary to prevent light leaks.

Warranty and Support:

The equipment is covered by a 12-month guarantee for faulty design, material, or workmanship.
Users are advised to consult the fault-finding information and contact Starlight Xpress for further advice if problems persist. A message board service is also available on their website.