Steve Massey's Astronomy Page HOMEDeepSky Pictures
An Introduction
Applications

Extreme Video

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Processing Images

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Video Astronomy is perhaps the easiest and most affordable method of solar, lunar and planetary imaging around today. In fact, several new cameras available today have onboard image integration capabilities and are so highly sensitive they are being used to image deep sky subjects without the aid of a military grade image intensifier like we used to use. Advances in CCD and CMOS technologies and software along with market demand has substantially reduced manufacturer costs thus making this wonderfully simple recording medium more readily available to the average consumer.
The heart of modern video cameras is its image sensor mounted on a small printed circuit board which also contains all the processing circuitry to make it a complete video camera device. Low-cost off-the-shelf C-mount cameras are also available in convenient pre-fabricated enclosures. Most are based on automatic circuits offering little user controllability however some do offer adjustable functionality via software. sat24s.jpg (10415 bytes)
Saturn was captured using a surveillance based B&W video camera (see below) and coloured filters.
These days there are a number of commercially available systems designed specifically for use at the telescope. The GSTAR-EX2 is one such camera that provides complete user control flexibility for doing both deep-sky and planetary imaging with live on-screen display. Depending on the image sensor used and how well the camera electronics employed do the digital conversion, compact video technology today can produce astounding high resolution images. The images in these pages are purely an example of what can be achieved.

Click Here to see a list of video animations

Below: Jupiter and Saturn in February and March 2005 - 254mm (10-inch) Newtonian RGB filters and a common black and white security video camera. Processed with Registax and Photoshop.

 

  Jupiter & Saturn 2005
 
Applications:

Conventional video cameras are short exposure devices and as such have (until recently) been best suited for imaging the brightest celestial subjects like the Sun, Moon, planets and meteors etc. When using common low light security cameras without onboard frame integration and special software, faint fuzzy objects such as nebula and galaxies reveal little detail unless the camera is coupled to an image intensifier as mentioned earlier. But these standard cameras can reveal more than is visible on a noisy monitor by applying software such as  (AstroVideo) by COAA. This software essentially sums hundreds or even thousands of individual video images producing a highly improved signal to noise image and revealing extended structure that appears to be invisible when viewing the monitor in real-time.  Deimos in June 2001 captured using AstroVideo..  

mars.jpg (20887 bytes)
Mars captured using an old Astrovid 2000 video camera at f/36 on a 24-inch Cassegrain with colour filters. Note the less than natural pinkish appearance is is due to the fact no IR blocking filter was used.

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Extreme Video Astronomy

Until early 2000's common low light security cameras were only suitable for imaging the brighter celestial targets. Faint deep-sky targets required the use of expensive image intensifiers like those used by the military. Prior to the new millennium, obtaining images with inexpensive video from light polluted suburban sites like the M83 image at right was nothing short of fantasy. In a few short years however, several amateurs began experimenting quite successfully with modified (cooled) webcams combined with image stacking software to longer exposure video based results. I like to refer to this type of astro-videography as 'extreme video astronomy' since the technology is now so advanced and the results quite remarkable.  


M83 in Hydra - GSTAR-EX2 camera 12-inch scope

 
The new range a of highly sensitive Sony image sensors (CCD's) have made this all possible. Similar CCD's are also now being produced by other semi-conductor manufacturers including Panasonic.

 

The GSTAR-EX cameras use highly sensitive, low light image sensors manufactured by Sony.

The standard GSTAR-EX camera facilitates on board frame integration from x2, x4, x8, x12, x16, x24, x36, x64, x96, x128. In x 128 mode the screen is refreshed once every 2.6 seconds. The camera also features on screen display with several other functions including signal gain and shutter speed controls.

Newer models are the GSTAR-EX3 and GSTAR-EX4 high resolution, full colour USB3 based cameras. See what can be done with these here.

 

NGC 6872 (300 stacked video frames)

The results are amazing! Even during normal video operation (integration mode switched off) I could see nebulosity about the trapezium stars in the Orion nebula. A far more expensive camera was the compact Watec 120N. For some time it claimed to be the most sensitive video camera available to amateur astronomers today offering long exposure times up to 10.24 seconds but was unfortunately riddled with hot pixels. Another camera, the excellent GSTAR-EX2, was capable of up to 5.12 seconds frame accumulation time but without displaying overly obvious pixels due to its smart internally managed noise / dark frame subtraction and cancellation technology. It works more effectively with non guided mounts at producing deep, detailed images with nice round stars.
 
This was taken from suburban Sydney while the light from a gibbous Moon was scattered through thin haze in the atmosphere. Under such conditions I certainly wasn't expecting to see such results.

Taken at prime focus with a 250mm f/5 Newtonian, these images were acquired using the 128X frame accumulation mode of the GSTAR-EX camera with True Technology RGB filters. A dark frame of the same exposure setting has been subtracted to remove hot pixels. But things have come along way since the introduction of these cameras although the GSTAR-EX and EX2 are still quite widely used at the time of updating this piece.

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Integrated video image of M104

 

GSTAR-EX Deep Sky & Planetary CCD Camera

Recording images:

This can be achieved in two ways: Directly to video tape (Digital (DV), Beta or SVHS quality is recommended) or via a computer fitted with a video frame capture device. A modified webcam can also be used to create wonderful images and with the convenience of plug-and-play USB port connection.

Advantages of Video for Astronomical Imaging:

During moments of poor seeing (most apparent when using higher powers), single snap shot pictures can be blurred or distorted due to local and high atmospheric air turbulence.

Talking about telescopes and video astronomy (YouTube Audio)

 

Capturing objects as a stream of pictures with a computer in media file AVI movie format (or similar) or to videotape allows the user to replay the sequence frame by frame until the image presenting the least distortion appears. This frame can then be stored as a single image using image capture software. Aside from the technical benefits, video is an extremely cost effective imaging medium within the budgetary reach of most amateur astronomers.

 

 
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Processing Images:

For digital imagers, the computer has become as much an essential tool as the telescope itself. With raw (single) video images, video noise (a speckled appearance) is apparent in each still frame captured. This is particularly the case with images captured from paused videotape. Software tools such as Adobe PhotoShop, Ulead's Photo Editor or PaintShop Pro are excellent commonly available programs for processing images. These programs enable the user to stack several of the best images in order to reduce the background (thermal) noise with layering tools and also offer several other processing filters for improving feature contrast.

Capturing Video to the PC

For many years I used my own software AstroAVI which records all my equipment and site information along with dates and times and the target object details in a convenient database for later reference while digitising images from video or directly from a camera. I later developed the program as GSTAR4 Capture which is now primarily edited by friend Chris Wakeman and the program has evolved greatly over the years.

Image Selection Software

Eyeballing the sharpest images in a planetary or lunar video movie is still sometimes the most efficient method for best results. For selecting the best captured video frames I use VirtualDub or GSTAR Capture's AVI Toolkit. I then import the exported bitmap images one of the programs listed below. 

Stacking Images and Dark Frame Subtraction

A couple of automated image stacking tools I use and highly recommend are:

Registax (Highly Recommended)
DeepSky Stacker (Highly Recommended)
AutoStakkert (Excellent)

If you want to try creating colour images with a black and white video camera then you'll need to use Red, Green and Blue light filters such as the RGB Dichroic filter set from True Technology. Using one of the aforementioned software packages, you can then apply the resulting monochrome image from each corresponding filter to the appropriate colour channel of an RGB 24 bit image to create a colour picture.

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Deep Sky Video Astronomy

An in depth guide to the wonderful world of modern video CCD technology and how it is used to image faint deep sky targets with basic telescopes from the backyard. Plus in-depth image processing procedures and steps to getting the very best out
of your video and images.

Steve Massey & Steve Quirk

Soft Cover

 

Deep-Sky Video Astronomy

 

 VIDEO ASTRONOMY - Steve Massey Astronomy