54°12.0' N; 4°25' W

                      Video Astrophotography

                    An Increasingly Popular Form of Astro Imaging

Video astrophotography is an increasingly used method for imaging celestial objects. The camera I use is the GSTAR-EX integrating astronomical CCD video camera. The GSTAR-EX is an image intensifier and is extremely light sensitive. It can internally stack frames up to every 2.56 seconds using its internal memory. These frames are then output to a capture device such as a TV, monitor, laptop, video camera, video recorder, DVD recorder or MP4 recorder. The capture device saves the outputted frames as an animated film usually stored in AVI, ASF or WMV format. This film is then processed to produce a high resolution photograph.

There are a few reasons why I prefer this method of astrophotography. Firstly, polar alignment does not need to be highly accurate as it does for non video capture (CCD, DSLR, SLR photography). Video astrophotography is much more forgiving not even needing a guidescope or guiding device (such as an SBIG ST4). Secondly, you can enjoy watching live video of the celestial object while it is being captured. Thirdly, at the end of the process you will have a video and photograph of the celestial object.

On brighter objects I tend to capture 30 minutes of video but on dimmer and more distant objects I capture one hour of video. This provides enough quality frames to align, stack and process a high quality image. Various software is required at different stages of the workflow to help produce a photograph from the original captured video. The software workflow I use is as follows:-

•  ULEAD VideoStudio 7 - This is used to stream the captured video to uncompressed, unprocessed raw AVI format.

•  AVERY LEE VirtualDub 1.7.5  - This is used to strip out audio data, decimate frames by the appropriate frame rate and output in AVI format.

•  COR BERREVOETS Registax 4.0.1.0 - This is used to align, stack and process each frame stored within the AVI file, output in BMP format.

•  ADOBE Photoshop Elements 5.0 - This is used to process & enhance the maximum detail within the image, output in TIFF & JPG format.

•  NEAT IMAGE Neat Image 5.8.0 Demo - This is used to remove unwanted noise and smooth the final image.

   Screen shot of a raw 2.56 second integrated frame       The aligned, stacked image from Registax      The final processed image from Photoshop

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                                                           Summary of Advantages and Disadvantages of Video Astronomy

Advantages                                                                                                   Disadvantages

Less accurate polar alignment required                                                      Small microchip (7.40mm x 5.95mm) not suited to widefield imaging

End result is a video and a photograph                                                       Lower resolution (768 x 576) than most DSLR's & CCD cameras 

Image intensifier is extremely light sensitive (0.0001 Lux)                         Less detailed images produced (than DSLR or CCD camera)

No guidescope required                                                                                RGB filters & filterwheel required for colour imaging

No guiding device required                                                                           Much more effort in processing a full colour image

30 frames (images) are captured every second

Lightweight more portable setup for photography

Very little photography knowledge required

No adapters (T-Rings) required

Ability to watch video while recording

Small & lightweight camera

Highly sensitive chip that will penetrate deeper space

Easier to obtain the perfect focus point than a DSLR camera

Great for outreach sessions (image relayed to big screen)