Some Notes on Video Camera Astronomy and use of the Phil Dyer Colour Camera Introduction I always wanted to look through a telescope and see those wonderful images of planets, spiral galaxies, nebulae etc etc didn t we all? It doesn t happen, of course. The main problem from light polluted skies is contrast. Increasing aperture (I am now up to 12!) doesn t help much as it makes everything brighter and does not improve contrast. You can take long exposure photos, and I really admire the people that have the technology, patience and determination to integrate hours of exposure to produce the brilliant images that we can all see. Unfortunately, I do not possess any of the above mentioned traits I am much more down the instant gratification end of the spectrum. I have toyed with various things such as image enhancers etc, without a lot of success. Then I discovered the PD Colour Video Camera! Read on - - - The PD Colour Camera This is what Phil Dyer says about the camera. I have no connection at all with Mr. Dyer, but as far as I can tell, it is all true! PD cameras are the latest generation Huviron CCTV cameras, selected for their supreme sensitivity, and modified by us for astronomy uses. The PD video camera is so wonderfully versatile, that you will quickly find it indispensable for most of your astronomy activities. First of all, it s so easy to use. You don t always need to connect it to a telescope. You can use it with small lenses, camera lenses and the like, on small photo tripods. Very light, very transportable. Easy to set up (plugs to any TV). It s powerful. It packs a lot of power into its small size. Whatever lens system you use it with, will seem 4 times bigger so your 50mm camera lens will match any 200mm scope in magnitudes. And even the small lens supplied will show wide views and all those stars you miss out on due to light pollution. It s flexible. It has the sensitivity to display deep sky objects in real time, but also the speed and flexibility to display brighter objects like the moon and planets, and even fast moving objects like meteors and man made satellites. It s adaptable. You don t need to connect the camera to a PC/Laptop, but you can if you like. All cabling, software, etc is provided. Then you can process your observations and dramatically increasing the sensitivity and sharpness of images. It s shareable. You can easily share with others. A whole crowd can view on PC or TV screen even indoors with the telescope outside. No more standing around in the cold waiting for a short turn at the eyepiece. All this might sound quite complicated but its simple really, and these specially written instructions are designed to have you up and running within a few minutes.
The PD Camera package (Full Kit): PD Colour Camera Wide-angle lens 12V mains adapter Cable and connectors for TV/PC display Capture device for PC Display and Capture 1.25 Eyepiece Adapter for telescopes When in operation to take stills as a screen grab the camera takes a series of exposures at 1/50 th second, and will internally stack and process up to 1024 of these 1/50 th second frames. This takes around 20 seconds. This means that your mount only has to track well (if at all) for 20 seconds. You can then take as many of these 20 second frames as you like and stack them in Registax, or something similar, that then takes care of any residual movement. I usually take around 10, giving a total exposure of 200 seconds or so. You can also use the camera in movie mode, recording the individual frames as an.avi movie. You do this for brighter objects such as the moon or planets, and again use Registax to stack them. In this case you can use faster shutter speeds to keep distortion from atmospheric wobble down. Again, generally, I use around 3000 frames. The Question of Contrast Once we have images in electronic form, all sorts of image processing options are available. As far as deep sky imaging is concerned, one of the most significant options is to improve the contrast of the images, usually non-linearly, by using a gamma function or similar. I use GIMP 2 to process my images and in that software it is badged curves. This is all explained in my associated document Imaging Deep Sky Objects with the Phil Dyer Colour Video Camera. You can also sharpen images with dramatic effect on planetary images. It is important to note that none of these processes adds anything to the image that was not there originally, they simply emphasise or suppress features.
Some examples of what you can do. Here is a selection of deep sky images that I have acquired with my set-up
Here are a few images of Jupiter acquired with the camera in movie mode:
The Window-Sill Through Double Glazing (WSTDG) Observatory Once you have realized that you can electronically enhance image contrast, some unconventional approaches open up. I suffer from a neurological problem that often prevents me sleeping. One of the best palliatives is distraction, and what better distraction could there be than the night sky? However, it takes some determination to get up and get dressed in the early hours, so I tried an alternative strategy. Our house faces south-ish over a large garden. So, mounting a small telescope on the window-sill of the spare bedroom enables observation in comfort at all times of the night. You have to look through the glass though, as if you looked through an open window, the air currents would ruin the seeing. The first go was with a 76mm reflector seen below with the camera attached. Here are a couple of images of the moon and the Orion Nebula with this set-up.
Things have now moved on. The next image is using a 4 refractor through the double glazing, but not on the window-sill. The latest WSTDG instrument is an 80mm f/5 refractor with an equatorial drive which does fit on the window-sill, and that is where the final image comes from. So, in conclusion, the PD camera is a great low-cost bit of kit enabling all sorts of imaging to be done very easily and quickly. Not professional quality, but huge fun! Roger Samworth 16/04/2015