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Basic Astro Photography
Left to right: Comet Hyakutake, the 'tail' of Scorpio, the Souther Cross, both over Sri Lanka Click on any of the above pictures for an enlarged view - return by right clicking the mouse What do we mean by 'Basic Astro Photography'? The idea is to take an ordinary camera, usually a 35mm single lens reflex type, mount it on a tripod, point the lens at a picturesque area of sky and simply take a picture. The pictures shown above are all taken by my colleague Graham Bate and show that with a little patience and a suitable foreground, many basic cameras can be used to produce pictures that are quite capable of being enlarged to 16 inches by 20 inches or more. These pictures have been deliberately reduced in resolution by scanning at 200 dpi and reduced in size to both limit their use by anyone copying them and to reduce their file size to suit the internet. The originals print quite well at poster size! The choice of both lens and film type is limited by the need to reduce star trailing caused by the earth's rotation, basically the idea is to choose a fast wide angle lens and fast film. The shots above are taken with a Pentax 50mm f1.4 lens at full aperture, the film was Kodak Ektar 1000, exposure around 20 to 30 seconds. For slides try the brilliant Kodak Ektachrome P1600X, note it's only sold in packs of 5 here in the UK. Most lenses produce unwanted effects when used at full aperture, this shows itself as triangular shaped star images towards the edge of the field of view. Another effect is the tendency for the edges of the image to be darker than the centre, this isn't such a problem with a really dark site - most of us aren't that fortunate. The answer to both of these defects is to stop the lens down, however, then you cannot image many stars at these apertures in the few seconds exposure that minimises star trails! The only solution is to use the best lens you can find - even that isn't likely to be as perfect as you will probably expect it to be. The next step up from basic astro photography is to mount the camera 'piggy back' on an ordinary equatorial mounted telescope, see 'Piggy Back Photography'.
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