A modification to the Hague camera mount is described that has proved itself with a standard lens and short exposures with very fast films.

Photographs of the night sky can be very successful with a standard lens of approximately 50mm, using a fast film and exposures of no more than 20 seconds to prevent trailing of the stars. However just by increasing the exposure time to one, or even better 2 minutes, together with very fast 1600 ISO slide film dramatic results can be produced, from a dark site.

During the recent apparition of comet HaIe-Bopp I was able to take some photographs from Central Wales where there was very little light pollution. Using a simple driven camera mount, a 45mm f2 lens together with Fujichrome 1 600 and a 2 minute exposure produced some spectacular slides. When enlarged the prints showed excellent grain structure even up to 8 x 10 inches.

A forthcoming trip to Australia to visit relatives during july and August meant that I needed some means of taking photographs of the night sky with exposures up to 2 minutes, and since I was travelling in south Australia and Queensland I needed a driven camera mount that could also be used in varying latitudes, one that would pack easily, weigh little, and cost next to nothing. The only possibility appeared to be the Haig Mount, named after George Haig who first described it. This is also known as the Scotch mount, perhaps more correctly as Scottish mount, as it is not Whisky driven, the hinge mount or the Screw Drive.

The Hague mount characteristically consists of a large block of wood about 3OOmmx 80mm x 100mm sawn at one end to the observers latitude. Fixed to the angled end is a short plank 3OOmm x 150mm x l2mm and hinged at one end is an identical plank, 291 mm from the hinge end in the fixed plank is an undersize hole through which a 1/4" Whitworth bolt is screwed. This bolt acts on the second plank such that one turn of the screw per minute will advance this part at the sidereal rate. A ball and socket camera mount is attached to the moving board so that the camera can point at any part of the sky. While working excellently the disadvantages of this arrangement for my purpose, is the overall size and weight, and because of this cannot be used on a standard camera tripod. Apart from size there is a further problem caused by the screw passing through an undersize hole, in the bare wood, tending to make the action rather jerky.

Firstly I thought these problems could be solved by using a captive bolt instead of the undersize hole, although in practice two bolts were needed one on each side to keep the bolt moving in a straight line. Secondly two narrow pieces of wood were used in place of the two short planks, and thirdly the large block of wood was dispensed with altogether to be replaced by the tripod head itself. Since the exposures were intended to be short, the tripod head could be tilted to the appropriate latitude with a detachable sighting rod adequate for alignment on the pole.Furthermore by reversing the tripod head the mount could be used either in the northern or southern hemispheres. One further modification was made, which in the diagram is referred to as a strengthening bracket, and this was needed to prevent sideways movement of the moving piece of wood relative to the fixed piece, although it could still allow exposures up to five minutes. Haig recommended that the bolt be turned in time with the second hand of a watch, but I preferred to count the seconds, moving the bolt after each five second interval, as I considered a five or ten seconds error in two minutes to be insignificant, and this proved to be the case.

The camera mount was a total success and provided a record of the southern Milky Way beyond what was possible using a 20 second exposures, with a fixed camera, and much fainter than naked eye visibility. Prints from the slides could be joined together to make a strip of the entire southern Milky Way. A4 photocopies could similarly be joined to make a poster more than a metre in length.

Since returning to Britain I continued the project by photographing the northern Milky Way from North Wales. Despite a high wind this too was successful with excption that there was considerable sky glow presumably from the industrial midlands. I am sure the mount could be further modified to include a small telescope to make polar alignment more accurate, thereby allowing exposures of more than two minutes, although in this country there are few site where this would be possible.