The detailed pictures of the event were taken on a Minolta 7000i SLR 35mm camera fitted with a 600mm mirror lens plus x2 doubler. This combination gave a field of view of about 1 degree by 1.5 degrees, thus making the sun actually quite hard to find! For the shots of the partial phase, a mylar filter (made from one lens of a pair of eclipse-viewing spectacles!) was inserted into the mirror lens' filter mount at the focal point position, thus avoiding the need for a large filter over the front of the lens but running some danger of affecting the internals of the lens by heat (still seems OK though). The ensemble was mounted on a standard photographic tripod, weighted for stability, and counter-balanced (with a thermos flask of water on a piece of string!!) to help avoid excess movement when the tripod's elevation clamp was tightened.
The basic lens claims to be f8, but actually acts as f11, and so with the +2 stops imposed by the doubler the combination was effectively working at f22. Research indicated that, with 400ASA film, exposure times of around 1/1000sec for Bailey's Beads to 1/125 for prominences to large fractions of a second for the corona would be indicated. Accordingly, I started to take at 1/1000sec and then worked up the entire exposure range to 2sec, in a sequence of twelve shots (using a remote-control to avoid camera shake), in order to capture everything. I then allowed myself the luxury of viewing the eclipse "naked eye" for a while (it's easy to forget to do this!) before working down the sequence again. I was then taken slightly unawares by the appearance of the chromosphere just before the end of totality so rather under-exposed it at 1/1000sec. However, this was correct for the beginning of the Diamond Ring, the last (rather bright!) shot being taken at 1/2000sec.
The first sequence was taken with the sun highly off-centre in the frame, in order to maximise the chance of capturing detail in the far outer corona. In fact, this didn't seem to catch anything extra but did allow a star (1-Geminorum) to sneak in! The second sequence had the sun more nearly centred, to ensure it didn't slip out of the frame during the exposure run. The camera was also rotated on its axis (using a facility on the mirror lens mounting) so that the sun would track down the wide axis of the viewfinder as it moved across the sky, thus avoiding the need to frequently adjust the tripod (rather sensitive!).
Due to the camera rotation, the images are not "as seen on the day" but rather are rotated by about 90degrees clockwise - the moon actually started to encroach on the sun at about the 7o'clock position. This rotation does however have the extra advantage that the long axis of the images is now the same as that of computer monitors!
The pictures were taken on slide film (as we give slide shows to interested groups) so had to be scanned before image processing could begin. This was done by use of a slide-convertor on a standard flat-bed scanner, using a resolution of 1200dpi (resulting in raw images of over 5Mbytes each in size!). The images were then centred, and cut down to a standard size of 1280x960 pixels for archiving. Views for the web-site and the animation were made from these masters by cropping and re-sizing, then saving in JPEG format for the pictures and GIF for the animation. The composite of the corona was constructed from eight shots whose different exposures brought out different parts of the image. "Cut & paste" techniques did not work at all well, so I used a morphing program to combine 50% of each of pairs of images, then combined the four resultant images into two and then finally merged these into the final result.
And if the above sounds straightforward - it wasn't!! Firstly, the filter cut down the light so much that focussing was quite difficult as the image brightness was so low. I think it's fair to say that the sharpness actually achieved was "there or there abouts" but a pedant might refer to it as "a little soft"! Then, the small field of view and somewhat delicate tripod adjustment meant that, with the eclipse starting at 9mins past 3pm, at 8mins past I had not even managed to get the sun in the viewfinder! Thankfully it wandered in just in time, but I certainly held my breath when re-adjusting to take the second photo sequence. Finally, assorted technical difficulties made the image processing a bit of a task (not helped by my ageing computer, some would say!) but we got there eventually - I hope the end result has been worth it.
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