Hi phani, is it a total or a partial eclipse?
If any part of the sun is visible, then you will need a filter at ALL times. So for a total eclipse, you need a filter right up to and immediately after totality. For a partial eclipse, or an annular eclipse, you will need the filter on at ALL times.
The definitive source of information on eclipses is Fred Espenak, who publishes some fantastic information including photography tips here:
If it's the one on February 8th, then I'll be able to see it too in New Zealand - weather permitting! But it's not a total, so we'll need to use filters throughout.
Here's a guide I wrote a while back for total eclipses which might be useful. It includes details of filter material you can buy in the UK - see if there's a local supplier for you...
A total solar eclipse is one of nature’s most secular sights, and with the right technique it’s possible to come home with some truly memorable images.
If you’d like a photo where the Sun fills a large proportion of the frame, you’ll need a powerful telephoto lens. For typical DSLRs with APS-sized sensors, an 800mm lens will produce a solar disk measuring almost exactly half the height of the frame; this can easily be achieved using a 400mm lens and a 2x converter. This is perfect for capturing most phases of an eclipse including the coronal atmosphere. For extended atmosphere shots, 500 to 600mm focal lengths (such as a 400mm with a 1.4x converter) are more appropriate for DSLRs.
To protect your eyes and equipment from the Sun before and after totality you will need a suitable solar filter. Dedicated glass solar filters which screw onto the end of lenses and telescopes are available, but equally good results can be had by making your own using a special sheet of material.
Baader’s Astro Solar Filter Material reduces solar intensity by 99.999% and is ideal for the job – some companies sell pre-made filters using this or similar material - for example at http://www.telescopesplus.co.uk/viewsub ... Filters/21
You should also use a tripod to aim the camera and keep it steady, although at long focal lengths you will actually see the Sun move steadily across the frame as the Earth rotates. The solution is of course to keep readjusting the tripod, but a smooth video head is essential to avoid jerking and losing the target altogether.
As for exposures, study the invaluable table under the photographic section of NASA’s eclipse web pages – see snippet. If you use a 400mm f5.6 lens with a 2x converter, it will have an effective aperture of f11. If your camera is set to 200 ISO you’ll then be looking at a shutter speed of around 1/500 for the whole disc or partial phases with the solar filter attached.
During totality you should remove the filter and use a range of exposures from 1/2000 to 1 second to capture varying degrees of the coronal atmosphere; one of the easiest approaches is to simply take one shot after another at steadily decreasing shutter speeds, repositioning the tripod every few seconds to keep the disc in the middle of the frame. Once totality is over, quickly replace the filter.
Ultimately though don’t become obsessed with your camera, and always leave time to view this magical sight with your own eyes.