Taking a photo of the Sun needs to de done in such a way that ones eyes and the camera are not permanently damaged by even a very short exposure to the intense light. Never look or point a camera directly at the Sun without the correct type of solar filter in place.
What is needed is a filter which is designed for the job. There are many to be found on the internet with a vast range of prices. The cheapest use a specially made thin film which cuts down the light something like 10000 times. One such is the Orion Safety Film Solar Filter sold on Amazon by Orion Telescopes. I ordered one expecting it to take a couple of weeks to arrive from America and was pleasantly surprised when it arrived in a few days from a European base.
It is designed to fit a particular telescope but I had an idea it could be adapted to fit on the front of the 70D with 100-400mm zoom lens. The filter body is made of cardboard which helps to keep the price down. With it came a length of self adhesive foam which I stuck inside the frame - not a tight fit yet so I will find some foam draught excluder strip to put another layer in it. For safety the filter needs to be a tight fit so there is no chance of it being blown or knocked off while in use.
I fitted it temporarily to get a few trial hand held shots:
|Canon 70D 400mm 1/250 sec f5.6 ISO 800|
I am quite happy with the result as seen in this cropped photo which shows up Sun spots nicely. Not bad for a £25 filter! One reason I chose this filter was it displays the Sun in an orange - red colour. Some of the cheaper film filters give a b/w result. It depends on what wavelength of light the filter is designed to allow through.