I have canon sx40, I am using it for three years, from last month in the start time always it comes set time and if I skips then taken images takes 1980 as date, I can not understand what is the problem, is there any internal battery in camera, do I need to change it ?
The SX40 uses a rechargeable built-in date/time battery. They are supposed to keep working for about 7 years, but it appears yours has died a little early.
It is not user replaceable.
You will need to continue setting the date each time you remove the main battery, or you could have Canon replace the date/time battery.