i have made up this table showing equivalent exposures for taking photos like star trails etc,
feel free to save it and print it out (looks best on A4 size paper)
its really simple to use, use your camera's meter to work out correct exposure, look for the line where shutter speed and aperture meet, then follow the line in or out for the same exposure with either a faster or slower shutter speed and a larger or smaller aperture.
most of you are experienced enought to work these out by yourself, this just makes it alot quicker and easier
each black line is a full stop, each red dot is 1/3 of a stop.
for exposure times over 30 seconds the time is there for each 1/3 stop increment (you will need to set this time on a countdown timer, as most canons stop at 30 seconds)
table can be found here
http://i103.photobucket.com/albums/m150/Echo63/IMG.jpg![]()
i have not imbedded an image of the table as it would be too small to read or too large and be a problem for 56k users

