Candid photographs are immediate and simple. It means something honest, frank, open, sincere and truthful. It actually means that you are just clicking exactly what you are seeing, not rearranging any composition or using any models. The photographer is with the subject and clicks everything honestly and sincerely.
Even if you are a natural life photographer like I am fill-in flash is a trick to add sparkle in the eyes of the subject, this can be done on bright sunny days, in natural light glamour settings or evenly lit overcast days. The trick is to expose for the general light setting using the shutter speed, for those sexy natural light bedroom settings it was usually about a half a second but for those Sunday afternoon picnics usually at about 125th of a second and then finding the right aperture to gain a correct exposure. Now depending on whether it is bright sunlight or an overcast day that is your problem will determine whether you use the same exposure on the flash or one two or three stops below the correct exposure, if it is a bright sunny day be looking at the same power almighty one stop below to set your flash if it is an overcast day it will be 2 to 3 stops the correct exposure. With some more expensive flash gun you"ll be able to set it to half or even third stops so you will be able to achieve -1 1/3 stops which was my particular favorite however I used to use any way down to -3 stops in evenly lit overcast days or dimm sexy bedroom sceans, but sometimes especially with weddings in the winter at six o"clock it"s night time and I would often find myself with 8 second exposures using a fill-in flash of approximately -1 1/3 to achieve quite secular results, in fact I often heard people whispering behind me saying "none of these are going to turnout" but boy were they wrong and this was in film days when there was no opportunity to check if i had done it right, but for those sexy scenes in the bedroom the trick was not to get a shadow to show on her breast from the open shirt, for a more detailed article on fill-in flash go to