Flash Unit No. 1 - Theory Notes

Flash Unit No. 1 - Theory Notes

Fill-in-Flash

A fill in flash can really help a picture get nicer. Without a fill in flash the subjects in the picture might get some very hard shadows or can be overly backlit so the faces are underexposed which ruins the picture. A fill in flash can also make a picture look much nicer by highlighting the eyes of the subject or adding another nice effect.

The photographer of these pictures used different settings with the flash. In the picture to the right there was no flash used and the sun gave the light. The picture to the right used a flash and it highlighted the details on the clothes and there is a clear different between the two pictures.

A fill in flash can highlight the subjects and add effects to make the pictures much nicer. A fill in flash is meant to reduce the hard shadows and balance out the light on the subject.

Built-In-Flash

Most digital cameras today have a built in flash.

Today, most digital cameras have a built in flash. The built in flash works for indoors and outdoors. Using it outside can help the picture by softening the eye shadow and the shadow under the chin. A common problem that is created by built in flashes are that often red eyes come when you have taken a photo. Red eyes appear if the flash is too close to the camera lens.

The red eye is caused from reflection from the color of the eye blood vessels in the retina.

Even though a flash is not required, it is often used and can create another nice effect to the picture. In the picture to the right a flash is used and the wheat stands out.

Flash Guide Numbers

The guide number for an electronic flash helps quantifying its maximum output in terms that a photographer can relate to - aperture and distance. Putting the aperture and and distance (from flash to subject) will give the guide number and the combination will result in enough light for proper exposure.

The three most common ways to use the guide number are:

1)Find the correct aperture for a subject at a given distance when using manual flash

2) Find the maximum distance a flash will properly illuminate the subject at the given aperture

3) Comparing the relative power of the different flash units (higher guide number = more power)