4. Flash notes

A.     Existing light photography is ideal. The goal of flash photography is generally to balance the flash with the ambient light.

1.      Try adding light before using a flash.

B.     Using flash

1.      Needs

i)        Fill flash- Using flash to boost daytime portraits. Shadows underneath eye sockets, etc.

ii)      Color balance - to balance fluorescent, daylight film indoors, churches with TV lighting, etc. Flash is balanced with the sun

iii)    Light the entire scene- add all the light you can

iv)    Rear curtain sync- flash added at the end of a long exposure

v)      High speed- stopping high speed action with special triggers

vi)    Multiple flash- multiple burst of light in one exposure

vii)  Multiple flashes- more than one flash (ie piece of equipment)

viii)            Portrait lighting- studio lights, flood lamps, reflectors

2.      Challenges

i)        Shadows

(1)   Move subject further from the background

(2)   Move flash off camera so it can stay above the center of lens, but raise up

ii)      One dimensional

(1)   Get your subjects at the same plane of light

(2)   Bounce light

(3)   Reflect light into the scene

iii)    Red eye

(1)   Get flash away from the lens

(2)   Increase ambient lighting

iv)    Limited distance

(1)   Increase ISO (film speed) which increases sensitivity of film and increase the distance light will effectively travel.

        - Note - ISO affects the flash effective distance. The flash doesn’t get all of a sudden more powerful, the flash is more effective. IOW, the film, or sensor is more sensitive.

(2)   Use a stronger flash

(3)   Get closer to your subject

3.      Types of flash strobes (Based on the type of exposure mode.)

i)        Manual - everything is dumped from the flashes capacitor every time you press the button. So, the maximum power of the flash has to be known, and you set the exposure based on the distance of the subject from the flash. With Digital, this is pretty easy to do trial and error, but there is a mathematical way to calculate the flashes Guide Number and the subject distance to F/stop setting.

ii)      Auto - the flash determines the exposure based on the built in Thrystor. This is a little eye on the front of the flash that read the light that bounces off of the scene. This happens at the speed of light. You press the shutter button, the flash fires, hits the subjects, bounces into the Thrystor eye, and shuts off the flash and then the shutter closes. This can be pretty accurate, sometimes even better than modern iTTL systems as it sometimes does a better job of a bright or dark object in the view finder when it is not the main scene.

iii)    TTL - TTL means that the CAMERA determines the exposure by reading the light that bounces off of the subject after it has been flashed. This all happens at the speed of light with the camera telling the flash when it has enough light and to shut off.

4.      Settings - every flash is different, but using the school's Vivitar 283, which is a an Auto/Manual flash. Most modern brand name flashes will have TTL AND Auto and manual. If you buy a cheap generic flash, it will probably only be Manual...or maybe Auto

i) Vivitar 283 Flash Distance Ranges: Yellow 5-43, Red: 4-30’, Blue: 2-15’, Purple: 2-11’

ii) Once you know the subject distance, you look at the side of the flash with the built in calculator. This calculator does not do ANYTHING to the flash output...it's only purpose is for setting the f/stop on the flash to match the flash. Basically, the flash is going to control it's output on it's own. So, using the calculator, if you are on ISO 400, and your subject is 10 ft away, if you put your flash on the Red setting, you would put the F/stop on 5.6.


Some common questions regarding flash:






Controlling Flash - simulator at Photonhead.com

Lighting - My own presentation regarding the treatment of lighting