Using

Creative control of flash Off flash

Using flash

• Built in flash on most are not very good for anything than the occasional snapshot of family and friends. • They are very low power, their close proximity to the lens axis leads to ‘re-eye’ and they give that “Rabbit caught in the headlights” look. • If you are serious about your then you should consider getting a separate flash gun to give you more control

Separate flash • There are different types of flash that you can buy • There are dedicated guns made by your camera manufacturer – which may have lots of bells & whistles for very creative work • There are independent makes that will serve well and may be sufficient for your needs. • This one is a cheap independent one for Canon & Nikon at £28 from Amazon • Basic guns are usually fairly cheaply made and will not have a full function set Other independent guns • Other flashguns will have more power and capabilities. o This one has variable power, zoom, bounce capabilities, Multi-flash setup and remote control to rival some of the camera manufacturers guns. o This one is the Yongnuo YN-560 and is available for £56. o These have quite a good reputation but I have not used one • The flash guns shown, and most manufactures own brand ones have several advantages. o The head can be tilted up and swung round to point in different directions o The more sophisticated models have variable power o Some dedicated ones can be controlled from the camera o Some can be used in multiple set ups

Controlling the light • Flashguns have a very short light duration, often less than 1/1000th sec o This depends on flash to subject distance • Because of the way shutters work you are limited to a maximum of 1/125th sec or less (check your camera manual) • The controls the flash • The speed controls the ambient light • By juggling these settings you can control the balance of flash to background The power of a flash gun

• The output power of a flashgun is described in terms of Guide numbers o The guide number is the product of the maximum flash-to-subject distance and the f-number that will correctly expose film or a digital sensor with the specified sensitivity. o GN = distance × f-number This simple relationship is well-defined because the brightness of a flash falls off with the square of the distance, but the amount of light admitted through an aperture decreases with the square of the f-number. o The guide number represents an exposure constant for a flash unit. For example, a guide number of 80 feet at ISO 100 means that a target 20 feet away will be correctly illuminated with an aperture of f/4 (80 = 20 × 4) using a sensitivity of ISO 100. For the same guide number and an aperture of f/8, the light source should be 10 feet from the subject (80 = 10 × 8) o Note that most guns quote guide numbers in meters. The same math applies. Inverse square law

• Basically all the inverse square law says is that an object that is twice the distance from a point source of light will receive a quarter of the illumination. o So what it means to us photographers is that if you move your subject from 3 meters away to six meters away, you will need four times the amount of light for the same exposure. This can most easily be achieved by opening the lens aperture two f-stops or using a flashgun that is four times as powerful.

Unfortunately this gets complicated with zoom head guns so it’s best to let the camera do the work An automatic camera will do all the maths for you so, unless you are using manual exposure. It is very useful though to have some understanding of what is going on so that it doesn't come as a surprise when you see the effects of all this in under or over exposed photos. Just remember 'at twice the distance, a quarter of the light reaches the subject'. Aperture Priority

• The algorithms built in to most cameras will try to balance the flash with the available light • This is very useful in daylight when you want to fill in shadows but, certainly with Canon, this can lead to the camera selecting a slow to expose for the dark surroundings • This will lead to a blurry images and be unusable • The answer is to ignore the available light and use manual settings 1/125 and f4-f8 for the average scene Softening the light • The light from flash is very hard and unforgiving • Most photographers soften the light by several methods • Bounce flash o By bouncing the light from a white surface you can give the effect of a much larger surface and softer light. o You can use the wall, ceiling or even someone's shirt to bounce from. o Just make sure that the bounce surface is white, or you will get colour casts o One obvious choice, used by many press photographers is a small plastic cover which spreads the light and diffuses it o There are many proprietary solutions for bouncing the light All do something similar and are a way of getting you to part with your money o I have fallen for many of these ‘sales gimmicks’ over the years and most now reside in an old suitcase to remind me not to waste my money.

Pop-up flash • There is not much that can be done to control the light from a pop up flash • The simplest is a piece of tracing paper or tissue wrapped round the head to diffuse the light • There are a few commercial variants The cheapest and best tool • Here is a foolproof method that I’ve used for many years now: 1. Go along to Hobbycraft and buy a sheet of Fab Foam – this is about 2mm thick roughly A4 sized foam sheet. 2. Follow the instructions on http://www.youtube.com/watch?v=RNCmuExlHvM 3. You can use Velcro for a permanent fix for your flash or you could hold the card in place with a large rubber band Bounce card on camera • Result of bounce card in use Controlling off camera flash • Some of the latest DSLR models have built in controllers for their own make of flashguns • Others have separate flash controllers • There are also independent flash controllers o Some are low cost basic units – others very capable pro grade tools • Extension leads o Allows flash to be used off camera o Limited range • Multi flash o Many flash units will control other similar units by IR or Radio o Mixing units for various makers is often troublesome

Specialist flash solutions • Ring flash o Mostly used for

• Soft Box o Used to diffuse the light directly

• Diffusers o Proprietary name Stofen but many similar units o Softens the light by spreading it out o Often used by journalists o Some flashguns have a small pop out white panel or you can use the old style Press photographers trick by attaching a 5x3” index card to the flash

Studio flash

• You can use most portable flash units to create a home studio • The simplest set up is with a light stand, Flash bracket and white or white/silver umbrella • You can use multiple flash heads to simulate a studio o This leads on into an entire new topic which we can discuss in a later session