"MODE" button to cycle through the choices until you see "M" modeOnce in Manual mode, you can adjust the flash intensity to one of six power levels by pushing the"+" or the "-" button until the desired power level is displayed on the LCD:z 1/1 Full power for M modez 1/2z 1/4z 1/8z 1/16z 1/32 Minimum power for M modeUse a handheld flash meter to determine the power setting which will produce correct flashexposure. If you do not have a flash meter, you can get an approximate idea using simple GuideNumber calculations:a) Measure the flash-to-subject distancee.g. 2 metresb) Multiply the flash-to-subject distance by the aperture setting on your lense.g. for f/11, multiply by elevenc) Express the product as a fraction of the Guide number of the flash. For ISO 100, the guidenumber is 43m.e.g. 2 m times 11 equals 22m, which is very close to half of the Guide number for the flash,43md) Set your flash power to the result fractione.g. 1/2 powere) Check your result. Usually, some adjustment is required, since the actual guide number maydiffer from the value specified as ideal.When using a Digital SLR, check your histogram to make sure that highlights are not blownout.f) A new setting is required only if you change the aperture or the flash-to-subject distance.SynchronizationThe flash is normally synchronized to the OPENING of the shutter. If you wish to synchronizeflash to just before the CLOSING of the shutter, select "2nd curtain sync" by pushing the "+" andthe "-" buttons together."2nd curtain sync" is indicated on the LCD panel by a symbol with three triangles.StroboscopeThe flash normally emits a single burst of light during each exposure. For special effectphotography, such as multiple exposures to show a sequence of motion, you can cause theSpeedlite to emit several bursts of light.A-TTL -> M -> M MULTI ->Guide Number (ideal)ISO 24mm 28mm 35mm 50mm 70mm 80mm100/21° 25 m 27 m 30 m 35 m 40 m 43 m200/24° 35 m 30 m 42 m 50 m 57 m 60 m400/27° 50 m 34 m 60 m 70 m 80 m 86 m800/30° 70 m 60 m 84 m 100 m 114 m 120 mPagina 4 di 8EOS Documentation - 430EZ