Friday 6 January 2012

EV and Flash output

Its always good to learn something new and i guess we cant know everything, I have mentioned before that i got a Joe McNally DVD for Xmas and i have watched it a couple of times and its great, Very well made, Easy to understand and full of tips, The main thing that i learned was that if you use your flashguns in TTL and use EV compensation on your camera it will affect your flash output even if your camera is set to manual, I have noticed this before but the penny has never dropped, When i shoot in my garden at night i set my camera to manual and say 1/125@F8 i set my flashguns to TTL and adjust the flash output by adjusting the (Flash) EV on my SU800 transmitter-easy but i have noticed that sometimes the flashguns seem low and need extra EV to light the scene, I now realise that the camera had a minus EV set, This has no effect on the exposure as it was set in stone in manual mode but the camera had adjusted the flash output because the camera had minus EV set, So say you shoot in AV and have the flashguns set to TTL, You have both camera and flashguns set to 0 EV and take a test shot, The scene is bright so you dial in minus 1 EV and retake a shot, What has happened is that you have reduced the brightness of the scene but you have also reduced the flash output by minus 1 so to get a flash output of 0 you have to add +1 to the flashgun-simple-well yes once you know and understand whats going on, The good thing is that if you have your camera set to manual and are using multi flash you can increase of decrease all the guns output at the same time by adding + or - EV, This applies to Nikon flashguns so i would like confirmation if this also applies to Canon guns, Most people if asked say that flash is their most understood photographic skill and i am the same, My flash use and understanding has increased 10 fold since using the Nikon system and i feel that i am starting to get to grips with it, It doesnt matter if you are learning from a portrait or wedding photographer the basics are the same, The Joe McNally DVD is expensive but you will learn so has to be worth every penny, Its especially good if you use a Nikon D700 as it shows how to set up a flash system using the built in flash commander which my friend who was visiting had on them so i could play whilst watching the DVD, When i first went over to Nikon a little over 4 years ago i spent a day just playing with the flash, I set up in my living room, I put a vase with flowers on a table and set 4 flashguns around it, I set two to the front to light the flowers and two to the back to light the background, Group A was front right, Group B was front left and Group C was the 2 flashguns at the back, I just turned on the front right, I had the camera set to 1/125@F8 which is what i would use at night, The lights were off and shutters closed so the whole room was dark, Any light in the image would be from the flashguns, I took a shot which lit the right side of the vase, I added or took away light from the flash by adjusting the EV on the SU800, Once i was happy i turned the gun off and turned on the left gun and did the same then turned that one off and turned on the 2 at the back (the SU800 can only have 3 groups) and again took a shot and adjusted the output, Once i was happy i turned on all the guns and took a shot and viola an image that looked like it had been shot in daylight, All the guns being adjustable without even moving from the camera, I now know that if i wanted to add or take away light from ALL the guns at the same time i could just adjust the EV on the camera



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