BetterPhoto Q&A
Category: New Answers

Tutorial on Flash Work

The problem I had last time I was doing photography, was that I had problems controlling my camera, when I used a Flash. I have a EOS 5 with a 540EX flash unit. When I attach and turn on the flash, the computer gets a mind of it's own.

My problem is that I want a fast shutter speed. Otherwise, I get a properly exposed frozen image from the the flash, but then underexposed "motion blurs" from when the shutter stayed open. (This can even happen when I get 1/60th of a second synch speed)

The other problem, is that focusing is poor when there is poor light, and it tends to focus on totally stationary objects with straight lines- such as curtains behind the person I am photographing.

Basically, I would like to lock down the shutter speed to 1/250th of a second (highest synch speed) and get the smallest aperture that I can afford (f/8 would be good) so that I get better depth of field to address the out of focus problem. I then want the flash to compensate by firing at full power.

Does anyone know how to do this?

To love this question, log in above
June 12, 2002

There are other alternatives, the best being to leave the 540EZ in it's automatic A-TTL/TTL mode and shoot flash pictures in Av (aperture priority) mode. If you shoot with flash in Av mode, setting f/8, then the camera is going to set a long shutter speed to properly expose the background. UNLESS, you set Custom Function 9 to 1, which will force the camera to use 1/200 shutter speed when using the flash and Av mode.

Also check CF7, which controls the AF-assist beam on the EOS 5. Set to 0, it will activate the AF-assist and should make AF possible in total darkness, unless your lens/hood is wide enough to block it.

To love this comment, log in above
June 13, 2002

I played with the camera last night, and found a mode called "X-Sync" where you set the sync speed, the aperture, and the flash shows you the flash is effective to. At the very least, that tells me if the aperture I chose would cover that distance. 1600 speed film should be good to 30-40m at most, which is going to good enough. I was hoping to use a better quality 400 though, but that iss only good between 5 and 18 metres.

The main problem with AF auto assist, is that it is only ever good to 5m or so. I'll be shooting from about 20m (this is a concert)

Well, I wont be devastated if I lose the photos, but on my friend's suggestion, I am bringing two rolls of 1600 and two of 400, and basically, it's motor drive all the way! I should get something that way. (If it's only a overheating flash unit, I'd be a little upset!) This is just a promotional free concert that is only 2 songs long, so I really have to shoot and change quickly.

Wish me luck!

Hey, if you're reading this and intending to go to the Holly Valance promotional concert at Fox Studios, Australia, let me know!

To love this comment, log in above
June 13, 2002

I'm a USAican, so I won't be bumping into you at the concert. :D

Concert stages/performers are usually pretty brightly lit by spotlights. Unless you're using a long telephoto lens, using a flash at 20m (even with 800-1600 speed film) just gets you well lit backs of the heads of the people in front of you. You should be able to get good shots of the performers using 400-800 speed film, no flash, and set the camera for partial metering so that the exposure isn't skewed by darkness around the performers.

AF may improve is you set it to use just the center cross sensor. Otherwise, at 20m you can just set it manually and DOF will probably cover any forward or back movement of the performer on stage.

Good luck and enjoy the concert.

To love this comment, log in above
June 14, 2002

http://www.photo.net/concerts/mirarchi/concer_i.htm

To love this comment, log in above
June 14, 2002