unfortunate group of people getting their picture taken at the bowling alley by someone with their pocket camera: "the flash didn't go off!"
picture taker: "oh sorry let me take it again"
unfortunate group: "the flash didn't go off again!"
picture taker: "ummm, i don't know why this dumb thing isn't working. let's go see what these bowling shoes look like under the black lights!"
that probably sounds like a familiar conversation you often find yourself in. why doesn't the flash go off? why do we care so much about the flash? when a camera flash fires, it lets off an extremely intense and very short burst of light. the shutter opens up before the flash fires and closes when it's done. if you want to understand what the camera sees during a flash photo, grab a friend and go in a windowless room in the house where it's pitch dark. have your friend stand on the other side of the room and wave their arms like a maniac. stare in the general direction of your friend making a fool of themselves and flip the room light on and back off again one time as fast as you can. on off. what did you see? if you did the light fast enough, you saw a quick snapshot of your buddy with their arms in a fixed position even though they were in constant motion. for the split-second that the light was on, their arms didn't move too much, so to you it appeared that they were still. that's what the camera sees (and records) on a flash photo. this is why it's near impossible to get ghosting or motion blur in a photo using flash. that's a good thing. on point-and-shoots, flash is your friend, quite possibly even your best friend.
if you have a good enough dslr, enough light, a fast enough lens, and have read the other posts in this mini-series, then you should be able to take a photo of motion and freeze it without using flash. otherwise, flash does the job.
another common flash issue is that it turns your friends into evil looking monsters by making their baby blue eyes into red scary fireballs. the cause of redeye is not a mystery, contrary to what paranormal seekers would like to believe. it's simply a reflection of the back of your eyeball, specifically the blood vessels on the retina, when hit with direct and intense light. if the flash is off-axis with the eyes, then your redeye will disappear. i understand with a point and shoot this is difficult to acheive because the flash is fixed and it points in whatever direction the camera is pointed. newer cameras have various methods of redeye reduction built into them which all but eliminates the problem. if you have a dslr with a speedlight (one of those add-on flashes stuck to the top of the camera), then you can modify the direction of the flash. point that thing at about a 60 degree angle toward the ceiling and you'll get a nice bounce to illuminate your subject and get rid of redeye. if you have a speedlight, do a lot of experimenting with bounce angles. you'll be surprised to see the differences in the various angles.
another nice way to soften the light is to use a diffuser. you can buy one for anywhere from three to probably over a hundred bucks. you can also use a piece of wax paper or tissue paper, even kleenex or toilet paper. be creative - when it comes to lighting it sometimes helps to be unorthodox and try weird stuff. place whatever material you have over your flash and see what the results are. anything goes, as long as it's not completely opaque. you can even use colored material for strange pictures if you feel so inclined. diffusers work great, but i don't recommend spending a lot on one. i bought one that fits on my sb-600 speedlight and it cost me $2.99 on ebay. i would argue it works just as well as the $100 version. it's not rocket science, just plastic. some things are worth spending the money on - this is not one of them. put the saved money toward a better lens.
the rest of this post is exclusive to dslr cameras. i haven't yet seen any point-and-shoots with the option to adjust the following parameters, but i suppose they could exist. external speed lights allow you to change the intensity of the flash. this is handy if you want to use flash but not have it overpower the photo. this can allow you to obtain subtle highlights without it looking unnatural. again, play around with it, it's the only way. here's a couple photos that show the difference between direct flash and bounced flash. notice how the direct flash photo has underexposed areas around where the flash directly hit and the indirect flash photo doesn't. also notice the section of my basement that has a bunch of random stuff.
there are usually two main flash modes available. one is front curtain and the other is rear curtain. the term curtain comes from old analog camera technology that we won't go into. what it controls is if the flash fires right after the shutter opens or right before the shutter closes. the easiest way understand the effects of this is just to see it. both of the shots were taken with a 2 second shutter speed while panning the camera from the right to the left. check out the photos:
what's happening is that the floor and the candle get captured when the flash fires, but the flame is captured throughout the two seconds because it is its own light source. when the flash fires at the beginning of the shot, the flame lags behind the candle. when it fires at the end of the shot, it captured the flame already and ends the shot with the candle.
one last thing worth mentioning is something nikon builds into their speedlights and higher end cameras called the creative lighting system. it allows you to set up a bunch of speedlights in a room and wirelessly fire them from the camera. this lets you get all sorts of cool light angles, but you have to own multiple speedlights (a few hundred dollars each) and a camera capable of commanding the speedlights. i believe canon just recently came out with a similar capability, but i primarily shoot nikon so that's what i can speak to. if you end up diving into that world and you're stuck, drop me a line and i can help you get it up and running.
i really do intend for these posts to be short when i start them but they end up growing pretty large by the time i'm done. trying to keep it basic but i also want to be thorough. questions? let me know if anyone tries anything funky for a diffuser...
next up: dynamic range/HDR