Flashes demystified… (This one is actually really good, I had help!)
OMG!
Inspired by a post on a photography forum I follow, I thought I’d give you an overview of what it is that a Speedlite flash does for you.
But first, a little disclaimer:
I now absolutely nothing about anything, so if you’re not getting the results that you seek, it’s not my fault, got that, well, do ya, punk?!?!?
I had help writing this article from Kent Bovin, so if anything is correct its his fault, and anything incorrect is my bad.
Kent Bovin is a danish photographer who has gotten famous for among other things, his great articles about flash photography.
Now, on with the lesson.
A flash is basicly nothing more than a torch. It’s a device that lets you add additional light to a scene.
It has several different settings that you can alter, but the basic premise still holds. Its a torch that just happens to fire the light at around 1/1000 of a second, so it’s short lived!
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A flash has x amount of power, the tell tell sign is often displayed on the flash it self or in its name. Let’s use my flash as an example, it’s a Canon 430EX II.
What we’re talking about here is the distance that the flash can project the light at a given ISO setting and aperture aka the Guide number.
f.ex. my 430 EXII flash can project light 141 feet (43m) at ISO 100 at an aperture of 1.0 fully zoomed out to 105mm.
Or it can light up an object 1 meter away at an aperture of “43″…
Heres a scale to help sort out the mathematics…
“But wait, my flash has a guide number of 58, not 64, what to do?” print out the spread sheet cut out each line separately and line up the 1 in “distance” over “58″ in aperture and your’e gold.
“Oh, but wait some more, my camera has ISO 200 as it lowest setting not 100″. Okay, slide the line 1 stop to left.
(just so you know, you dont need to understand all of the above mentioned mumbo jumbo, remember it a torch, a high powered flashlight and thats it.
There’s one thing thats good to know, flash photography is actually two exposures in one.
One using the ambient light usually set to expose the background, and one for the flash usually used to light up the main subject.
Case in point, see the two photos above of the “screaming man”? same in camera settings for both of them, I just added some light to the photo on the right to light up my main subject.
That’s it, get your head wrapped around that and your’e of to the races).
Now lets get down to business, what do all the functions and buttons on a flash actually do for ya?
I-TTL (Nikon) or E-TTL (Canon)
is a setting where the flash together with the camera measures the amount of light a given scene and then decides how much light to put out to illuminate the scene correctly.
Even though the camera/flash decides how much light to put out you can still dictate the amount yourself by changing the EV number up or down, from -2 up to +2 EV….
Manual
Manual is what the name implies a way to manually set the amount of light the flash fires of.
1/1 is full power 1/2 is half power and so on… This is usefull if you wanna be completely sure about how much light the flash gives, without being concerned about the camera dialing the amount up or down without you wanting it to which is what can happen when in E-TTL mode.
Rear curtain sync
Normally when a flash fires it goes of as soon as the first curtain opens, but lets say your’e firing at 1/5 of a second the shutter stays open, the flash has fired but the ambient light is still streaming in.
If your’e taking a picture of a moving object, say a car moving from left to right in the dark with the headlights on, the flash holds the car in place on the left side, but the headlights keep moving to the right so you end up with rays of light moving in a straight line from the left side of the picture to the right.
Rear curtain sync lets you fire the flash just before the shutter closes keeping the headlight rays of light behind the car.
It can also help with portraits, keeping the person super crisp. The idea is that if you take a photo with a shutterspeed at, say 1/15, if this person moves “enough” during the exposure the motionblur that was captured before the flash fired, will be “covered” by the flash afterwards.
At least thats what Joe McNally tells me in his book.
High speed sync
A shutter is made up of two curtains. One curtain moves exposing the sensor/film, while the other curtain follows afterwards covering the film/sensor again.
The time the sensor/film is fully exposed is known as the shutterspeed.
1/50, means the sensor is exposed to light for 1/50 of a second. The curtains moves really fast; so fast that the first curtain is totally gone before the second curtains starts to move.
This works up until speeds of 1/250 of a second.
After that, the second curtain starts to move before the first curtain has finished its movement, which means that the sensor is never fully exposed. The flash only fires when the first curtain is totally gone in “normal” mode, so when you’re above 1/250 of a second you have to havc light througout the shoot to make sure that the entire scene is lit. The flash does this by firing several bursts of light throughout the shot, making sure that each bit of sensor is exposed to the light from the flash.
This dramatically reduces the efficiency of the flash as far as power and distance, but in a tight spot it’ll do the trick.
zoom
Zoom on a flash refers to the ability to concentrate the cone of light. zoomed fully out the flash spreads the light, zoomed fully in the cone of light is fired almost straight forward.
Tilt flash head
Being able to tilt and turn the flash head helps you when you want to bounce the light of a surface espicially with on camera flash. Bouncing the flash of a wall gives you a much bigger light source which in turn gives you softer shadows. This works great indoors with a low ceiling, f.ex. at family get together where you wanna move around without making your family look like a deer caught in the headlight of an oncoming car 
.
Thats it, end of lesson, close your books and get out in real life and try this yourself…
This article doesn’t tell you when to use each setting, thats up to you as a photographer to decide, I’m just telling you how to use it…
These are as far as I’m concerned the the facts of how a flash works. Don’t agree, feel free to comment below.
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about 2 years ago
Cool pic… good work…