Introduction to External Flash Units [PART 2]

Yesterday Tom Pickett from www.tpickettphotography.com began to explore the topic of External Flash Units. Once you’ve read part 1 continue reading the second part of the External Flash Unit series below.

Fill Flash

Now let’s talk a little about fill flash. Fill flash is when you are outdoors for example and the light you are getting from the sun is the main light. Fill flash is just that. Flash that fills in the shadows caused by the bright sun (like those rabbit eyes) on people.

Let’s take a situation. You learned from someone to place people in the shade on bright sunny days. So you have found some shade but there is some strong backlight in the background. You take a shot without the flash on and discover that the backlight has caused your camera to read the backlight, expose for it (and not the subject) and guess what happens? The subject becomes a silhouette. That’s nice if you wanted to make the subject a silhouette but in most cases that is not nice if the subject looks and says, “how come I cannot see me”.

Answer? Fill flash. You turn on the flash, focus on the subject. The camera’s light sensor reads all the light, ambient, background etc. Then, you take the shot again. This time the flash fires just the right amount of light to “fill-in” the subject with the flash produced light. Now you have a rather nice shot where you can see the subject and the background.

That’s not all. The sensors in the camera automatically tell it to look at the backlight, read the value and then the camera tells the flash to produce that amount of light less 1.2 to 1.4 stops below the background light. This algorithm is built in and is automatically done for you. This feature allows the shot to look more natural since we found out long time ago that if you tell the flash to produce the same light value, the result is a “fake” looking photograph. We all should write the manufacturers engineers and thank them for this feature. But wait. There is more.

Let’s now say that the backlight is strong…very strong. What will happen with that? The answer lies in your camera in what are called custom functions. You simply go to your custom function menu and find the one that says “auto reduction of fill-flash” and turn it OFF. (It is always on until you turn in off). The result is the flash puts out a full burst and is no longer reduced. Result? Another properly lighted shot!

For those of you lucky enough to have purchased a high-end flash unit such as the Canon 580, you can also pump up the light output directly on the back of the flash unit to increase the duration thereby yielding the same result of turning off the auto reduction in the previous paragraph. You can also tell your camera to instruct the flash to give you more output. This is covered in your manual and is called flash-compensation. You can increase or decrease the amount of flash by using the camera’s built in flash compensation by as much as two f-stops of light either way…up or down.

Consult your manual as it differs from manufacturer to manufacturer.

Dragging the Shutter

Let’s talk about “dragging the shutter”. You saw me mention that above and you thought what is that? Dragging the shutter sounds awful, damaging doesn’t it. Well not really. It is a little trick that once you learn how to do it, you will always use it in situations that come up….and I can assure you they come up.

Set up the situation here…you are photographing a wedding inside a dimly lit church. You have your flash to take the photos. But you notice that the altar, which is dimly lit, is not being picked up by your exposures. Your subjects are.

The answer is to revert to using very slow shutter speeds. Since your main light is your flash, the ambient light around the altar is not being lit by the flash. But if you lower your shutter speed to say 1/15 or even 1/10 and then take the same shot, magically the camera picks up the ambient light around the altar. But let me warn you here that at this point you must use a tripod for this since at these shutter speeds, any movement of the camera by you (you cannot hand-hold a DSLR using 1/10 sec shutter speed) will result in very blurry altars. Buy yourself a nice tripod and try this. It really makes a nice effect. So now you know what “dragging the shutter” means….you have dragged it down to slow speed shooting.

High Speed Flash Photography

Many of you have e-mailed DPS wanting to know more about high-speed sync in flash photography. As you probably know, most DSLR’s (and most any kind of SLR, digital or not) have a maximum flash sync speed. It is generally in the area of 1/200 shutter speed. Very few have lower, some slightly higher. To find yours, refer to your camera specifications in your owner’s manual.

This sync speed is the maximum your hot shoe flash will sync and provide you with properly exposed images. But wait. There is a method to override the limits again thanks to the engineers.

Sometimes, when you are outdoors and are shooting portraits you would like to shoot at F4 or even F5.6 to get that magic blurred out background which then lets your photo viewers focus on the subject, not all the trees and objects behind the subject. But when you put your camera in AV mode, dial in an aperture setting of F4, you find your camera wants to set a shutter speed of 1/1500 or more. Whoops! Flash won’t sync at that speed, right? Wrong!

Every good DSLR should have an override custom function on it that allows shutter speeds exceeding the maximum sync speed set by the factory. It is there. Check your manual. On Canon units, it is in the “custom functions”. Once you have discovered how to override the max sync speed now you need to look at the back of your flash unit and you will find a mode called FP sync or just FP. On Canon units, it is a little lightning icon followed by the letter H. When you slide the switch or otherwise get it to this mode, a little lightning icon will appear in the viewfinder.

Now, you can go ahead and shoot at F4 with shutter speeds up to the max the camera has available. And you still achieve that precious look that we all want; a portrait with a blurred background.

Flash Exposure (FE)

Finally, let us take a look at another valuable feature that is often never used but once you learn how to use it, you will never forget it. I am referring to the FE (Flash Exposure) lock feature found on most cameras. FE lock is simply obtaining a proper flash exposure, pushing the right button to lock in that exposure. You then have about 16 seconds to recompose and take the shot thereby guaranteeing the exposure you set and not have the camera reset a new exposure ruining your shot.

I use this feature very often especially at weddings where you expose and lock the exposure then recompose and take the shot. You locked the exposure hopefully on the brides face or the grooms face then recomposed. The result will be perfectly exposed faces or dresses or whatever you locked in from the start. There is nothing worse than a shot of a $5,000.00 wedding dress with all the highlights overexposed.

On Canon units, the FE lock is the asterisk button (*) directly below the display screen on top of the camera. To make this work, use the partial metering mode (or spot metering mode) over the subject where you want to lock the flash output then press the asterisk (*) button. The speedlight will pre-flash that area and lock that exposure into memory. I might caution you that you have 16 seconds to then recompose and take the shot. If you find you need more time just press the (*) again and again until you feel comfortable with the composition. Each time you press the (*) button the unit will fire another pre-flash.

If you use this, remind your subjects that they will see two flashes. I tell them that the first flash is me telling the camera what to do. Then when I am ready to take the shot with the second real flash, I warn them that now comes the real shot and flash. This way, you avoid them thinking the shot was taken with the “pre-flash” then moving. Incidentally, this also works with the built-in flash unit on all Canon DSLR’s!

An Essential Accessory for External Flash Units

In closing, let me tell you about an accessory you should add to your arsenal as soon as you can for your speedlight. This is called an off-camera flash cord. It is expensive (about $65.00US) but is worth it. It allows you to remove the flash off the hot shoe and hold it away from the camera and still maintain E-TTL operations. Moving the flash “off-shoe” allows you to get really creative with your flash unit.

Frankly, I have just touched the surface here in this article on flash units for your DSLR. Many of us pros (including me) continue to use manual flash units to gain even greater control over lighting. But that is a whole new area that should be covered by itself. If you check out a Canon 550 or 580 unit, you will see that it does allow the user to set it to manual operation as well which backs up my statement that manual use of cameras and flash units is where we pros like to be….but for beginners and intermediates, I highly recommend the use of those geniuses at the factory that allow us to automate our shooting as much as possible.

Good shooting to all of you.

See more of Tom’s work at www.tpickettphotography.com