The Digital World of Photography
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Transcript of The Digital World of Photography
The Digital World of Photography
Lesson 329 Flash : Advanced
Bounce Flash, High Speed FlashBalancing Flash with Ambient Light
Using a Bounce Flash
Why use an external FlashFirst, even the smallest external flash is twice as powerful as the retractable flash. Thus, you have more power for group portraits or subjects posed against the setting sun. Second, a shoe mounted flash is less prone to red eye because it is further from the lens axis. Third, external flashes may be used off-camera on stands or brackets for better modeling and macro work. Fourth, light modifiers, e.g., diffusers or bounce cards, may be employed for softer light. Fifth, flash metering is more acurate. Finally, you may use special features of E-TTL flash, e.g., high speed sync (FP Flash) or flash exposure lock (FE Lock), not available on most popups.
Home Made Bounces
Home Made Bounces
Master Your Camera's FlashOne technique when using a camera mounted flash indoors is to point it behind you. This only works if you have a flash with a rotating head. Stand with your back about three feet from a light-colored wall. This creates a very large light source.
Bounce off wallsBouncing off walls can cause a color shift if the wall is not white. In this case, you will have to custom white balance the flash.
Good use of flashUse a bounce flash
Good use of flashOff camera flash
Good use of flashOff camera remote flash unit
High Speed Flash
Hi speed flashWhen fast shutter speeds are selected, the second shutter curtain begins closing before the first curtain fully opens. The illumination therefore only hits part of the film at normal flash settings. But the FP high-speed sync flash setting fires repeatedly at roughly 50kHz intervals during the exposure to achieve flash synchronization at all shutter speeds. The camera automatically reverts to normal flash firing when the shutter speed is set slower than the flash X-sync speed.
Focal Plane ShuttersAt fast shutter speeds (top) the second curtain starts to end the exposure before the first curtain has fully opened so the two curtains form a slit traveling across the image sensor. Flash would only expose the area uncovered by the slit between the two rapidly moving curtains.
At the flash sync speed and slower (bottom) the second curtain doesn't start to close until the first one is fully open.
FP (Focal Plane) Hi speed flash
FP (Focal Plane) Hi speed flashHi-speed Flash Synchronization (FP flash) Focal plane (FP) flash allows faster sync. speeds than just e.g. 1/200s. With very fast shutter speeds the opening between 1st and 2nd curtain is never as large as the whole film so a single flash burst would lead to a partially unexposed film. As a solution you have to have a constant flash light for the whole exposure time. Unfortunately modern flash units have a peak emisson characteristic so a single flash is not usable for this purpose. Today most manufacturers use a series of high frequent flash bursts (say 50 kHz) with reduced single light emission to simulate a (theoretically) long single constant flash burst.
FP (Focal Plane) Hi speed flash
Good use of flashUse a flash capable of high speed (high sync) fast shutter speeds.
Slow Speed Flash
First or SecondFront or RearCurtain
1st or 2nd (front or rear) curtainMany cameras offer the possibility to synchronize either on the 1st or 2nd curtain. With 1st curtain sync. the flash is fired as soon as the 1st curtain is in upward position while with 2nd curtain sync. the flash is fired just before the 2nd curtain moves upwards. Obviously this means that the natural (ambient) light of a scene exposes the films either behind or before the flash burst. If you shoot e.g. a fast moving object with 2nd curtain sync. you'll get a blurred moving effect which will end in the (flash-) exposed object. With 1st curtain sync. it'll be the other way round.
Master Your Camera's Flash ModesSlow Sync. 2nd Curtain. When the flash fires in normal Slow Sync mode, it fires right away, then leaves the shutter open for a while to expose more of the background. In 2nd Curtain exposures, the shutter opens for a while, then the flash fires at the end, right before the shutter closes.
1st or 2nd (front or rear) curtain
1st or 2nd (front or rear) curtainThe effects of 1st and 2nd curtain flash are most noticeable at slow shutter speeds. To accomplish this either use slow sync mode on your camera or use Shutter Speed Priority Mode and choose a slow shutter speed.
When to use front or rear?Use rear sync when you want the motion to show before your subject.Use front sync when you want the motion to show after your subject.This rear sync image shows the motion before the subject was exposed by flash.
Front CurtainUse rear sync when you want the motion to show before your subject.Use front sync when you want the motion to show after your subject.This rear sync image shows the motion before the subject was exposed by flash.
1st or 2nd (front or rear) curtainWhen using 2nd or rear curtain sync you may get two flashes, one at the beginning of the exposure and another at the end of the exposure.
This is due to TTL flash exposure. The first flash is simply a test flash which gives the camera a chance to calculate the flash exposure values before taking the picture.
Class ChallengeSet your camera to slow sync or place your camera in Shutter Priority mode. Select a shutter speed of about 5 seconds.Turn the room lights off and give the subject a flashlight. Have the subject walk back and forth across the room.Use a tripod or hold the camera very still. Zoom out so the subject has room to walk from one end of the image to the other. Have the subject start walking when you press the shutter release. Be sure to hold still during the entire duration of the exposure.Try it on both first and second curtain modes.
Class ChallengeTry first and second curtain sync on a playing card.Photograph moving match box cars
Balancing Flash with Ambient Light
Aperture and Shutter Speed
Balancing Day and NightNormally when you turn your flash on your camera will automatically set the shutter speed between 1/60 of a second.To correct this you will need to place your camera into shutter or aperture priority mode.
Flash and shutter speedFlash photography is different since it involves split-second bursts of light. A key point to remember in flash photography is that the shutter speed of the camera normally does not have any bearing on flash exposure - an exception being FP mode, mentioned later. Light from a continuous source is affected by shutter speeds, but flash bursts are so brief - in the milliseconds - that a mechanical shutter mechanism has no way of limiting the amount of light from a flash unit that hits the film. Shutter speed only affects the amount of ambient light.
Flash and ApertureTTL controlled flash exposure is where your camera (and flash) work together in automatically controlling your flashs output (as the camera reads it Through The Lens (TTL). Since your camera is controlling the flash output to give you correct flash exposure, your choice of aperture and ISO (and the distance) doesnt have a direct influence on flash exposure. Your flashs power (ie, output) changes to give you enough light for correct flash exposure regardless of the aperture you choose. If you select a small aperture your flash will be more powerful. If you select a large aperture your flash will not need as much power.The aperture setting only effects the exposure if you are using your flash in manual mode.
Flash Sync SpeedThe faster the flash sync. speed ... ...the darker is the scene around your main subject because the ambient light has less influence on the exposure process. The effect is obviously dependent on the level of the ambient light. ... with a moving scene (or a static scene with moving objects) the less blurred are the objects which are not (significantly) exposed by the flash light. etc.
Flash mixed with ambient lightWhen using ambient light, there are two main ways to control light to your camera 1) Shutter speed to control the duration of the exposure and 2) Aperture to control the quantity of light that enters the lens.
Flash exposure, on the other hand, is controlled in a completely different way
Balancing LightLets do an experiment: Setup a subject that will be close to your camera with a background that extends back beyond your subject. Set your camera to automatic and take a picture with flash. Examine the shutter speed and aperture your camera selected. Now, place your camera in full Manual mode and dial in these settings manually. Turn flash off. Take the picture.What does it look like? Too dark right?
Balancing LightLets move on to part two of the experiment: Place your camera in Program mode and turn flash off. Take the picture. The picture should be bright however, if the shutter speed was too slow you may have some camera movement blur. Examine the shutter speed and aperture settings the camera chose. Set your camera to full manual and dial in these settings manually. Turn flash on. Take the picture.What does it look like? It should be correctly exposed.
Balancing LightFinally the last part of the experiment: Manually change your shutter speed to various random settings. You can contr