KIKA MULITZ LIVNO: Flash Light

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Sunday, August 1, 1982

Flash vs Continuous Lighting by Morris Studios

Saturday, August 1, 1981

Speedlite 580EX II's External Automatic Flash Exposure Sensor And Your EOS Camera

Canon’s latest high-end Speedlite 580 EX II has a couple of features long requested by serious amateurs and professionals. One of these is an external automatic flash exposure sensor, which provides the option of automatic flash – but not TTL (Through The Lens). Instead, the flash controls its output similar to older “thyristor” flash units many pros used in years past.

The Speedlite 580EX II now has an external automatic flash exposure sensor - a great option for different types of shooting

Far from being a throw-back to the good old days, this is a viable option for different types of shooting. One example is providing automatic exposure when a flash is positioned off-camera, especially if it’s triggered by a third-party radio or infrared remote system. Likewise, it will provide automatic flash when triggered by conventional flash slave. Additionally, some users may find that it provides less fussy and more consistent flash exposures for ordinary on-camera flash with indoor scenes where you aren’t trying to balance flash and ambient light.

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Traditional non-TTL automatic flash:

The Canon Speedlite 580EX II can perform this with any EOS camera, film or digital. We’ll explain how to set the speedlite to this mode in a moment. With yesterday’s “thyristor” type auto flashes, the photographer would dial-in his or her ISO setting on the flash unit, and in some cases, would also choose one of a few available distance range settings (for instance, the popular Vivitar 283 flashes had a red color-coded range, good from about 3 to 30 feet for direct flash). A little scale told the photographer where to set the lens aperture when the flash was set to a particular distance range. The flash would vary its output by literally using its front-facing sensor to read reflected flash illumination as it returned from the subject. When the sensor “thought” enough light had returned, it instantly sent a stop signal to the flash. The result was brief flash durations when close to a subject, and longer, brighter durations when shooting something farther away.

This type of automatic flash has worked for many photographers for several decades. While there is no question a modern TTL flash and camera can combine to perform tasks simply not possible using an external flash sensor (like automatically balancing ambient and flash exposure), auto flash using an external sensor is a proven method of flash exposure control. The Speedlite 580EX II now gives users this option.

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Setting external auto flash with the 580EX II using the EOS-1D Mark III:

This can seem tricky, since simply pressing the flash unit’s Mode button will not call up the external flash options. To do this, you must activate the 580EX II’s flash custom functions. With the EOS-1D Mark III camera, this is easy – you can do it from the camera’s Menu (2nd Set-up Menu > External Speedlite Control > Flash C.Fn settings > 3: External metering: Manual.). Don’t be fooled by the wording on the Mark III’s menu; this is still automatic exposure flash, using the flash’s external metering sensor. It’s not manual flash exposure – that’s done with the flash’s Manual mode!

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(Simulated Displays) Follow these three easy steps to set External Auto Flash on the Speedlite 580EX II while using an EOS-1D Mark III
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Setting external auto flash on the 580EX II with other EOS cameras:

1. Press the illumination/C.Fn button on the back of the 580EX II for at least two seconds until the speedlite’s display changes.

2. Turn the flash unit’s control dial until “Fn 05” (speedlite Custom Function 5) appears.

3. Press the speedlite’s SET button to make the second digit blink on and off; while it is blinking, turn the control dial on the flash unit until option 3 appears (Fn 05-3). By doing this, you have now set the flash to perform standard, traditional external flash metering. This can be done with any EOS SLR, film or digital.

Using the standard External Metering -- Manual mode:

in spite of “Manual” appearing in the wording, this mode does indeed provide automatic flash exposure, using the 580EX II’s external flash sensor. “Manual” means that most communication between flash and camera no longer takes place, and the user must make the settings detailed below.Once set, a letter “E” appears in the upper-left corner of the flash’s LCD panel (if “E-TTL” still appears, you didn’t set external automatic flash control...try again). You’ll also see an ISO indication, and the aperture (“F-5.6” or whatever aperture number the flash is currently expecting). Below this is a distance range scale, in either feet or meters (change it to feet with flash Custom Function 0-1).
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A letter "E" appears in the upper left corner of the LCD display when setting the Speedlite 580EX II to External Metering: Manual Flash Mode

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Like traditional auto flashes, when the 580EX is set to the External Metering: Manual, the flash has almost no communication with the camera body. The only exception is that you’ll still get a ready light in the finder, and the auto zooming of the flash head to match the lens in use still functions with EOS digital SLRs.

The photographer must set the following manually:

a) ISO on the speedlite

b) Aperture on the speedlite’s LCD display

Once these are set by the user to match the camera’s settings, the flash’s distance scale will update to show you the distance range you can shoot with automatic flash control. The flash’s zoom head will adjust automatically to match the focal length of the lens in use. The camera should be set to its Manual exposure mode in most circumstances. Since the flash and camera are not working in tandem to control overall exposure automatically, it is risky to set Av mode and hope to properly expose the ambient light along with flash illumination. Generally, a fast sync speed like 1/200th or 1/250th of a second is used; it is impossible to set faster shutter speeds if the speedlite is on. Hi-speed flash sync mode will not operate in external automatic flash mode. Ignore the camera’s analog metering scale in the viewfinder – it is reporting how your current settings would expose ambient light, not flash.

Manual mode on the EOS-1D Mark III is the primary choice for non-TTL auto flash, using the speedlite’s external sensor
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Other EOS camera settings to consider:

Do not use the P-mode or Tv mode, since these set aperture automatically, and the flash has no way of knowing what aperture the camera is using.The External metering: Manual mode is the only type of external sensor auto flash that will work if the Speedlite 580EX II is used off-camera, and triggered with either a PC cord or a non-dedicated type of remote controller or standard photo slave unit.

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Deliberately under- or over-exposing flash in External metering:

Manual modeIf you want flash exposure to intentionally be greater or less, you have to do one of two things: set a different camera lens aperture than the one you’ve set on the back of the flash, or change the camera’s ISO to a different value than the one you reported to the speedlite.In other words, if you take a picture with all flash settings matching the camera settings, and the first shot looks too dark, you can brighten flash exposure by:1) Setting a wider lens aperture than what you set on the flash (example: flash says f/8; you set the camera to f/5.6 to brighten exposure one stop).2) Raise the camera’s actual ISO above what you’ve set on the flash (again, to lighten the exposure, if the flash’s LCD panel is set to ISO 100, setting the camera’s ISO to 250 would deliberately over-expose by 1-1/3 stops).

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EOS-1D Mark III and the Speedlite 580EX II:

The newest Canon EOS digital SLRs* add another method of using the external flash sensor on the 580EX II. In this instance, the flash and camera do communicate extensively, so the aperture and ISO you set on-camera are immediately relayed to the speedlite. Automatic flash is still controlled by the flash’s external sensor; the user still sets shutter speed and aperture (as well as ISO) – on the camera body only. Manual mode on the camera is again ideal; theoretically, the aperture-priority Av mode can be used, but there’s the risk of problems with exposure balance as well as shutter speeds that are too slow for safe hand-holding when indoors.

(Simulated Display) EOS-1D Mark III menu navigation C.Fn 05-2 allows a user to set external metering for Automatic External Flash
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Using the EOS-1D Mark III, this is the 580EX’s Custom Function 05-2 – External metering: Auto. In this case, “Auto” means that the camera can communicate its settings directly to the speedlite as you set them. Once set (you can also use the camera’s External Speedlite Control menu to set flash C.Fn 05-2), the ISO read-out disappears from the 580EX II’s LCD panel (it’s always the same as that on the camera).

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(Simulated display: Manual Mode) When setting the Speedlite 580EX II to External Metering: Auto mode, the ISO read-out disapears and is not accessible
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Unlike the External metering:

Manual setting, the Auto option with the Mark III does allow you to use the P-mode or Tv mode on the camera. Automatically-set apertures in these modes are instantly communicated to the speedlite. This only happens, however, if the flash is either mounted on the camera, or attached via the optional Canon Off-Camera Shoe Cord. With External metering: Auto, the distance display is updated in real time as you change ISO or aperture on the camera. One fundamental difference, though is that you cannot intentionally over-expose or under-expose flash by simply changing aperture. Unlike with the “External metering: Manual” option, as you change apertures, speedlite power adjusts to keep flash exposure constant. Opening up the lens aperture means you increase the possible maximum distance you can shoot out to, but does not simply lighten the overall flash exposure. Instead, you must use Flash Exposure Compensation (either on the camera body, or at the speedlite). The procedure is the same as if you were using E-TTL and applying Flash Exposure Compensation.

One other note:

Neither type of external sensor auto flash can be used in Canon’s Wireless E-TTL mode. As soon as you set a 580EX II into either “slave” or “master” settings, the External Auto setting immediately reverts back to E-TTL on the flash’s LCD panel. External sensor auto is impossible to set.

(* EOS-1D Mark III only, as of July, 2007)

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Switching back to E-TTL:

Once External flash metering has been set with the 580EX II’s flash Custom Function 05-2 or 05-3, to revert back to E-TTL, you cannot just push the flash’s mode button. Instead, you must re-set Flash Custom Function 05 to option “0” (E-TTL II). Do not set the “TTL” option with digital SLRs. With the EOS-1D Mark III, you can again do this using the camera’s menu, under External Speedlite Control. With other EOS digital SLRs, you must engage the flash’s Custom Functions via the speedlite’s C.Fn button, navigate to Fn 05, and set it to “Fn 05-0” on the speedlite’s LCD panel.

(Simulated Display) To change from External Sensor auto back to E-TTL, user must set Flash Custom Function 05 back to "0"

The External flash sensor:

One thing for experienced users to keep in mind is that the external sensor on the 580EX II measures a relatively narrow 20-degree angle of view. This never changes, regardless of the lens that’s on the camera (a fundamental advantage of TTL flash metering). The 20-degree view means the flash measures an area that’s about the same as that covered by a 135mm lens (on a full-frame camera). This may be a “tighter” metering area than what users may be accustomed to with previous-generation “thyristor” flash units. Keep this in mind when evaluating flash exposures in external sensor mode.

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Summary:

The external automatic sensor option with the 580EX II flash is one that many photographers will want to experiment with, at least from time to time. It will certainly prove useful in some circumstances, such as removing a flash from the camera to light up backgrounds or other subjects from an angle. And some users may find they prefer its exposure characteristics in general to those of E-TTL in ordinary indoor candid situations. E-TTL is still going to be vastly preferable for balanced-fill flash outdoors, or for balancing ambient light and flash indoors in Av and Tv modes. And the external sensor auto mode, as discussed previously, will not work at all with Canon’s Wireless E-TTL flash system. Whether you own the latest EOS cameras or not, external sensor auto flash is easy to experiment with using the 580EX II speedlite, and adds a new versatility that EOS users have requested for some time.

Links » CANON USA

Fill-in flash use with EOS cameras and speedlites

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Balanced fill-in flash is a wonderful technique that can either add life to otherwise ordinary pictures, or in some cases, rescue images that previously might have not been useable. And what’s really nice is that fill-in flash can be done with fully automatic exposure control – no special manual settings are needed, unless you want to put your own personal touch on your pictures. You can even do fill-in flash using the built-in flash unit on cameras like the EOS Digital Rebel series and the EOS 30D. Photographers use different terms to describe this technique. Fill-flash, fill-in flash, balanced-fill flash, and so on all refer to the same thing.
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What exactly is balanced fill-in flash?
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By definition, a fill-flash picture is one in which the ambient light in the background – sunlight outdoors, room lighting in an indoor shot, and so on – is properly exposed and therefore normally visible in the picture. But along with this, flash has been used, and subjects in the foreground of the picture are illuminated by this extra burst of flash. With a properly exposed background, and also a flash-illuminated subject that’s got proper flash exposure, the two light sources (flash and ambient light in the scene) are balanced, and neither will appear overly dark or light. This usually gives us a very natural-looking picture. It can also brighten otherwise subdued faces, lighten shadows from harsh sunlight, or sometimes just add a little sparkle in a subject’s eyes

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No Fill Flash

Fill Flash using 580EX

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First off, there’s no special trick to taking balanced-fill flash pictures outdoors in daylight, even in bright sunlight. With the camera in any automatic exposure mode such as Program (P), Tv, or Av, just pop-up the built-in flash by pressing the flash-on button, or alternatively mount and turn on an EX series Canon Speedlite flash unit. The camera “knows” the flash has been activated, and all you need to do is focus and shoot the picture. In the Tv and Av modes, if you’ve set a shutter speed (in Tv) or aperture (in Av) that simply won’t enable a proper exposure of the daylight in the scene, the opposite value blinks on and off in your viewfinder; just switch to a different shutter speed or aperture, until the display stops blinking on and off. You’re ready to take the picture.

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There’s no need to take the flash out of its automatic “E-TTL” setting (unless for some reason you want to use manual flash with an accessory EOS speedlite). The beauty of fill-in flash with a modern SLR is that the camera adjusts background exposure and flash exposure automatically, with little input required from the user.

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To preserve a natural look in fill-flash pictures, the camera deliberately tends to reduce the intensity of your flash output when it detects that you’ve properly exposed the ambient light in your background. The intent is to give you fill-flash pictures with foreground subjects that don’t appear to obviously have been blasted with frontal flash. (This occurs automatically, with no input required from the photographer.) This way, shadows are gently filled-in, without looking like your subject was lit-up by a searchlight.

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When you have a subject that is primarily lit by sunlight, and you’re just trying to lighten a few shadows on his or her face, this automatic flash reduction tendency works very well. But sometimes, you may be asking the flash to do more than just fill-in a few shadows. If your subject is heavily back-lit, and entirely in shadow, you may want the flash to become the primary source of light. An example might be a shot of a person against the setting sun. With no flash, you’d likely get a silhouette. But if you simply turn on your flash and take a picture at normal settings, you might end up with an effect that still looks like a silhouette. The flash may not have lit your subject up much at all. What when wrong?

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Fill-in flash pictures in daylight:

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Using Flash Exposure Compensation in fill-flash pictures:

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The amount of flash illumination in a fill-in flash picture is a starting point. And while it often works beautifully, in instances like the sunset shot, all the bright sunlight in the scene can fool the camera into thinking that not much flash is needed. But as we said, in a totally back-lit scene, you’re basically asking the flash to be the main source of light hitting your subject. How to get more flash on the scene? Easy. Use your camera’s Flash Exposure Compensation. All EOS Digital SLR cameras, with the exception of the original (6MP version) of the EOS Digital Rebel, have this feature. And it’s also available on most of Canon’s accessory speedlites, like the 430EX or 580EX. By deliberately adding “plus” up to two stops of flash illumination, you’re intenionally brightening the flash output. Don’t be alarmed or surprised if you find that you need to use Flash Exposure Compensation from time to time in fill-in flash pictures. And remember if you think the flash output in your fill-in shots is too much, you can also use Flash Exposure Compensation’s “minus” settings to reduce it. One last thing: Flash Exposure Compensation affects only the flash output. The ambient light in your background will remain unchanged as you adjust Flash Compensation.
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All EOS digital SLRs also have “standard” Exposure Compensation as well as Flash Exposure Compensation. Exposure Compensation lets you deliberately lighten or darken the ambient lighting in the background. It’s entirely separate from Flash Exposure Compensation, and has absolutely no impact on how much flash output strikes your subjects. It solely impacts the ambient light in the scene. It’s another very useful control which gives you very complete command over the look of your fill-in flash pictures. It’s particularly useful when balancing flash with low light, indoors or outside at night (see below).

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Remember that if you’re outdoors in daylight, your flash is competing against a mighty strong opponent – the sun. Don’t expect fill-in flash to be effective when you’re too far from your primary subject(s). In sunlight, the built-in flash really loses most effectiveness in fill-in situations when you’re much more than 6 or 8 feet (2-2.5m) from your subject. Accessory speedlites like the Canon 430EX or 580EX will reach farther, but may be against their limits if you’re trying to light up a back-lit group picture from more than 15 or 20 feet (4-6m) away. Even if you boost flash output with the Flash Exposure Compensation, any flash unit has a maximum amount of power it can deliver, after which it simply can’t produce any more flash power.
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Limits with fill-in flash in daylight:
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Overcast No Flash
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Overcast Flash ON
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Changing the brightness of the background:
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Balanced-fill flash can also easily be done when you’re indoors, or outdoors at night. In a typical flash snapshot in these conditions, we’re used to seeing a brightly-lit subject, with a black or nearly-black background. This happens because the ambient light in the room or in the scene was underexposed, but the flash illumination on the subject was correct. To get a more natural-looking, balanced-fill result in these scenes, we need to extend the exposure so that more ambient light is recorded in the scene.

This means one of three things, or a combination of them: raise the camera’s ISO setting, and/or shoot at wider lens apertures (a lower f/number), and/or shoot at slower shutter speeds. Again, EOS digital SLRs can automatically perform this task for you. The simplest way is by changing your exposure mode to the Av mode, or the Tv mode (in the latter case, you must also select a fairly slow shutter speed). In either mode, the camera will always try to properly expose the ambient light in your background, no matter how dark it is – if your chosen settings won’t allow this, the speed or aperture (whichever you’re not setting) will blink on and off in your viewfinder. And keep in mind that none of this is possible in P (Program) mode, or the full-auto “green zone” setting. In those modes, to avoid possible blurs, the camera never allows shutter speeds slower than 1/60th of a second when you use a dedicated flash.

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Raising your ISO to something like 400 or 800 will give the camera more light-gathering power when you’re in low light, and will minimize the use of extremely slow shutter speeds in Av or Tv mode with flash.
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There’s another even simpler option – on cameras like the Digital Rebel series, or the EOS 20D and 30D, there’s a fully automatic mode called “night portrait” on the camera’s mode dial. Set it there, and the camera will allow slow shutter speeds with flash to blend in ambient light.

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Any time you’re working at slow shutter speeds to blend-in natural light in a flash picture, remember to be careful to hold the camera very steadily, and be sure your subjects are stationary as well. Any movement will usually result in blurs or ghost images. In other words, if you’re looking for sharp action pictures with flash at a high school basketball game, it’s not the time to use the balanced-fill technique.

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Again, the camera will usually tend to reduce the flash output when you properly expose your backgrounds, so that the flash isn’t obvious in the lighting of the final picture. Often, this gives a very natural looking result. But if you want more or less flash output, you can easily achieve this with your Flash Exposure Compensation. And you can also subdue the ambient light in your background by darkening it with standard Exposure Compensation, or alternatively brighten it by adjusting Exposure Compensation in the “plus” direction. Once again, this is entirely separate from adjusting flash power up or down with the Flash Exposure Compensation. Experimenting with the two will give you a tremendous amount of control over the final look of your fill-in flash pictures.
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Natural-looking flash pictures in low light:
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Av mode with flash

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P Mode with flash

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The bottom line:
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Don’t be afraid to use your flash in daylight – it’s actually one of the most effective times to use it, as long as you’re not too far from your subjects. And in low light, don’t feel locked-in to 1/60th of a second shutter speeds, and resulting unnatural dark backgrounds. Experiment a little with the balanced fill-flash capabilities of an EOS digital SLR, and you’ll probably be quickly convinced of its usefulness.

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Canon 580EX II Flash Setting - High Speed Sync

Image from the manual:

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Note by © cgardner: HS Sync will not work in auto mode because the sensor controls the flash exposure in real-time vs ETTL which sets flash power in advance of the actual shot based on the pre-flash calculation.People, even very skilled ones, tend to dismiss techniques they are not very familiar with. "Stobist" for example completely dismissed TTL flash on silly "ethical" grounds and thus never really used it enough to learn how to use it effectively, but is apparently starting to warm to the idea since he used a set of radio popper radio triggers. I started with completely manual flash in the early 1970s used "auto" flashes (Vivitar 263, 283 and 285HV) for many years. The idea of using a tiny sensor window on the flash worked OK in the days when prime lenses with identical FOV and negative film with 1-2 stops latitude for overexposure were used, but that 30 year-old technology isn't ideal for digital which requires precise exposure for highlights. Auto mode reacts to the overall scene and while it handles "average" and static scenes well it can't correctly expose highlights correctly many situations with the precision needed for digital. When I bought my first Canon 20D in 2004 I initially used my pair of Vivitars but soon switched to a pair of 580ex, primarily for the HS Sync outdoors. I found that I had to completely relearn flash exposure to use ETTL flash effectively. The key was understanding how the camera evaluative flash metering works in Canon cameras. The Canon evaluative metering introduced around 2004 (20D and later models) evaluates ambient and pre-flash across 35 different zones between the time you mash the shutter button fully and the shutter opens. By comparing ambient and pre-flash reflection it can make a logical guess how far things in each zone are from the camera (nearer objects will reflect more light) and their relative importance (more weight given to zones in the middle of the viewfinder). The camera then will try to preserve the detail in the brightest highlights. The biggest problem people starting with flash seem to have is relearning how to compose for flash. Flash exposure is only correct at one distance. It is physically impossible to put something in the foreground to frame a shot, as you can with ambient light, and not have it fool automatic metering, which simply reacts to the reflected light. Obviously if you have something very reflective in the foreground the flash adjusted for it will underexpose the background, so the best way to compose for flash is to ensure what you need correctly exposed is in the foreground and that everything you want correctly and identically exposed is the same distance, including body parts when setting up a pose. For example with flash if you set a pose where the shoulder is closer to the flash than the face either the shoulder will be correctly exposed and face underexposed, or the face correctly exposed and the shoulder overexposed.ETTL does a fine job of fill flash. You simply need to adjust FEC as needed for each different scene reflectance.Evaluating exposure based on what the camera actually recorded in the last shot is much better than relying on a sensor in the flash. Learn to use the overexposure warning (OEW) to monitor exposure . It will tell you both when and exactly where the highlights are overexposed. My workflow is quite simple: Point and shoot, evaluate the OEW in the playback and adjust FEC as needed on a ongoing basis. In static shooting situations such as portraits where the subject / flash distance does not change it is more effective to use M mode rather than ETTL. The workflow is exactly the same - shoot, evaluate, adjust - but what is adjusted is power level directly, not via FEC setting. But once set the exposure will not change because the camera metering isn't involved. If you click the WWW button below it will link you to my tutorials which explain Canon flash. In one of them I compare the 18 different ambient / flash metering combinations my 20D offers.

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Note by © dmward: A friend who uses Nikon made the same comment about WC regarding TTL.

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I think your problem is that Auto on Nikon speedlights is essentially the same function as High-speed synch on Canon speedlights.

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For both the concern is finding a way to get the speedlight to illuminate the whole image when the shutter speed creates a moving slit across the sensor.

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For Canon its High-speed Synch, for Nikon its, Auto. The result is the same, a "flashing" of the speedlight to ensure the image is evenly illuminated by the flash when the shutter speed causes a shutter curtian slit.

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I use Canon, and the High-speed setting on the 580EX does a good job filling shadows outside.

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It is possible to use a combination of EV compensation adjustment in the camera with FEC on the speedlight to "darken" a sun lit background while "popping" the subject with the flash.

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It is important to remember that the effective GN is reduced because of the high-speed synch so you have to be closer to the subject.

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" I'll have to review Will Crockett's DVD, but I believe he was claiming the ETTL is not as consistent in getting proper exposure and suggested auto flash as a better alternative. I don't recall if he was speaking of shooting outdoors or indoors. I'll have to check."

Note by © cgardner: Both ETTL and Auto (sensor on flash) both react to the light reflecting from the scene. The difference is evaluative flash metering reacts to it zone-by-zone over 35 metering zones then uses deductive programmed logic to try to prevent any of the highlights from blowing out. The "auto" sensor on the flash will also react to changes in overall reflectance of a scene but not to where in the frame the change is occurring. For example, you are shooting a table photo. People are standing behind the table covered with a white table cloth with an open space behind them. Evaluative flash metering will react to the fact there is a big white thing very close to the camera and reduce the amount of flash output to avoid overexposing it resulting in the people 4 feet further back being underexposed. Auto metering will see the same scene as an even balance of light and dark tones and give it more flash output. But since regardless of metering method the flash exposure is only correct at one distance if auto correctly exposes the faces it will blow out the detail in the table in the foreground. With ETTL an FEC adjustment can be used to expose the faces correctly but it will also blow out the detail in the foreground. This example reveals a fundamental difference between ambient and flash photography: distance to the flash matters when composing the photo.Regardless of how flash is metered and controlled only things at the same distance will be correctly exposed. Since digital requires exposing for the highlights the only way to ensure that no highlights in the photo are blown is to make sure what needs to be correctly exposed is closest to the flash and everything you want to be correctly exposed is the same distance from the flash. Not surprisingly if you start composing your flash shots with that in mind you will find that ETTL metering does a much better job of getting the exposure correct. If you see there is something reflective in the foreground which is unavoidable you can anticipate the ETTL metering will react to it and you will need to dial in more FEC than normal.Setting the CF.n for average flash metering in the camera works similar to auto in that it averages the overall scene, but the difference is that is averages what the camera sees, not what the flash see. The difference is significant if a zoom lens is used.One of the advantages of working with two flashes is that the distance of the key light which creates highlight exposure can be controlled separately from the camera distance. With ETTL metering the camera will automatically compensate for differences in distance of both key and fill on camera if either light moved. That is ideal for situations where the flash - subject difference can't be predicted or controlled.Its also worth noting that auto flash (sensor on flash) does not work with multiple flashes because the light from one flash will fool the other into thinking the scene is brighter than it actually is. That leaves manual power mode as the only option, which in turn means the exposure will only be correct at a specific distance. That works fine for static situations like portraits, but not well at all if the subject-flash distance is dynamic.When I used a pair of manual flashes it was with a simple distance differential technique. Both flashes were identical. If shooting at 8ft the off camera light would be placed at 6ft to get a one stop incident power differential and 3:1 lighting ratio. Finding the correct exposure was simply a matter of a one time test. Since the distance and power was the same the exposure at that distance combo was always the same also. If moving back to 11ft for a wider shot the off camera light moved to 8ft to maintain the ratio and the aperture was opened one stop. The technique was very simple but required shooting from pre-tested distances. In this photo of one of my early diffuser prototypes you can see the "cheat sheet" for manual flash. The flash in the photo is a 580ex but the exposure chart was for my Vivitar 285HVs.

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Note by © markle: well said Chuck but there is one more important aspect to consider: the fact that auto flashes give more predictable results, so the photographer can adjust knowing what is going to happen with no "surprises". Also any automatic flash (being e-ttl or thyristor) will try to compensate when there are other flashes illuminating the same scene . (obviously)

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Now It's up to us to decide which is better (for us): I'd rather have a thyristor flash giving predictable emissions rather than TTL flashes trying to make an interpretation where there is not much I can do about it.

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Of course if I shoot on the street and I have no time to think then I'll use some automatic flash praying for the best, but that's not the topic here (as I understand) because if I have time to set the shot then I wouldn't use any automatism (maybe the thyristors, but only those if I really have to) hehehehe

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But FEC on TTL flashes is (in my opinion) a contradiction in terms: mainly because it's a patch to compensate the "interpretation" pretty much unpredictable (from the start) and it may change once the scene is re-composed to apply the compensation. The FEL makes more sense but again is in contradiction with the "spirit" of the technology. In my opinion. Once again the thyristor system is hard to beat... hehehehe

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Automatic should be automatic: it's like you buy a car but the auto-transmission needs to be adjusted by you often: if I have to do that then why I bought an automatic car, plus if I have to switch to standard then the auto-transmission doesn't really work as it should because when you know that it changes the gears by itself then you don't expect to do it manually and then it does whatever the transmission likes anyway (after you manually adjust it) . I'm sorry but it doesn't work both ways: either you use an automatic flash or you don't. The auto-thyristors are now well proven, in automatic, indoor and outdoor. They are straight (with the instructions) consistent , honest, don't promise the moon and always do what they have to do, shot after shot, always the same.

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On the side of the topic I want to tell a real story happened few days ago: we were playing around with a couple of photographers waiting for a ceremony to start and we were discussing about fill flash , outdoor, sunny day. To cut the story short we made a test between my sunpak 383 and a nikon SB-800.I took one shot with the sunpak (1 stop difference from the ambient, F/11 auto set) and they took 8 shots with the SB-800 in aperture priority.The (one and only) shot from the sunpak was perfect and beautiful while the 8 shots with the Nikon were randomly over-exposed (all 8!)

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hmmm

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talking about fill flash outdoor and the limitation of the auto thyristor flashes.. hehehe

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sorry about the OT slip
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Note by © markle: cgardner said it all, correctly.

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I just wanted to add that the external metering of the 580EXII works with limitations with all the cameras before the 40D and mark IIIs and in automatic with the 40D and mark IIIs

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Basically with the 5D will underexpose 2 full stops and you have to enter the ISO manually. Plus you can't correct the under-exposure because the FEC won't work. The only thing you can do in order to get correct exposures is to cheat with the ISO (400 instead of 200 for example) but then it also depends on the distance and if you bounce the head or not.

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With a 1DIII you can (at least) set a permanent +2 FEC

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Just like the Metz 58 the auto thyristor sensor will suffer (being therefore inaccurate) at small apertures and with a subject close to the flash.

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for the rest it works pretty much like a Metz (again in AUTO mode or external metering like Canon likes to call it) but with the above limitations.

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Note by © cgardner: When I learned to use flash in the early 1970s it was with a single power Graflex flash with a head the size of a car headlight and 410V battery back that seemed as heavy as a car battery. There was only one option for exposure control: distance and aperture. Fortunately color negatives where more tolerant of over-exposure than digital so correct exposure was defined by making sure there was density in the shadows and letting the lab sort out the rest.

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I bought my first Vivitars, a pair of 263s, around 1975. I still have them and they still work. I initially thought the auto thyristor mode a great leap forward over manual, but found it was necessary to compensate with aperture when a scene was brighter or darker than normal. The fact I used two flashes most of the time in a key / fill arrangement also made it impossible to use auto mode in most situations and all things considered I found manual far more consistent and predictable and used it far more than auto mode.

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Prior to making the jump to the 20D I used a Minolta D7Hi which has a EVF and no x-sync limit which was a blessing for outdoor fill situations. By then I had upgraded to a pair of 285HV flashes which I used in manual mode. They were sufficient for most things, but to was real PITA to have spend thousands on a DSLR and fast glass only to be stuck shooting at f/11 because of the *&%$ x-sync limit. Thats really what motivated me to switch to the 580ex.

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My first reaction to ETTL flash exposure was that it sucked. Most shots were underexposed. With a bit of research and experimentation I figured out mastering ETTL flash was mostly a matter of understanding how the camera interpreted scenes. Results can get confusing because the 20D has 18 different ambient/flash metering combinations. Cameras with spot metering have 21. One winter day a few years ago I put the camera and flash on a tripod and shot wide, medium and close-up views of a complex indoor scene in all 18 modes using Av and ETTL with EC and FEC set at zero. The goal was to see how each combination handled the exposure differently. The results of the test are here: http://super.nova.org/DPR/Canon/TTL/ I concluded that none of the modes got the flash and ambient exposure perfect, but all things considered I thought the evaluative ambient + evaluative flash combination did the best overall job. I think that sticking with any combination of ambient and flash metering options will produce consistent results if used consistently enough to understand how the camera handles the more challenging flash metering situations such as brightly lit backlit subjects.

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That test confirmed the practicality of the workflow I'd been using. When confronted with a new scene I will most often put the camera in Av mode with evaluative metering and flash in ETTL with EC and FEC set to zero: the camera baseline. I lock AF with the * button then recompose and shoot. I evaluate the results then adjust EC and FEC as necessary to get to the correct exposure. I've done enough systematic testing to look at the scene and correlate the brightest thing in it to where the right edge of the histogram should be to reproduce it correctly. I've also learned to correlate the clipping warning in the playback to the point where texture starts to disappear in the highlights. When practical, such as with portraits, I use a white terry shop rag as an exposure guide, both visually and in conjunction with the clipping warning. It never takes more than a couple frames to zero in the exposure. For candid shooting I use ETTL and evaluative metering. I constantly monitor the playback and clipping warning as I shoot and correct FEC downward if the clipping warning occurs or raise it if a gap appears on the right of the histogram. Because of the way I evaluate and adjust there isn't much difference when I switch and shoot in M mode in static situations. I simply adjust flash power directly instead of playing the cat-and-mouse game with ETTL guessing and then overriding with FEC.

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Given the way I shoot and the fact I don't have a problem getting correct exposures consistently, there really wouldn't be any advantage to using auto mode vs either ETTL or M. As mentioned previously simply putting the flash metering in average mode would result in the camera doing the same type of broad average metering that the auto flash in the sensor does, and I can see no inherent advantage of having the flash sensor meter the exposure rather than the camera because what really matters is what the camera records, not what the flash sees.

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With regard to outdoor fill flash its important to realize that in most scenarios the sun is typically used as rim light and the flash as fill will not affect exposure of the highlights much. The shadow side of a head in the direct sun meters 3-stops below the sunny side. There is actually plenty of very soft fill light there created by the light bouncing off the sky, but the 3 -stop deferential puts in the face down in the middle of the camera sensor range making it very dark. Since fill is typically kept a stop below the ambient highlights on the hair and body when fill flash is added it only is lifting the soft sky fill about 2 stops there isn't as much risk variation in flash output fill blow the highlights as with indoor shooting.

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A mistake neophytes make with flash outdoors is shooting in Av mode and failing to heed the x-sync warning. In Av mode the camera automatically limits shutter speed to the x-sync speed. If aperture selection in sunlight is wider than f/11 the locking of the shutter at 1/200th or 1/250th may cause it to become overexposed. I've seen more than one person think overexposure in that situation was due to too much flash and not understand why a minus FEC adjustment had no effect. Using HS mode in Av is simpler because the flash which switch to HS mode whenever aperture selection and scene brightness push the shutter faster than x-sync. But regardless of flash mode I find it is less confusing and error-prone to shoot in M mode if the ambient light level is consistent. Starting with flash off and adjusting ambient exposure until there is no clipping provides a good baseline for evaluating the effect of the flash when it is added and will keep the background exposure consistent shot-to-shot as you reframe.

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I believe that the main point is this:

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" That test confirmed the practicality of the workflow I'd been using. When confronted with a new scene I will most often put the camera in Av mode with evaluative metering and flash in ETTL with EC and FEC set to zero: the camera baseline. I lock AF with the * button then recompose and shoot."

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The old ETTL used to compensate exposing correctly once you recompose and move the focus point .

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that was the key for success

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The new ETTLII performs some additional compensation resulting in erratic emissions. If you leave the AF with the shutter then it will try to "remember" where the focus was measuring in prevalence from there, even if you recompose moving the focus away.

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In any case having the AF with the "*" is another contraddiction in terms you are rejecting (or trying to) the entire ETTL philosophy doing that so basically another flash (metz or better a sunpak/vivitar 285HV) will make more sense. (in my opinion)

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There is no doubt that the most "consistent" flash will be in manual (the flash I mean).

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Bottom line ETTL has too much brain that I want to deal with. In the end we have two different practices: either you adjust your photography trying to anticipate or predict the flash system or you use the most predictable automatic system you can find and make the flash adjusting itself to your photography. because we're talking about portable flashes, not studio or location setups.

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I gave up on ETTL I&II because I was tired of chasing the "moods" of whoever wrote the software for it.

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Because at the end of the day what really counts are the pictures and if I have to concentrate anticipating or trying to predict a flash system then I'll be losing too many shots.... hehehehe

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Note by © cgardner: Markle, NK Guy's site explains the differences between E-TTL and E-TTL II. http://www.photonotes.org/articles/eos-flash/#ettl

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At the default settings both E-TTL and E-TTL II meter ambient AE when the shutter is half-pressed and fire and measure pre-flash when the shutter is fully-pressed. The primary differences is are that E-TTL uses the active AF point for exposure weighting and has the auto-fill reduction function, while E-TTL II bases its flash weighing on algorithms based on zone-by-zone comparison of ambient and pre-flash and focus distance information if available. E-TTL II also has the ability to detect and eliminate exposure errors cause by direct specular reflections of the flash, such as when there is a mirror in the background -- try that with your auto thyristor flash

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Composition habits and camera CF.n settings will affect metering. With ETTL-II when CF.n 04 is set to 0 if I point the camera at a dark area in Av mode and half-press the shutter, then recompose to a lighter area the ambient shutter time will be incorrectly based on the darker area I locked AE on with the half press, but flash will be based on the area being photographed, resulting in gross over-exposure. Setting CF.n 4 to 1 separates the AE and AF independently, shifting the AF lock to the * button, allowing me to press * to lock AF, recompose, then half press the shutter to lock ambient AE. The pre-flash and flash metering doesn't occur until after the shutter is fully pressed but if I don't change the framing between the time I half-press and fully press the shutter both ambient and flash metering are based on the final photo composition. Most significantly with E-TTL II the recomposition after AF lock does not affect exposure as it did with the AF-point-weighted E-TTL system.

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My day job for the past 30 or so years has involved designing and programming database information systems so perhaps I have a better understanding and more patience for the "moods" (logic) of the software than you do. I concluded that the best approach not to even try to out guess ETTL-II in advance, or expect the camera to get the exposure correct all the time. I do the opposite: I first let the camera take its best shot at getting the exposure correct before trying to second-guess it. I eliminate variables in the workflow by always using the same metering mode and taking initial test shots from a consistent baseline of EC = 0 and FEC= 0 rather than whatever the camera was set at previously. Only after I evaluate the results of default metering setting of the camera is do I intervene and override it with EC or FEC. Working with E-TTL II systematically from a consistent baseline is what has helped me understand how to make it work effectively.

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Note by © markle: Yes but come on there is always some new "excuse" for E-TTL to illuminate is some strange manner. Now is the focus area too bright, now is the camera position too high, now is some CF on both the flash and the camera, now is because the ambient was too bright, now is because I supposed to lock fel fec adjust re-measure, compose and don't shoot, re-compose and shoot.

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Can I tell you what I do on weddings?

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- I bring two sunpak 383 and a tinycycler

- I set the camera in manual f/5.6

- I check the flash settings (ISO 200 , F/5.6 in auto)

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and that's it

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no.. seriously.. that's it

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thanks for the link, it was interesting but like I said the system shows too much brain.

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P.S. : not to be redundant but I see that e-ttl works only when the subject is tight up, close ups for example, not too much graduations of colors or luminosity: then it gets it right (maybe). But in similar conditions the sunpak/vivitar flashes in auto ALSO get it right. but all the time. not just most of the time.

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to continue.....