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Products >> All Products In Focus: The Basics of External Flash Photography- Part2

Speedlite 470EX-AI: Exploring the World’s First AI Bounce Function

Announced by Canon on 26 February 2018, the Speedlite 470EX-AI is the world’s first Speedlite equipped with an Auto Intelligent (AI) bounce function. Capable of automatically analysing and setting the optimal bounce angle, it promises to aid and enhance the bounce flash photography experience for both flash photography beginner and experienced users. In this article, find out about shooting techniques that utilise the AI.B full-auto and AI.B semi-auto modes. (Reported by: Seigi Takakuwa / Model: Hitomi Ozawa (Oscar Promotion))

Speedlite 470EX-AI


AI Bounce: Bounce flash photography made easier

Canon's new Speedlite 470EX-AI is equipped with a ground-breaking system not seen in previous models.

When a conventional clip-on flash is used for bounce flash photography, the camera sets the optimal flash output using the Evaluative Through The Lens (E-TTL) system. The optimal bounce angle must be set manually, taking into account the distance of the flash from the subject and the height of the ceiling.

However, on the Speedlite 470EX-AI, this entire process is automated by the Auto Intelligent (AI) Bounce function. This function is driven by the combination of a built-in CPU, acceleration detection sensor, distance measurement sensor, and motor for bounce flash photography, which work together to find and set the optimal flash output and bounce angle. These features might well give a hint of what to expect on the flash units of the future.


The two different modes of AI Bounce

The AI Bounce function has two automatic modes.

In AI.B full-auto mode, the camera controls the settings for bounce flash photography, making it a breeze to use even for new users. The light emitted from the flash is just enough to illuminate the subject beautifully even after being bounced and diffused, resulting in natural-looking photos without harsh shadows in the background.

In AI.B semi-auto mode, the Speedlite can be set to “memorise” a bounce angle and flash orientation that is manually pre-set by the user. If the user moves the camera from vertical to horizontal orientation or vice versa, the Speedlite will automatically adjust the bounce angle and orientation so that the angle to the flash surface is the same as the stored setting. Users are able to carry out their shoot seamlessly, without having to make constant manual adjustments to the bounce angle.

A handy tip to remember: AI.B full-auto mode makes it easy to perform a ceiling bounce, while AI.B semi-auto mode allows easy wall bounce.

In this article, we test the Speedlite 470EX-AI at different focal lengths, shooting distances and camera orientations. This not only lets us see for ourselves how the AI Bounce function operates, but also allows us to verify how effectively it illuminates the subject. Following that, I will share some techniques that you can use with each mode.

Using ceiling bounce for fill lighting

EOS 5D Mark IV/ EF24-70mm f/2.8L II USM/ FL: 44mm/ Manual exposure (f/2.8, 1/200 sec)/ ISO 100/ WB: Auto

While I tried to make the most of the natural light that entered through the window, the scene was slightly backlit, making the model’s face appear darker. To create fill lighting, I used the AI.B full-auto mode on the Speedlite 470EX-AI to perform a ceiling bounce. This resulted in the natural-looking image you see here.


Testing out the AI Bounce function: How does flash head movement and exposure change?

Do the focal length, portrait/landscape orientation, shooting distance, and background distance affect the AI Bounce function and the effects it achieves? To find out, I decided to put the AI Bounce function through its paces.

Test 1: Changing the focal length while in AI.B full-auto mode

Underlying concept
In conventional flash photography, the optimum angle of coverage (flash angle/flash coverage) depends on the focal length (angle-of-view).
The narrower the flash angle, the further it can reach. 
When shooting wide angle, the flash coverage has to be wide enough to cover the entire angle-of view. When shooting telephoto, the flash coverage has to reach the subject.

How does this concept affect bounce flash and the AI.B full-auto function? In Test 1, we shoot with different focal lengths and observe the results. 

Shooting conditions

Mode: AI.B full-auto mode

What was fixed:
- The position of the subject
- The distance between the subject and the background
- The distance from the camera to the ceiling
- The camera settings.

What was changed:
- The focal length (1 image shot at 24mm wide-angle end; another shot at 200mm telephoto end)
- The shooting position, to keep the composition as consistent as possible for easier comparing
(Note: While the subject remains the same size in both images, the respective wide-angle lens characteristics and telephoto lens characteristics result in a different angle-of-view, as you can tell from the background.)


Results and explanation

To keep the composition consistent, it was necessary to change the distance of the camera from the subject (i.e., the camera position) for each focal length. As a result, the distance between the camera and the background also changed. However, unlike in Test 3, the distance between the subject and the background stays the same. 
It is also worth noting that in AI.B full-auto mode, the flash angle is fixed at 50mm. How well the entire scene is illuminated depends solely on how well the bounce angle is calibrated. 

The 24mm focal length (wide-angle) example:  At such a short subject-flash distance, it is easy to set a bounce angle where the light that bounces off the surface would be too strong, overexposing the image.
However, AI.B full-auto set a flash head angle that fired the flash toward the ceiling at an angle behind the photographer. This seems to have diffused the light enough to ensure that just the right amount of light reached the subject and background.
There are some shadows cast on the front of the subject. These are the outcome of the angle at which the light bounced off the ceiling. They give the image more dimension.

The 200mm focal length (telephoto) example:  Despite the 6m distance between the flash and the subject, the bounce angle set by AI.B has also ensured that the subject and background were well-lit, and the lighting was soft and uniform. 

 The bounce angle set by AI.B full-auto resulted in natural and even lighting on the subject and background for both images. Although the final images look different, they are the natural outcome of the light bouncing off the ceiling at different angles. When shooting from a short distance such as in the 24mm example, to achieve the same lighting effect as the 200mm example, you would have to use a bounce adapter to further diffuse the light. (See Tip 4 of 5 Simple Bounce Flash Photography Tips)


24mm lens, shooting distance 0.9m

Shorter shooting distance, stronger shadows

The shadows in front appear a little stronger, which gives the subject more dimension.

200mm lens, shooting distance 6m

Larger shooting distance, softer and more even lighting

Light strikes the subject evenly, resulting in a softer effect compared to the 24mm example.

Lighting setup diagram (short shooting distance)

A: Flash head orientation
B: Shooting distance (0.9m)

Lighting setup diagram (long shooting distance

A: Flash head orientation
B: Shooting distance (6m)


Test 2: Changing to the portrait/landscape orientation while in AI.B semi-auto mode

Underlying concept

AI.B semi-auto mode can be set to memorize a preset bounce angle. When you change the camera position such as by changing its orientation, the flash head orientation needs to change to ensure the same bounce angle as before.

Test 2 aims to verify the reaction of the Speedlite 470EX-AI  in this mode and the results achieved.

Shooting conditions

Mode: AI.B semi-auto mode, using a pre-set bounce angle for wall-bounce

What was fixed:
- The distance from the camera to the subject
- The position of the subject

What was changed:
The camera orientation

Other details:
The shoot location was a home studio, which had natural light entering from two sides. The subject was positioned so that she could be illuminated by the natural light from both sides.


Results and explanation

In both the portrait and landscape orientations, the angle was set automatically. The wall bounce diffused the light from the flash and provided a more natural lighting, allowing the shot to be taken at a natural brightness. There was not much visible difference in lighting between both shots.

Because the flash was mounted onto the camera, the position of the flash head changed when the camera orientation was changed. However, in terms of the shooting result, the difference was marginal.


Shot in landscape orientation

Shot in landscape orientation, Landscape camera orientation

A: Flash orientation


Shot in portrait orientation

Shot in portrait orientation, Portrait orientation

A: Flash head orientation


Test 3: Changing the shooting distance and background distance in AI.B full-auto mode

Underlying concept

In AI.B full-auto mode, the flash-subject distance is taken into account when the flash determines the optimal bounce angle. Test 3 aims to verify the function's performance when the subject-flash distance changes.

Shooting conditions

Mode: AI.B full-auto mode

What was fixed:
- The camera position
- The camera settings
- The focal length

What was changed:
- The distance of the subject  from the camera
- The distance between the subject and the background

Other details:
-4 shots were taken with the subject moving toward the camera.


Results and explanation

The impact of the natural light from the side resulted in a difference in brightness of the background. However, the optimal settings were applied at each of the shooting distances, and the shots were taken with diffused light that illuminated the main subject beautifully.

As the Speedlite sets the flash output and bounce angle based on the distance from the subject, each time, the output and bounce angle were just enough to ensure that the model was sufficiently lit. This meant that as the model moved closer to the camera and further from the background, the background became progressively darker as less light reached it. 

Full body shot (Shooting distance: 6m; Background distance: 0m): The light was diffused evenly so that the entire background was lit up, creating a photo that appeared bright throughout. 
3/4 shot (Shooting distance: 3.5m; Background distance: 2m): The background became a little darker, which gave the photo depth.  
Waist-up shot (Shooting distance 2m, background distance 3.5m): The blurred background appeared even darker, which made the subject stand out. AI.B full-auto set a flash-head orientation that fired behind the photographer. 
Chest-up shot (Shooting distance 1m, background distance 4.5m): Same as for the waist-up shot. 

As with Test 1, at a certain point, the AI.B full-auto mode starts to angle the flash head so that the flash bounces off from a point in the ceiling behind the photographer. This makes the light travel a longer distance before and after a bounce, ensuring that it is sufficiently diffused by the time it hits the subject.

In each photo, the colours produced were more beautiful and the skin tone appeared more appealing than when only natural light was used. The flash light and natural light work well together, so you can make the most of that in a variety of scenes.


Shooting distance: 6m

Shooting distance 6m
Shooting distance 6m lighting setup

A: Flash head orientation
B: Shooting distance (6m)


Shooting distance 3.5m, background distance 2m

Shooting distance 3.5m
Shooting distance 3.5m lighting setup

A: Flash head orientation
B: Shooting distance (3.5m)
C: Background distance (2m)


Shooting distance 2m, background distance 3.5m

Shooting distance 2m
Shooting distance 2m lighting setup

A: Flash head orientation
B: Shooting distance (2m)
C: Background distance (3.5m)


Shooting distance 1m, background distance 4.5m

Shooting distance 1m
Shooting distance 1m lighting setup

A: Flash head orientation
B: Shooting distance (1m)
C: Background distance (4.5m)


Shooting Techniques

1. AI.B full-auto mode: Using ceiling bounce to create a fill light similar to that from a reflector

AI.B full-auto mode example (ceiling bounce fill)

EOS 5D Mark IV/ EF85mm f/1.8 USM/ Manual exposure/ WB: Auto

Flash mode: E-TTL/ Flash compensation: EV-0.7/ Flash angle: 85mm
Focal length: 85mm/ Shutter speed: 1/400 sec/ Aperture: f/1.8/ ISO speed: 100


I made use of the beautiful light streaming in onto the sofa to capture the soft and mellow atmosphere of the model relaxing by the window. If I used only natural light, the model's face would appear dark due to the backlighting. I could adjust the exposure to ensure that the face is well-lit, but I would also lose the unique atmosphere created by the gentle and natural window light.

The best solution, therefore, was to keep the overall contrast while ensuring that the face was lit up in a way that looked natural. To achieve that, I set the E-TTL flash compensation to EV -0.7 in AI.B full-auto mode, and used ceiling bounce to produce a soft fill light that matched the ambient light.

By using high-speed sync with a shutter speed of at least 1/200 sec, I was able to shoot at maximum aperture without changing the depth-of-field. With this, I adjusted how the subject was lit up by both the light and the flash light, which gently softened the shadows. While I did use a reflector in my setup, it was solely for the purpose of creating catchlights—the angle of the light reflected from it was not suitable for illuminating the subject's face.


Speedlite not used

No Speedlite used

Without a fill light, the subject’s face appears dark.


The setup

AI.B full-auto mode example setup

Beautiful light shone in through the window. A reflector board was placed below to create catchlights.

1: Direction of the sunlight
2: Ceiling bounce
3: Strikes the white reflector board (creates catchlights, light insufficient to light the face)


Shooting procedure

AI.B full-auto mode shoot procedure 1

1: For the flash mode, select "E-TTL", and set the flash exposure compensation to "-0.7EV". The key is to set a weak flash so as to produce a natural ambience.


AI.B full-auto mode shoot procedure 2

2: Slide the AI.B toggle switch to "F". Half-press the shutter button to automatically return the bounce angle to 0°.


AI.B full-auto mode shoot procedure 3

3: After deciding on the composition and shooting angle, press the AI.B button. This measures the distance to the subject and the distance to the ceiling for bouncing the flash light. A pre-flash will be fired.

If you change the camera position, half-press the shutter button twice in succession. This will move the flash head and automatically correct the bounce angle to the same as before you moved the camera.

You might also be interested in these indoor portraiture tips and tutorials:
Step by Step: How to Capture Dramatic Portraits Using Backlight from the Window
Aperture-Priority AE Technique #4: Photographing Facial Expressions


2. AI.B semi-auto mode: Using wall bounce to create a fill light from the side

AI.B semi-auto mode example (wall bounce fill from side)

EOS 5D Mark IV/ EF24-70mm f/2.8L II USM/ Manual exposure/ WB: Auto

Flash mode: E-TTL/ Flash compensation: EV±0/ Flash angle: 80mm
Focal length: 70mm/ Shutter speed: 1/80 sec/ Aperture: f/2.8/ ISO speed: 100


The shot uses the natural light pouring in from the background to create the sheen in the model's hair. However, using this light alone would result in shadows on the face. The way the shadows were cast also made the colour of the skirt look duller.

I therefore used AI.B semi-auto mode to create a fill light that supplemented the natural light. This was done by placing a large reflector board on the wall and bouncing light off it. Diffused by the bouncing, the light was reflected onto the front of the subject. This lifts (brightens) the shadows and makes the colours in this photo look more intense.

When AI.B semi-auto mode is used, you can set the Speedlite to store a bounce angle that you have pre-determined. Once that has been done, even if you change the orientation of the camera, the orientation of the flash head will be automatically adjusted and corrected to produce the memorised bounce angle. This lets you shoot seamlessly and efficiently with the optimal bounce angle without missing a beat, regardless of how you decide to hold the camera.


Speedlite not used

No Speedlite used

With natural light alone, there are stronger shadows on the subject’s face, and part of her skirt.


The setup

A large reflector board was placed on the wall to the left so the light that bounced off the board would illuminate the model, who was standing about 2 metres away.

AI.B semi-auto mode example (setup)

A wall bounce was performed by directing the flash head toward the white reflector board.


Shooting procedure

AI.B semi-auto mode step 1

1: For the flash mode, select "E-TTL". Take some test shots without using flash exposure compensation at first, and then adjust the exposure compensation as needed to achieve the desired brightness.


AI.B semi-auto mode step 2

2: Slide the AI.B toggle switch to "S". Half-press the shutter button to automatically set the bounce angle to the 0° position.


AI.B semi-auto mode step 3

3: Once you have decided on the bounce angle, press the ANGLE SET button. This registers (stores) the bounce angle.

When you change the orientation of the camera and need to recall the same bounce angle, press the AI.B button and then half-press the shutter twice in succession. The flash head will move and reset to provide the stored bounce angle.


Thinking of buying the Speedlite 470EX-AI? These articles might help you make your decision:
Choosing an External Flash (1): Flash Power
Choosing an External Flash (2): What Else Can A Flash Do?

For more tips and tutorials on external flash photography, check out:
In Focus: The Basics of External Flash Photography

What other equipment do you need for indoor portrait photography? Check out the following lenses that portrait photographers love:
EF85mm f/1.4L IS USM Review: An Excellent Portrait Lens for Handheld Shooting
Why the EF85mm f/1.8 USM is Ideal for Portrait Photography


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Seigi Takakuwa

Seigi Takakuwa

Seigi Takakuwa’s first job was with a publisher, where he first worked as a photographer’s assistant before breaking off on his own to become a freelance photographer. He currently shoots mainly for beauty and fashion advertisements, magazines and catalogues. He is well-acclaimed in the industry for the quality of his entire workflow, from photography all the way to retouching, and has earned accolades especially for beauty photography. In 2012 and 2013, he achieved Honorable Mentions in the Professional- Advertising: Beauty category of the prestigious International Photography Awards.

Website: https://www.seigi-photograph.com/