PAW 14

When I first began my Picture a Week project, one of my ideas was that the picture would tell a story, be complete in itself, etc.  I did not intend to fully document the details of the picture, equipment or technique.  Of course, I can hardly help doing just that!

From time to time I like to take on the challenge of making a self portrait and this week’s PAW is my latest effort.  It represents quite a bit of effort.  First, I wanted a self portrait that showed me doing something and not just a head shot.  So, what do I do?  You see me at one of my major activities.  I decided to use the computer screens as the light source; this both to provide a different look and also to minimize my cleanup efforts.  A piece of black art board was placed behind the laptop to further hide my junk.  My Canon 7D with 15-85mm lens was placed on a tripod to be triggered by the Yongnuo RF-602 wireless remote.  A little rearranging, a few trial shots to set exposure and the rest was up to the model. 

7D Hannah

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Having previous posted a series on portraits and depth of field based on my G9, I decided to repeat one shot using the 7D. Fortunately, Hannah was still available. The 7D was fitted with a Canon 85mm f1.8 and set in Av mode for f1.8 at ISO 100. The setup and distances were roughly the same as previously posted with the G9.



It was a nice clear day outside and even at ISO 100, the shutter speed was 1/8000 second! Incredible as this seems, it actually is almost exactly the “Sunny Sixteen” exposure albeit shifted quite a bit. The combination of sunlight and concrete made for very harsh lighting and I give full credit to Hannah for not squinting. But, getting back to the point, notice the blurred background. In fact, notice the slight blur of the front tire!

With the setup and a patience model, I just had to try a few shots using the 7D as a trigger for a 580EX flash outdoors. The 7D flash system is very intriguing and I’ll be learning more about it. In fact, I learned something today.

I first attempted to place the 580EX slightly behind Hannah to provide a bit of back lighting and separation from the background. The 580EX simply would not flash. Hand-holding the 7D, I was about 20 feet away. It turns out that you have to remember to turn it on! But even then it would not fire until the 7D was about 4 feet away. I could see the red light blinking on the 580EX but finally realized that the 580EX was seeing a tiny little pop-up flash and a huge bright sun. With the 580EX facing away from the sun, the 7D will easily trigger it from 20 feet away. Lesson learned.

Taking another approach to lighting Hannah, I decided to underexpose the background and use the 580EX to light Hannah from camera right. Accomplishing this was made complicated because the sync speed of the 7D is limited to 1/250 second and at 1/250 second, the ambient exposure was f11. Giving it a try, I switched to manual mode and set 1/250 second and f22 – about two stops underexposed for the background. The 7D flash system was set to an 8:1 ratio for the external flash. The result – first attempt! – is below.

Not too bad for a first try and definitely better than most of my first guesses with fully manual exposure and manual flash.

I like the ability to blur the background and the opportunity to use my 85mm lens with the 7D. As a flash trigger, the 7D seems OK outdoors with a range of 20 to 25 feet provided the auxiliary flash can see the 7D without also seeing the sun.

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G9: Blurring the background

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A blurred background is useful for isolating and emphasizing the main subject. Extremely blurred backgrounds add a particularly nice effect to portraits. Unfortunately, extreme background blur is not easily obtained using short focal length lenses such as are used with the Canon G series and most other small sensor digital cameras.

The concept for producing a blurred background is simple: use a combination of focal length, aperture and distance such that the background is outside the depth of field. In practice, this means selecting a telephoto lens with a large aperture, placing the camera near the subject and placing the subject away from the background. With the G9, this means zooming the lens to near maximum, forcing the largest possible aperture and placing the subject far from the background.

A previous posting showed how the depth of field varied with the focal length of the G9 at “portrait” distances. Another post showed the maximum aperture for those focal lengths. These two posts illustrate the relationships between zoom (focal length), shooting distance and aperture for the G9.

For this picture of Hannah, I used the G9 at maximum zoom, f4.8 and was about 12 feet from her. The shrubbery was another 12 feet away; the fence (barely discernable) was about 30 feet behind Hannah. These are fairly generous distances; in fact, more separation than is often available. Even so, the background behind Hannah is not particularly blurred (click for a larger image).

Depth-of-field calculations are based on small but noticeable blurs at certain enlargements and viewing distances. For more information, visit and study at DOFMaster. In contrast, the background blur that many photographers want for portraiture is extreme. My own personal favorite is of Wallace; however, it was not made with the G9.

Small sensor cameras like the G9 are great when the goal is to have nearly everything in focus but such cameras are just not the right tool for producing extreme background blur for ‘portrait’ photography.
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G9: Portrait Distance

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It seems to me that actual height for a tightly composed head shot is about two feet. How far away from the subject should the camera be to capture this two foot high subject? I suppose the distance can be calculated but frankly it is just easier to tape a yardstick to the wall and take a few shots.

For my G9, these are the camera-to-subject distances for various focal lengths.





The focal lengths in the chart are the same as the focal lengths from the previous posting which gave the maximum aperture for various focal lengths.

The depth of field can be calculated from distance, focal length and aperture. Taking some liberties in rounding off, depth of field for a portrait setting with the G9 is about one foot – give or take a few inches.

This little experiment would seem to indicate that a blurred background would be easily obtained with the Canon G9; however, the opposite is true. In fact, blurred backgrounds are difficult to obtain and extreme blur for portraits and larger scenes is nearly impossible to achieve with the G9. The apparent discrepancy is because the depth of field calculation is intended to predict the onset of blur and not the extreme.

Next: an example of typical G9 background blur for portrait setting
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G9: Focus Vertically or Horizontally?

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Although I’ve made several postings about focusing the G9 (sort of cross referenced here), a few days ago I began to think that my G9 was focusing much better when held horizontally (landscape) than when held vertically (portrait). In fact, sometimes it would not focus when turned vertically. Was my G9 broken?

On further review, I’ve come to realize that the small Flexizone frame works best on vertical lines when held horizontally and on horizontal lines when held vertically. Said another way, when shooting in landscape orientation (the “normal” shot), look for a vertical line on which to focus. When shooting a portrait, look for a horizontal line and focus on it.

My problem – when I feared my G9 was broken – was that I was shooting in portrait orientation and the subject lines were vertical. The G9 just would not focus on those vertical lines with the small Flexizone frame. But turning the camera to landscape orientation, it focused immediately.

In much the same way, when using the small Flexizone frame, the G9 struggles to focus on simple horizontal lines when the camera is in landscape orientation. Turned vertically, focusing is routine on those same horizontal lines.

The AiAF matrix of focus points does not have this problem – probably because one of the focus points usually finds an appropriate contrast pattern.

I still prefer the small Flexizone frame but now have a better understanding of those missed focuses. Strange, but true.
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