G9: Focusing Indoors

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As previously noted, although the G9 has five automatic focusing modes, I almost always choose the small Flexizone frame centered in the LCD. I place the focus frame on the subject of interest, push the shutter button halfway, think “focus”, check for the frame to turn green, recompose the scene and finish pressing the shutter. To get additional shots from the same vantage point, I then switch to manual focus and keep the previous focus distance. This method almost always works well even if it is a bit slow and methodical.

Without recomposing, the small Flexizone frame may not detect enough contrast to obtain focus. Also, without recomposing, the small Flexizone frame may focus on the wrong object. This is particularly a problem when photographing indoors. To illustrate this problem, I set up my G9 on a tripod and tried the various focusing methods indoors.

In this scene, the G9 was set for the widest angle, 7.4mm; the aperture was f4.5 (the “Sweet Aperture”) . The image shown was downsized from the in-camera JPEG. The focus distance, as determined by the small Flexizone frame was 15 feet but the large Flexizone frame determined the focus to be 8 feet! This discrepancy occurred because the small frame fell on a photo on the opposite wall but the large frame included a chair. The focus distance, as determined by the small AiAF matrix was 12 feet. The large AiAF matrix also determined the focus to be 12 feet. Interestingly, the large AiAF matrix did not always lock onto the same object even though the G9 was on a tripod. I had suspected that the different focus methods would lock onto different objects and I was correct.

Using manual focus, I dialed in 5 feet and took another shot. Later, to my surprise, all the pictures look essentially the same. Why? Of course, the explanation is hyperfocal distance. For the 7.4mm zoom focal length and f4.5 aperture, everything from about 4 feet to infinity is in acceptable focus. In setting up my test, I’d forgotten about the hyperfocal distance. Chalk one up for the G9.

Since this humbling experience, I’ve toyed with the various focus modes quite a bit. My basic hypothesis was correct: With any focus mode other than the small Flexizone frame, I cannot be certain of getting the exact focus point that I want. Fortunately, often it just doesn’t matter.

But sometimes it does .... (more later)
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G9: Can’t Focus

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Sometimes the G9 can’t focus. When the G9 has acquired focus, it beeps twice (very quickly) and the AF frame on the LCD turns green. If the G9 is confused about the focus, it only beeps once and the AF frame turns yellow. That (yellow frame) was the case for this uncropped image. For this composition – as attractive as it is – the small AF frame did not include any details and the G9 could not focus. I pressed the shutter button anyway and got an out-of-focus picture.

Switching to manual focus immediately after the shot, I found that the G9 decided to focus at infinity instead of the true distance of about nine feet. Had I selected the nine large frame AiAF focus method, the G9 would have focused correctly because some of the frames would have included the plaques (tested and proven).

As noted previously, I almost always use the small Flexizone frame for focusing. I even leave the frame centered; that is, I focus, recompose and shoot. But sometimes, especially when in a hurry, this is not the best method and it definitely is not the best method without recomposing.

The G9 focuses by means of contrast detection and tends to select the closest object. When using the small AF frame to focus, make certain that the focus frame includes an edge, some sort of pattern, different colors, different lighting, etc. In fact, when using the large frame or the multiple AiAF frames, keep in mind that the focus point will be selected on the basis of proximity and contrast.

And watch for that frame to turn green!

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