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Old Aug 19, 2007, 6:09 PM   #11
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1eyedeer wrote:
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I understand theadvantage of multiple focus points for tracking rapidly moving objects, e.g., sports action and birds in flight.
It has advantage in composition of other types of photography as well - i.e. choosing the focus point over your subject and not doing a focus and recompose. If you get into shallow-DOF photos at all where you only have inches of DOF - focus and recompose leads to out of focus shots.

Now - when you get into the realm of 45 points - now you have MULTIPLE points on your subject - so the camera gets an even better idea of how to focus - if you have 7-8 points on your subject you have a better chance of the camera detecting the necessary contrast to achieve the sharpest focus - without hunting with a single point to find good enough contrast.
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Old Aug 19, 2007, 6:48 PM   #12
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In as much as I got the feeling that the camera price point was indeed an issue within dmx's post. I felt safe in suggesting the Nikon D-40 (which now has more than 40 different lenses available for it) and the Pentax K-100D as a good starting point in his or her quest to increase their photographic skills.

If the forward progress in increasing theirskill level goes as projected, they could then use their existing lenses to move upward to more feature rich DSLR cameras. The most important issue was to get the learning curve moving forward.

Everyone of us had to begin our photo careers with lesser feature laden cameras than we are using today. And that is what learning and moving upwards in our photo skills is all about. So I went for an answer to get dmx started, rather than going for and answer that while 100% technically correct, might have priced dmx out of the DSLR camera market.Icreated a subjectivesort of answer, hoping to create an easier financialpathway to get dmxstarted.

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Old Aug 20, 2007, 2:47 AM   #13
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JohnG wrote:

"Now - when you get into the realm of 45 points - now you have MULTIPLE points on your subject - so the camera gets an even better idea of how to focus - if you have 7-8 points on your subject you have a better chance of the camera detecting the necessary contrast to achieve the sharpest focus - without hunting with a single point to find good enough contrast."

Having been curious about a camera having a mind boggling 45 points, I found out that a Canon 1D has 45 points. !9 of these are described as high sensitivity and 26 for tracking presumably once one of the 19 has detected a suitable subject. This helps answer my previous question concerning what is the desired minimum number of points forrapidly moving subjects. In general on DSLR cameras, do all the focusing points have the same sensitivity, or is the central point the most sensitive?

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Old Aug 20, 2007, 7:19 AM   #14
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1eyedeer wrote:
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In general on DSLR cameras, do all the focusing points have the same sensitivity, or is the central point the most sensitive?
It varies by camera. In some cameras the center point is no more sensitive than the others. In other models the center point is a cross type sensor - meaning it can detect contrast change along both vertical and horizontal axis. In some cameras the center point is more sensitive when using f2.8 lenses, in others that sensitivity extends to 4.0 or 5.6 lenses. For example, the new Canon 40d hasall nine focus points as cross type sensors.
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Old Aug 20, 2007, 11:57 AM   #15
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Thanks for the information JohnG. If in the future, I need multiple focus points, I know a little more of what to look for. I noticed that on the Canon10D, only the central point had the low aperture sensitivity, whilst you say that the 40D has all 9 focal points all with the same sensitivity - shows how the camera body development progresses.
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