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10-02-2009, 07:49 PM   #1
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Join Date: Feb 2009
Location: Dayton Ohio
Posts: 132
Quick Question.. Please Help? K20D Focus Sensor size?

I have a K20D, been shooting with it a lot. I am curious if someone could point me in direction of something that shows the relative size of the K20D focus sensors compared to the actual outline of them in the viewfinder.

Any help here? Thanks!

10-02-2009, 09:04 PM   #2

Join Date: Oct 2006
Location: Chicago suburb, IL, USA
Posts: 1,535
hi designinme,

The AF sensor indicators (the red squares and lines that light up) only show the relative locations of the sensors in the viewfinder. The actual sensor area is roughly the size of the central circular area on the grid on the stock focusing screen.

You can test this by facing a featureless wall near a corner of the room making sure that you're farther from the wall than the minimum focusing distance of your lens. With your lens defocused, actuate the AF. It will probably hunt full lock to lock and won't not lock focus, giving you a blinking green hexagon in the viewfinder. Move the camera so the central circular area of the grid approaches the corner of the room, reactuating the AF as you go. The AF will first lock on the corner of the room when the contrast line of the corner starts to enter the central area of the grid.

You can more precisely locate the edges of the sensor's area by using a sharper line, and by being more precise while moving the camera, but you get the idea. You can also repeat this while selecting one of the other focus points to determine their areas if you want to.

10-02-2009, 09:31 PM   #3
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Join Date: Feb 2009
Location: Dayton Ohio
Posts: 132
Original Poster
Yeah, I have no idea why I didn't think of that! Thanks for the quick and easy solution to figuring that out. I was just playing around, and from what I am finding... it looks like the center point is by far the largest to object around or near it... with the points points right or left ( but not extreme right or left ) to be smaller and more precise. Interesting.

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