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06-19-2009, 05:33 AM   #1
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K20D Question on focus and shake

I just received my first DSLR, a K20D, after 50 years of film. While involved most of the manual is pretty straight forward but lacking a bit in background hence I have a few questions (for now):

1. It recommends using AF-S but I don't see why AF-C would not be just as good and more versatile. Is it damaging to the camera to leave it in AF-C? If shooting fast moving action with continuous shooting, i.e., 3 fps, should use AF-C or AF-S?

2. I would have thought that one would leave the anti-shake function on all the time but the manual recommends it only for low shutter speed relative to focal length. What's the harm in leaving it on and why do they insist on it being off if using a tripod? Also, as above, for continuous shooting should it be on or off?

If the answers relate simply to photo quality I'll soon figure it out but I don't want to do anything damaging to the camera.



06-19-2009, 07:52 AM   #2
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With AF-S the camera is assuming everything is relatively static. When it finds what it thinks is the focus it will stop and let the shutter open if you have the button down. This will usually give you a photo that is in best focus. If the frame is relatively static this is usually best. When you use AF-C the camera assumes things are moving. It will continuously look to change the focus. The slightest change of camera may send the camera out of focus as it looks for a new focus. If things are changing this is good as the camera will get it back faster (probably) then you can do it thus getting more in focus shots. If something is not moving then the camera with AF-C will let you take the shot when things are not in focus. Sometimes the camera will want to focus on things that are not what you, the photographer, do not want in focus. Then you may have to either manually choose the focal point or use manual focus. The idea is to give you, the photographer, the control/best tool for the job.

SR is a little like AF-C in that the camera is always looking for movement. Both of these are a kind of system noise not to be confused with the noise in the photo. With the SR used now it may not see that there is no movement and move the sensor a little anyway. If you are on a tripod the SR may add a little movement thus blurring the photo. SR helps the most at slower shutter speeds hand held. At higher speeds it doesnít help but it doesnít hurt ether. On a tripod it may hurt so it is recommended to turn SR off. When you use 2 second mirror up the camera is assuming it is on a tripod so it turns off SR.

Leaving ether SR or AF-C wonít really hurt the camera (any more then just using the camera will ware it out but if you donít use it why get it) as other thing will most likely go out before these will. But like any setting on the camera it may effect the photo you take.

06-19-2009, 09:08 PM   #3
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As for the SR, be sure to get the firmware update to version 1.03, if you haven't already, it is a goodness, particularly about instances of undesireable sensor movement that DAZ described.
06-19-2009, 09:15 PM   #4
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Also, when in AF-S the camera will not let you release the shutter until it thinks it has locked focus. So you can hold down the shutter button all the way and if it is still hunting then it wont take a picture. For AF-C the camera will release the shutter as soon as you press down the shutter button all the way regardless of whether focus has been acheived or not. Personally I like to use AF-S because I know my subject will be in focus when I take the shot. If youre in AF-C you may take the picture too quickly before the camera has a chance to focus

06-20-2009, 06:52 PM   #5
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You can, however, use the AF button to let the camera release regardless of focus lock, at least with said button set up certain ways. There's also a combination of options you can use which will basically use the AF button to achieve focus *only,* and then you can release the shutter at will, even in AF-S.

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