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12-31-2010, 02:56 PM   #1
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K-X focus strategies

I apolgize if this has been covered before (couldn't find anything) but I just got rid of my k100d and picked up a new navy k-x. One thing I enjoyed with my k100d was the illuminated focus points in the viewfinder . I would also use the directional arrows to choose my focus and then focus and shoot - this seemed to work well for me. I never really got into the focus/recompose because I felt like if you focus on one point and rotate the camera to recompose it changes the focus slightly. Anyways, I'm wondering how people are focusing on the k-x without the k100d style options. It's still new to me so I haven't got to experiment much but I'm wondering what's working for everyone.

12-31-2010, 03:29 PM   #2
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Most people set the centre focus point, and then use focus and recompose.

Lots of other strategies have been found useful, though. Some say letting the camera pick the focal point works well for dynamic scenes even though you sometimes miss shots due to the camera picking the wrong one.

You can still select specific focus points with the view finder - you just have to learn where they are.

Some use Live View (which does show focus points). That can be especially useful when shooting a fairly static scene with a tripod.

And some people use manual focus. Some switch to manual focus, set the hyperfocal distance and a fairly narrow aperture, and then rely on everything beyond a few feet being in focus. That can be good for candid or street photographs.
12-31-2010, 04:29 PM   #3
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Hi menappi,

Focus and recompose only falls down when using very fast lenses at the largest apertures, and at close distances where DOF is the thinnest. How you choose to shoot is your decision, but you might be allowing imagined precision to outweigh practical focus accuracy. Consider that with film, the only focus aids were split image and microprisms in the center of the screen, and lenses were no less sharp nor did they have shallower DOF. . .

The Kx allows you to program the green button to center the AF point, and from there, it's only a maximum of three button presses to any other focus point, so you can train yourself to automatically return the point to center and still choose a focus point without taking the viewfinder from your eye. If you need to confirm the focus point that you had previously chosen, you can do that on the status screen. This should only be a minor inconvenience.

Scott

Scott
12-31-2010, 08:19 PM   #4
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I find the center spot, focus and recompose to work the best. I also initially thought that this practice might change the focus slightly but after many many photos and pixel peeping I do not think this is the case. I get very sharp photos using this technique.

01-01-2011, 01:57 PM   #5
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QuoteOriginally posted by snostorm Quote
Consider that with film, the only focus aids were split image and microprisms in the center of the screen, and lenses were no less sharp nor did they have shallower DOF. . .
Just for clarification -
for the same angle view
the smaller format APS-C will have a greater DoF than the larger full frame 35mm format.

For the same lens - as you say will have the same DoF -
eg: a 50mm lens at the same aperture will have the same DoF -
However in practice, that lens gives an angle of view on the 35mm film camera of 50mm a "normal lens".
BUT on an APS-C this is the equivalent of 75mm (adjusting for the crop factor) and is really a short telephoto.

To get the same angle of view the APS-C would have to use a 33.3mm lens - and that will have a greater DoF at the same aperture.

Please see: DoF at Wikipedia

" When the “same picture” is taken in two different format sizes from the same distance at the same f-number with lenses that give the same angle of view, and the final images (e.g., in prints, or on a projection screen or electronic display) are the same size, the smaller format has greater DOF. "

BUT it's unfortunately slight more complex than that:

" Many small-format digital SLR camera systems allow using many of the same lenses on both full-frame and “cropped format” cameras. If the subject distance is adjusted to provide the same field of view at the subject, at the same f-number and final-image size, the smaller format has greater DOF, as with the “same picture” comparison above. If pictures are taken from the same distance using the same f-number, and the final images are the same size, the smaller format has less DOF. If pictures taken from the same subject distance are given the same enlargement, both final images will have the same DOF. The final images will, of course, have different sizes. "
01-01-2011, 02:56 PM   #6
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QuoteOriginally posted by UnknownVT Quote
Just for clarification -
for the same angle view
the smaller format APS-C will have a greater DoF than the larger full frame 35mm format.

For the same lens - as you say will have the same DoF -
eg: a 50mm lens at the same aperture will have the same DoF -
However in practice, that lens gives an angle of view on the 35mm film camera of 50mm a "normal lens".
BUT on an APS-C this is the equivalent of 75mm (adjusting for the crop factor) and is really a short telephoto.

To get the same angle of view the APS-C would have to use a 33.3mm lens - and that will have a greater DoF at the same aperture.
What you're saying is, of course true, but this only serves to make my point -- that center focus and recompose is more than sufficient for most people, with most lenses, most of the time, especially since APS-C has deeper DOF for a given perspective/FOV.

Relatively few people have lenses fast enough and shoot close enough to make this a real issue in practice, and for those situations, the Kx offers selectable focus points and provides a way where the photographer can easily choose a focus point without taking his eye from the VF -- they just don't light up. The lack of focus point indicators has been way overblown as a practical downside for the Kx by "professional" reviewers trying to flex their technical chops over a"missing" feature in an entry level body.

Scott
01-02-2011, 12:51 AM   #7
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I've found that the five point auto focus works well for anything more than 10 foot away. It speeds up the focusing and the depth variation in the small area that is covered by these five focus points does not show up in a photo. For exact focusing, closer up, I use the centre point method. The absence of focusing lights in the screen makes no difference but I had to learn to check that the focusing hexagon has illuminated at the bottom of the VF.
01-13-2011, 09:48 PM   #8
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Most of the time the 5 point AF works great for me. When it doesn't, I use the selectable focus points ... it's just an Ok button, and then a few direction arrows away.

I've only used the MF with my kit lens a few times, mostly with close up of flowers, etc.

I don't see the lack of AF points in the VF as much of a problem so far.

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