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12-23-2011, 12:34 PM   #31
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QuoteOriginally posted by kaiserz Quote
@mattt Thanks for the explanation. To be honest, I don't really get it... maybe because I haven't encountered the given problem yet, or maybe I'm still too new to recognize. But I have a feeling that I've encountered this so far with my new main lens the DA 35 2.4 Cause 1 out of 5 shots that I take, only one is sharp enough to make me happy(I always shoot at F2.4 but is moving towards f3.5 for a much sharper image). Once again thanks (:
By far, the majority of primes are a bit sharper when stopped down a notch or two. Many many fast primes are a little softer wide open.

As for the issue with tungsten light, if shooting wide open and close to your subject, your depth of field is going to be very narrow. The band through your scene that's in focus might be measured in centimeters or less, with everything in front and behind that band being soft or blurred out. The issue comes in when you lock focus on your subject, but the band of focus is actually mm or cm in front of that spot, so you miss nailing focus on the spot you want, and the resulting photo focuses a bit in front of it. Hence, front focus.

Also remember that it's very very common while learning to shoot that you may miss quite a few shots when shooting with a large aperture. Sometimes the AF will lock on a different spot than you think it has, sometimes it'll just miss, especially in low light. The AF "points" are not points, they are zones, and the center one is almost as large as the center metering zone - larger than the red rectangle that lights up. Some of it will be user error, I know it has been many times in my own case. It handles very very differently than a point and shoot, and I found it to be quite a learning curve - I still do.

It can be a serious issue, but if you know you're going to be shooting under these conditions, there are measures you can take to mitigate it. One, switch to Live View, the contrast detection AF that LV uses isn't subject to this bug. Two, you could manually focus. This is up to your eyes, rather than trusting the AF module (although some people get by by acquiring lock with the AF confirmation (the green hex in your viewfinder) and then manually adjusting the focus just slightly to compensate for the tungsten bug. Three, you could stop down the lens. Using a smaller aperture increases the depth of field, so if the tungsten bug pushes it a bit in front, your subject may still be acceptably in focus.

So, if you're only shooting wide open with a fast lens under tungsten light occasionally, don't worry too much about it. Just use one of the above workarounds. If you have to shoot under tungsten all the time and can't use a slower lens (like the kit lens, for example) then a K-x or K-5 might be better for you. The vast majority of people with a K-r find a way around it that works for them, and are overall happy with the camera. Myself included. A few, well, a few get hung up on it being less than perfect, and a few genuinely NEED to shoot under tungsten all the time, but they're definitely the minority.

12-23-2011, 12:55 PM   #32
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@Philoslothical WOW that's an awesome read (: I learned a lot, and it's actually making sense now! Thank you so much.
12-24-2011, 11:15 AM   #33
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What Philoslothical said. We went with a K-x for our second cam.
12-24-2011, 12:48 PM - 1 Like   #34
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The K-x is a much better choice for Autofocus accuracy

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