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Forum: Pentax DSLR Discussion
01-05-2012, 03:32 PM
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It does not matter what the grid is for, it matters how it is used in this particular case. And in this case, it is not used to determine focusing accuracy, it is just an element of the photographed scene - they try to focus on it, but they can't use it to determine the focus accuracy - that would require the grid to fill most of the frame.
I'll have to disagree on this too, because I think that "agreeing to disagree" is just plain stupid. We don't have to agree on anything, so we don't need to appear as if we're agreeing on something. I just like to provide arguments for arguments, so don't take my replies as an effort to convince *you* - they are for other readers as well. I like to debunk fallacies. When I get bored or too busy, I don't bother anymore. But I never, ever, "agree to disagree". I am getting a bit bored though.
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Forum: Pentax DSLR Discussion
01-05-2012, 12:15 PM
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It's not amazing, it's called confirmation bias. I look at an area where one shot is clearly getting out of focus in the front and I conclude that that shot is backfocused compared to the others. You ignore that and you're instead pointing at a tiny area where all shots appear in focus and you conclude that they are all focused on the same exact spot.
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Forum: Pentax DSLR Discussion
01-05-2012, 02:58 AM
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No problem, my goal is not for you to agree with me.
The dpreview K-5 shots are backfocused compared to the K-x/K-r ones. Anyone can see it in the ISO 200 shots when noise doesn't muddle everything - the bottom of the piece of paper is telling: in the K-5 shots the lines are already fading out of focus. That is why if we look in the back of the scene, on the Q card, for example, the K-5 shot will look sharper, but in the front, on the watch face, the K-x shot will show crisper detail. Again, you don't have to agree - I'm including the snippet for general reference for anyone interested in the argument.
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Forum: Pentax DSLR Discussion
01-02-2012, 09:25 PM
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Their shots are proof of this. I looked at enough test shots on both dpreview and imaging-resource to realize that maintaining the same focus is not part of their goals. It may happen in some shots, but it is not guaranteed to happen by their testing methodology. Thus, it is important to verify that focusing does indeed happen in the same area, before you can use their test shots to compare 100% crops. At 100%, the perceived DOF is small even at large apertures and particularly for high ISO shots where details are lost to noise, it is important to make sure that you are actually seeing the differences caused by noise instead of differences caused by focusing.
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Forum: Pentax DSLR Discussion
01-01-2012, 08:27 PM
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No. The problem is that the dpreview test shots are taken with *NO* care for maintaining the same focusing across tests. I don't know if they even use manual focus or they let the AF system decide where to focus. I don't think they maintain the same focusing even within a test for different ISO shots - much less for different tests done weeks or months apart.
If you cared, you could set down the tripod at a fixed distance from the scene, place the two cameras on it, and take two shots while focusing in the same place - using live view for example to ensure focusing precision. Then you could compare shots focused the same way and you could pick your crops from the in-focus areas.
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Forum: Pentax DSLR Discussion
12-31-2011, 10:37 PM
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A problem with such shots is that they are taken at different times and a small difference in focusing can mean a lot when comparing 100% crops.
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Forum: Pentax DSLR Discussion
12-31-2011, 01:56 PM
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I think we're talking about different things then. In practice, I rarely go over ISO 800 and I only once used ISO 3200, more out of curiosity than anything else - ISO 1600 is my hard limit.
But what I was asking was this: if the K-x shows better DR at ISO 12800, isn't that a positive thing vs. the K-5 at 12800? Everything else comes about the same in the other graphs.
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Forum: Pentax DSLR Discussion
12-30-2011, 11:46 PM
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That looks like the kind of information I always wanted to know, but I'll need some time to digest it.
I guess what I am missing is this: ok, there is less fine detail in the smoothed shadows/highlights, but at least there is some, vs. the alternative of clipping them. I guess you might be saying that the loss of detail to clipping is more negligible compared to the loss of detail elsewhere due to NR? Is that it?
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Forum: Pentax DSLR Discussion
12-30-2011, 10:10 PM
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Yes, I remember that thread. However, that one started with dpreview's comparison and while dxomark was mentioned briefly, no one pointed out that their results actually support those of dpreview.
The curves always change when the smoothing occurs, but it's interesting that the K-x one manages to overcome the K-5 one. And since this is the DR curve, I'm not sure we can say that the K-5 can retain more detail if it actually has less DR - it may retain some fine detail, but it may lose detail in shadows and highlights.
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Forum: Pentax DSLR Discussion
12-30-2011, 03:34 PM
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I was checking the dxomark test results when I noticed that the K-x performance is getting very close and in some cases even gets better than that of the K-5 at high ISO.
Basically, starting with ISO 3200, the K-x graph starts getting closer to the K-5 one and in the case of dynamic range even surpasses the performance of the K-5 at ISO 12800 (despite a larger gap at lower ISOs).
Pretty interesting behavior.
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