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Forum: Pentax News and Rumors
12-19-2009, 12:20 PM
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Most likely it's because the Tamron and Sigma lenses are available for every brand while Canon lenses can only be attached to a Canon SLR, Nikon lenses to a Nikon SLR etc... So surely many Nikon, Canon, Pentax, Sony and even Olympus users voted for Sigma, but it's unlikely that a Canon user voted for the Nikon lens.
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Forum: Pentax DSLR Discussion
11-21-2009, 03:59 PM
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And you call this a relevant test? It has nothing to do with our argument - F/22, infinity - you have to be kidding.
But I realized one thing. I was wrong, the main problem is, that you define DOF like you did, and with that definition, you were right all the time. But DOF is not relative, not subjective etc, but it is an exact, calculable value. There's an exact definition of DOF, you cannot define DOF to be something absolute different. In fact you can, but that will leads to misunderstandings, like this.
If DOF means that to you, we can't say anything to prove you're wrong, because you aren't. It's just that we think about DOF another way - the formal way. The official way if you like. (The official definition of DOF can be read in the second link I gave you before)
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Forum: Pentax DSLR Discussion
11-20-2009, 04:01 AM
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Forum: Pentax DSLR Discussion
11-19-2009, 05:14 PM
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As the others said, yes you can, but only the center AF point will give you focus confirmation, if you use a manual lens.
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Forum: Pentax DSLR Discussion
11-19-2009, 04:46 PM
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All of that is true. DOF will be different because the maximum permissible circle of confusion will be different. So even though the lens itself remain the same and none of its optical attributes will change, the DOF with different senzor sizes won't be the same. You should look after the meaning of circle of confusion, and its effects on the DOF. Once things become clear one can find it pretty logical, although I know it sounds like quite a stupidity at fist.
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