Originally posted by Class A What really matters, AFAIC, is how the K-5 performs with 1.03 in absolute terms. Comparisons to 1.02 might be interesting in order to find out what Pentax did, but isn't it much more relevant to determine in what situations 1.03 still fails?
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I'd like to learn how the K-5 compares to other cameras like the K20D or K-7 in terms of front-focusing in low light. The question for me is: Is the K-5's AF worse than that of previous Pentax cameras in some situations or is it not?
You're right.
However, what actually bothers me is that the K-5 AF locks (and pretty fast so) in situations where it is unable to aquire the
correct focus.
It would be a big improvement if the K-5 just gave up then. After all, a photographer needs to trust his tool.
I wouldn't be surprised to learn that other cameras like K-7 or competitors actually won't lock focus either in similiar situations then.
It cannot be a problem for the firmware to know that colorimetric info is insufficient and make the AF give up. Or at least, to make this behaviour a menu option.
The K-5 meter gives up too: there are longest exposures the meter cannot exceed (it is -1EV at f/1.8 and +2.3EV at f/5.6). Interestingly, this is about where the focus shift happens with my white target. I.e., the firmware knows where the meter operates out of spec. It doesn't create random meterings but conservative ones (leading to underexposure). So, why not make the AF algorithm include code to fall back to a conservative choice (like no lock) in the same situation?
It is ridiculous that the AF continues to lock up to 4 EV below where the meter still works... (because it obviously
needs the meter for a correct focus).