Originally posted by jjfdvm72 I suppose you have been facing the underexposure problem of your camera but I'm afraid this tendency is just normal for ALL Pentax DSLRs (same or different models AND same or different units) which I have used since 2003.
Here are more test samples and evidence that re-verify and re-confirm the case:-
RiceHigh's Pentax Blog: Underexposure Tendency of K10D and K100D
As for the solution to the problem, as I have said in my homepage, is to use fixed pattern metering and apply proper +EV compensation for each of the Pentax lenses you own and know about the compensation value for each of the conditions, e.g., outdoor or indoor, daylight or tungsten etc.
Below is a direct link to the measured test data for the K100D for its exposure accuracy, I found that the Centre-weighted average metering is the most consistent in results. As such, if it will be more easy to apply a fixed EV compensation without worrying to change the value significantly from frame to frame so oftenly if you use the CWA metering:-
RiceHigh's Pentax K100D Full Review
In short, as a few others responses have pointed out, you need to ADAPT for your DSLRs. Frankly, if you have a Pentax film SLR or a Canon / Nikon DSLR, the results would be more close to be correct or at least more acceptable by default in different situations or with different lenses and life will be much easier as such when much less compensation and adjustment works are required *during* shooting.
Another way to "solve" the problem is to shoot RAW and then compensate when convert, but you will never get the best image with more grey details and least noise if you do so, just see again the famous Luminous Landscape article below:-
Expose Right