Originally posted by photoleet Your reading them wrong
If your willing to ignore klauses warning on cross system comaparason then you need to normalise the graphes
to do this your divide the resoltuion with the max chart scale so for 24mm F4
Tamron = 2050/2150 = 95% of max system resoltuion
Pentax = 2598/2750 = 94% of max system resoltuion
so the Tamron os sharper @f4 24mm ......But that only works if your using the lens on 8Mp
the reason is the lens may well have a max resolution (itself) of 2200 lw/ph you will not see this on 8mp but switch to 16Mp (2750) and the lens suddenly cannot rise to the requirements of the sensor.
SO you might see figure like
Tamron 2170/2750 = 78% of max resoltuion
I'm not saying that is what would happen but that is why you cannot cross compare MTF figures.
You need to interprate them as a trend and be aware the lower the Mp tested the easier it is for a lens to shine.
In your two examples I woudl summerise as
The Tamron easily out performs the Pentax at the wide end where the Pentax edges are well beyond soft.
by 24mm the Pentax has caught up and portentially passed the Tamron give the Mp differences but still the Tamron has f2.8
once past 24mm the Tamron again shows it superioirty
But bear in mind this is a single lens and the images I've seen from the Pentax are not indicative of the results Klaus obtained being considerably better across the frame than those MTF figure would show.