So I like to compare lenses of similar range focal length for
IQ in the first, and all the other bits and pieces secondary and think it would help having some side by side comparisons done on a whole lot of Pentax lenses.
I saw the recent FA*80-200/2.8 vs Sigma 70-200/2.8 vs Tamron 70-200/2.8 and was thinking along these lines (personally I think it was a lost opportunity not to include the DA*60-250/4 in this test as a comparison given the FA* is no longer available new and the DA* has an overlapping zoom range). I also think it doesnt hurt to compare zoom lenses of different ranges, both for where they overlap as well as where they go further in FL (or max aperture) than the other - visual comparisons are great in this respect for contrast, bokeh/isolation etc. The wall-chart stuff for pure science as well as 'real world' outdoor/indoor image examples would both be very useful.
When the new DFA100 Macro came out - it nailed my choice to go for the DFA over the FA due to the rounded blades - thanks to the person who did that (apologies for forgetting) it was great!
I tried to check here recently re DA*16-50/2.8 vs DA 17-70/4 comparisons but to little avail... And although there have been plenty of these threads I know, most are anecdotal at best and heavily biased toward the responder's use of the lens.
Anyway, the side by side IQ/etc comparisons i'd *kill* to see are:
Primes:
FA 50/1.4 vs FA 50/1.7 vs DA* 55/1.4
FA 43/1.9 ltd vs DA 40
DA14/2.8 vs DA15/4
FA 77/1.8 ltd vs DA70
FA 35/2 vs DA 35/2.4 vs FA 31/1.8 ltd vs DA 35/2.8 macro
Zooms:
DA* 16-50/2.8 vs DA 17-70/4
DA 50-200 vs DA 55-300 vs DA 18-250 (the latter primarily for the 50-250 range)
and as above, the 70-200/2.8 vs DA* 60-250/4
There's also the option of some of the third party lenses beyond that, eg Sigma 50/1.4 & Sigma 30/1.4 against the respective focal lengths...
Would love to be able to get my hands on all the glass to do myself
but alas
Could be useful for people to really get their heads around what to expect from each lens before they go out and buy. All the stats about diffraction and autofocus speed are great and objective, but sometimes you need to compare the subjective in a more measured way... if that makes sense!