Originally posted by UncleVanya The FE 28/2 obviously has AF on the Sony and is more compact once you factor in the required adapter with the FA 31, but the FA 31 has the better rendering - I love it on my 42MP Sony sensor. I also find the FA 77 to perform very well (minus the well-documented fringing) on the Sony - just keep in mind the negative impact using Silent or EFCS shutter modes has on bokeh at fast shutter speeds.
Not on your list of lenses, but a couple other Pentax lenses I've enjoyed on the A7RIII are the SMC K 28/3.5, which performs extremely well on modern FF digital sensors with an unmatched flare resistance for a lens that old, and the M 120/2.8 as a great compact tele option for hiking/travel.
Originally posted by UncleVanya And sure the A7rIV is more resolving than the A7rII but I am using this as a guidepost. The 24-105 my dad has on loan is pretty spectacular he says, but I haven't compared images yet. He took some with the 28 and says he can't tell the difference on his laptop screen even zoomed in. Time will tell.
The 24-105 is impressively good for a zoom with that range - sharp at all lengths, good build quality etc. It does trade "character" for that sharpness, but it's hard to beat when you need one-lens versatility at a somewhat reasonable size without sacrificing much at all in the way of IQ