Originally posted by Kolor-Pikker From the little I've been using the 120mm and 150mm lenses on my 645Z, it seems that they perform fairly well, but near wide-open they are close in performance to the 55mm SDM, which is a newer lens. It would leave me to believe a wide being sharper than a tele and macro means that the latter are under strain to resolve 51MP, at least at f/4, but stopped down to f/8 or lower they are all fairly good. On a 40MP sensor I reckon you should see less artifacts, but the Z aches for top lenses.
(sorry for double post)
Ok, so I did the dreaded thing and shot my lenses against a test chart in 1-stop aperture steps, I won't post the images, but here are my findings:
FA 150mm f/2.8 IF
f/2.8 -> f/4 Not much difference, a bit sharper
f/4 -> f/5.6 Massive difference, almost like a different lens
f/5.6 -> f/8 Sharpens up by almost as much as much as going f/4 -> f/5.6, crazy sharp and likely fully resolves sensor
f/8 -> f/11 No difference
f/11 -> f/16 No difference
Notes: Jump in sharpness is quite abrupt, especially in the corners.
FA 120mm f/4 Macro
f/4 -> f/5.6 Slight improvement
f/5.6 -> f/8 Slight improvement
f/8 -> f/11 Slight improvement
f/11 -> f/16 No difference
Notes: Surprisingly less sharp than the 150mm by a not-insignificant amount, and more CA.
D-FA 55mm f/2.8 SDM
f/2.8 -> f/4 Slight but notable improvement, corners so-so
f/4 -> f/5.6 Good improvement but corners still so-so
f/5.6 -> f/8 Good improvement but corners still so-so
f/8 -> f/11 Corners clean up a bit, probably won’t get better than this
f/11 -> f/16 no difference
notes: clearly some field-curvature is going on, since I couldn’t get the corners perfectly sharp on the chart; it has more CA than 120mm or 150mm as well.
Consensus:
Per-aperture value, the 55mm and 150mm lenses feature similar performance, with the 150mm being superior in terms of corners and CA control, and the 55mm arguably having more center sharpness at least until f/5.6.
The FA 120mm f/4 Macro is strangely a dog, it is noticeably less sharp than either of the other two lenses at equal aperture, the 150mm is as sharp at f/4 as the macro is at f/5.6, although the macro has better corners slightly.
I
may end up not keeping the 120mm, but only until I get the 90... who knows when the macro capability might come in handy?