Originally posted by Denis Mine tested perfectly for BF/FF at 24 and 60mm with F2.8 settings.
through 4 Sigma zooms and 3 Pentax bodies (*istDL, K10D, K20D) I am yet to see the combination
that does it precisely and w/o AF adjustment
for both daylight
and genuine ("yellow") tungsten through all focus length'...
well, here is a quick daylight testing under the daylight (K20D, tripod, SR off, remote control, etc),
PP'ed in attempt to make it more visible (in focus/BF/FF).
warning - the image is WIDE.
24mm->28mm->35mm->40mm->50mm->55mm->60mm
note that 24, 40, 50, 55, 60 looks more or less OK, but 28, 35 are not... I will retest these 2.
click below and then click it again there to see the full size