Monday, April 4, 2005, 9:28:06 PM, Kostas wrote:
KK> On Mon, 4 Apr 2005, Jostein wrote:
>> IMHO, there are only two samples that qualify as "useless mush"; the FA*
>> 28-70/2.8 at 28mm and the A645/2.8, both at full opening.
KK> I am not a great photographer, but these would be useless even for me.
KK> I know nothing about the A645, but with the FA* I am really
KK> unimpressed. Is it like that on film as well?
I know nothing of the FA* 28-70/2.8 (except that it uses a rather
intimidating lenshood that doubles as a beer mug when you put the cap
on it <g>), but that is certainly too mushy. I can think of two
possible explanations (except that the lens is bad or bad sample):
1) focus - was not right. At infinity and wide open, depth of focus is
the narrowest ever, so even small misfocus shows a lot. AF can't
effectively focus on infinity. Even Leica can have problems focusing
on infinity. So the AF system might have chosen a slightly different
distance, which simply was not in the depth of focus.
2) big curvature of field, causing again the selected crop to be out
of focus range. As this is a _reportage_ zoom by all means, such a
thing wouldn't be a problem in its intended use - reportage - that
much, but would be obvious in landscapes at infinity and wide open.
Rarely one has to shoot an infinity landscape at wide open aperture :)
Remember, you are looking at 1:1 pixel crops, accounting to big
enlargement. DOF computed for standard enlargement ratios doesn't
apply here at all.
Good light!
fra
