trumpet_guy
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I'm sorry to hear of the bad experiences people have had with Sigma.
I just got my Sigma 50/1.4 back from Joseph James, who had been
borrowing it to test it out. A lot of things came up, and he wasn't
able to test it much for himself, but his conclusions were:
1. He hated the color performance. [Can't see why he
picked on this. I like the colors quite well.]
2. AF was erratic. [I'll address this below.]
3. When it nailed the focus, the f/1.4 performance was fantastic.
[No argument here.]
I just shot off 50 or so pictures with this lens on my 5D using autofocus,
the vast majority wide open. The results for my lens-body combination:
Quite good.
Reading about all of the backfocus problems people had, I was keen
to test this. My copy seems to have very little of this problem, though
it can sometimes be seen at distances of maybe 50 feet or farther, wide
open. I will do a more thorough evaluation soon, but I'm still quite happy with
the AF performance of this lens, and it seems as good as almost any
Canon lens I've used. I won't say it is flawless, but then again I don't
think Canon's AF system is capable of flawless performance at f/1.4 so
I'm perhaps less likely than some to assume the lens is the root of the problem.
I will not discount anyone's experience here. Some have evidently gotten
poor AF performance and I won't claim it's user error. I am just thankful that
mine is performing very well; this lens is a real pleasure to use.
In fact, from the few shots I've taken using AF, I would not have thought
it has any AF problems if I had not read about it on the forums. Once again,
not to say forum users are all wrong, only to say that not every copy has major
AF problems.
Now, even if there were major AF problems with my copy, I'd likely hang onto it
for a while and use it in manual focus mode, since it is optically _fantastic_.
[Mine is an early model: serial number 10014xx, if anyone is curious.]
It would be in Sigma's interest to take user feedback seriously.
This lens is optically too good to allow reports of AF problems to
limit sales of this glass. I think I will soon be selling almost all of my other
50mm lenses. My copy really is that good.
As for the AF issue, I did have some out of focus shots among the 50 I shot.
I was most likely to see it when the subject was far away -- 40 or 50 feet or more.
When the subject was at true infinity focus distance [150 feet or more], the AF
usually got it right. And the problem with backfocusing that people were
seeing at 10 feet -- no trouble with mine. I tried a number of shots of a sign.
Shoot, back up, shoot, back up, from 5 feet to 15 feet. Each one nailed [f/2.8
on these, so admittedly not the absolute worst case test]. At f/1.4 I shot
three-in-a-row of a car license plate at 25 or 30 feet away. One was super sharp,
the other two were close, but not perfect, but still pretty good.
I will need to shoot more shots, though, as 50 shots is a small sample.
I am aware that some people have found conditions where
their lens consistently backfocuses. I have not seen that, but I'll need to take
repeated shots at around 40 feet to 60 feet range to see that for sure.
Anyway, I hope to get some tests done soon over a range of focus distances and
compare its AF performance against the Canon 50/1.4 on my 5D. For those of you
who have been wanting this Sigma glass, I think my lens and Chez Wimpy's and a few
others' give us hope that Sigma can make it work.
Tim
Edited on Aug 08, 2008 at 05:09 PM
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