Sigma 105mm lens - possible autofocus problem
Hi,
I just bought the old Sigma 105mm macro lens on Ebay (i.e. not the new
DG version) as it was going cheap (doesn't work with EOS digital, and
I'm still a film luddite). It's generally in good condition, though has
obviously seen some use. But I suspect the focus system may be worn and
wanted to check what's normal as I have a few days to consider
returning it.
Two things are bothering me. One is that there's a bit of play on the
focusing ring, and the other is that the autofocus works very slowly
when the ring is pulled down to the 'manual focus' mode, though I'm not
touching it. It works fine when the focus ring is in the autofocus
position, presumably because the mechanism has less friction to
overcome.
Googling around, I found one report of a worn belt inside of the lens
that was slipping and interfering with the autofocus. I wondered
whether my lens might be developing the same problem.
The lens seems to make two different noises whilst focusing. One is a
normal autofocus noise, and the other is a short high frequency buzz. I
presume the short buzzes are some sort of fine-tuning of the focus,
though I don't see the image change. I also considered it might mean
there was a fault with the autofocus, as sometimes when I try to focus
it just makes these noises and doesn't even seem to search for
something to lock on to.
If it's relevant, my camera is an Eos 300 (film).
Very grateful to anyone who can tell me whether I have a problem lens.
Kit Wolf
Kit
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