I have a Sigma 24-70 2.8 EX DG Autofocus will not work.
I just got this lens for Christmas 07 with less than 100 pictures on it and now the autofocus doesn't work. When I depress the button it slightly moves around infinity symbol but that is it. Sometimes I can depress the button all the way and it wont take the shot. I can manually focus and when I move the focus ring from manual to auto ever so slightly I feel & hear a click. Then sometimes it will focus but inevitably ends back over at infinity. I have it on a Canon 20D and my Canon 70-200 2.8 has no trouble when I attach it, regarding focus. I bought this lens because the price was better, I;m beginning to wonder if I get what I paid for. Any thoughts.
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Re: I have a Sigma 24-70 2.8 EX DG Autofocus will not...
Call Sigma. Here is the information. They will be able to help you for sure.
To request assistance by phone in the US, their technicians are available from 9AM to 5PM Eastern Standard Time, Monday through Friday. Please call: (631) 585-1144.
Customer Service Department call toll free (800) 896-6858.
You can also fax them 24 hours a day. Fax: (631) 585-1895 or (631) 585-7661
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Assuming you've made sure the auto-focus is turned on on both the lens and the camera, remove the lens, turn off the camera. Remove the battery. Wait about a minute. Put the lens back on, turn the camera back on . It's a computer basically. Sometimes it crashes. I've had this happen to me a few times.
If the gears are stripped, it will require an experienced tech to repair.
That being said, there should be a small switch near the lens mount to switch between auto and manual focus mode's, be sure that that switch is pointing to A. When set to M, the little screw recesses into the mount so it doesn't try to engage, when set to A, it'll extend very slightly.
Also, Nikon has manufactured two types of AF lenses - with the motor in the body and with the motor in the lens, as with most newer lenses. Your camera should have a small screw on the lens mount that drives the focus motor between the lens and the camera, but I'm not 100% certain on that. Your camera can focus lenses with and without this type of coupling. BUT, if that screw/motor in the body is not functioning, you'll only be able to use lenses which contain the focus motor inside them, or manual focus lenses (you can manually focus AF lenses too).
That lens has a coupling on the lens mount which you'll see rotating when you alter the focus ring and look at the back of the lens. it does not have an in-built focus motor and so will only autofocus with Nikon bodies which incorporate a mechanical AF coupling on the lens mounting flage.
I would send it into sigma. They are in NY,
They are really quick about checking things out and I have neverhad them charge me to look at a lens and tell me whats up. aot of times they will just fix it while it there is it looks like something is worn out from normal use.
its a great lens. Some would say its a slower focus. than the Canon brand and you do get what you pay for but its hard to spend as much on canon lenses as they want. :)
The evolt cameras use the flash bursts as a "autofocus help". Try to find points with high contrast or edges to point one of the three autofocus points at (you see these points while looking through the viewfinder and they flash red as soon as the camera is focused).
So, flash bursts basically mean "too low light" some other situation which is hard for the camera to focus. In such situations, try to switch to MF mode (manual focus). Or you could buy an external flash (e.g. Olympus FL-36) which has a red light for autofocus assistance instead of flash bursts.
Fuzzie picture -meaning out of focus?
Check that you have not got
1- macro setting on
[setting symbol looks like a tiny plant]
or that you have a low light setting which menas it is taking long exposures.
Aslso the Auto foxus may not be function as it should - one possibility is that the way you hold the camera covers the 'window'
make sure your fingers are aware from any of the front top panel 'windows'
When you depress the shutter part way down- does the lens 'motor' to focus
Or indeed are you doing part way or are snapping off shot and giving the camera time to focus?
Lots of thing for you to check out, before we start getting worried.
The difficult ones are if the camera has taken a knock and the lens mount has become dislodged
But do all the check first and do consult the manual