Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Canon EOS dSLR

Reply
 
Thread Tools Search this Thread
Old Mar 30, 2008, 12:19 PM   #11
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

Make sure you're getting a good electrical connection, too (I'd clean the contacts on the camera and lens and/or remount the lens a few times to make sure it's got a good connection to the camera body).


JimC is offline   Reply With Quote
Old Mar 30, 2008, 12:22 PM   #12
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

Yes, it could need rechipping. Sigma reverse engineers the lens communication protocols and sometimes gets it wrong.

But, I got the impression that the lens was working correctly when you first got it, right?

If not, it could just need rechipping to be compatible with the camera. The 18-50mm f/2.8 isn't that old (so, I would have thought it would be fully compatible with DSLR bodies). Also, most of the time when a lens needs rechipping for compatiblity, autofocus is the issue, not exposure (as in the aperture not closing).

When the way a lens is chipped is an issue, Sigma will usually fix it at no charge (at least in the U.S.) for lenses they can rechip (and they can't rechip some of their older lenses).

JimC is offline   Reply With Quote
Old Mar 30, 2008, 1:26 PM   #13
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

DCMountaineer wrote:
Quote:
I was recently in Europe, where it was very cold; and that is when I started to encounter the aperture issues. May the cold weather have something to do with this?
If you have oily aperture blades, the oil can eventually congeal, causing the blades to stick (or in some cases, just become sticky versus totally stuck, not snapping closed and open as they should). So, cold weather could have caused a problem.

Or, you may have a component failure in the lens causing it.

But, from your symptoms (correct exposure at f/2.8 in Av mode, overexposure as you stop down the aperture more, aperture not closing using your depth of field preview button), the blades are stuck leaving the aperture wide open at f/2.8 from some kind of issue with the blades or a lens component.

If you call Sigma, they could probably tell you if it's a problem with the way it's chipped by the serial number on the lens. But, I think a problem with the way it's chipped is unlikely if the lens is working properly except that the aperture is staying open regardless of camera settings.


JimC is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 5:11 PM.