ramblin21 Loc: Sharon,Wisconsin

I have a Sigma Zoom 100-300 1:4.5-6.7 DL 55mm, AF/M lens with a Canon AF Mount with a built on lens shade.
My problem is it does not work correctly on my Canon T4i, it will focus in-doors, but is never sharp at any focal
Length. Outside daytime or night time it does not work at all. It gives at times an error message to turn off camera an back on, this does nothing to help. Could this lens be for a 35 mm SLR? And not for a Digital camera? Or what could be wrong with it? If I shake the lens it makes no noise so I would assume that nothing internally is wrong.
But I could be wrong about that also. Any assistance would be greatly appreciated. Not sure what I should do with it. Or if it is worth the bother to see if I can get it fixed if it is for use on a Digital Camera. Thanks in advance for any help. Hal

MT Shooter Loc: Montana

I will guess you are using the lens at the long end (300mm) and it will be an F6.7, Your camera will not accurately AF at F6.7. Use the lens at 100-200mm and it should AF just fine on your body. Yes it was a film lens when introduced.

ramblin21 Loc: Sharon,Wisconsin

Thanks MT Shooter, but I tried at 100 and it does not work, it did tell me
Communication error 01 cannot communicate with camera clean contacts, i have done that several times and its no go. I think its a bad lens, but I don't have a 35mm slr to try it on to see if that might help.
Thanks for the quick reply. Hal

ramblin21 Loc: Sharon,Wisconsin

Hello MT Shooter: my T4i was out for repair as mirror would lock up when taking a pic, but would not release mirror until I turned off/on an mirror would release. With less than 3300 on camera I sent it back, now camera is fixed. Canon diagnostics report was Shutter was bad and Replaced, but included that camera had errors for 100-300 lens an said to check lens. So I was right, tried it once or twice same problem with lens. This is going in the Garbage, I won't pay to have it fixed. It only cost me a days work painting my brothers deck, he had same problems with lens. Thanks for your help. Hal

MT Shooter Loc: Montana

Its quite an old lens, failures are to be expected as no one knows how it has been treated. Glad your camera is working now though.