[budkid]

I bought a Sigma 28-105mm f2.8-4 on flebay. I took it out, and there were some problems. The "A" setting on the lens does not put the lens in "A" setting. While I am shooting photos, I could twist the aperture ring hard clockwise to make it go into "A" setting. But it does not stay. I could use the lens in manual mode with the use of the green button. On aperture mode, it will not shoot at the aperture selected on the lens. What should I do? Send it in? Any tips or things I should know?

[Lowell Goudge]

I bought a Sigma 28-105mm f2.8-4 on flebay. I took it out, and there were some problems. The "A" setting on the lens does not put the lens in "A" setting. While I am shooting photos, I could twist the aperture ring hard clockwise to make it go into "A" setting. But it does not stay. I could use the lens in manual mode with the use of the green button. On aperture mode, it will not shoot at the aperture selected on the lens. What should I do? Send it in? Any tips or things I should know?

You might try cleaning the contacts on the lens mount, as they could be dirty.

To due this use a soft pencil eraser, not an abrasive one.

If that does not wirk, then I suspect the lens is defffective, or needs repair internally for the automatic apature switch.

You should retrun it in that case. If the lens can remain in A mode then the apature will work correctly