Error message help!

viridian_vixen

This past weekend I switched over to my 75-300 lens and was shooting fine for a few minutes and then it started popping up Err 99 on the lcd screen. I turned the camera off and back on, shot again and same problem 2 clicks later but the pictures were all darker... So even though I am a noob I figured it was something with the fstop. But is there a way to fix it without sending it all the way back? Once I got back home from the trip I put it back on the camera and got a shot that was completely dark but a f/4 setting mid day... and then another error message. But the other lenses never pop up the error message. Used a 100-400 most of the weekend without a single problem (minus my left arm getting one hell of a workout) and my new 50 was working like a champ too.
I found a few things online that seem to say that a contact may have oils on it, but not real sure.
Any help would be greatly appreciated!

ziggy53

I recommend cleaning the contacts on both camera and lens. Even though this appears to be isolated to one lens, dirty contacts either on the lens or the camera can cause this error.

A clean red pencil eraser is pretty good to burnish the contacts. Don't use much pressure and make sure that any eraser dust falls away from the camera or lens openings. You only need to work on the surfaces that touch.

If this does not solve the problems try using the DOF preview button with the 75-300mm zoom attached. This attempts to send just the aperture information to the lens to verify that connection. If the error occurs during this test it's probably time to have the lens serviced.

viridian_vixen

Thanks for your help! I will definitely give it a try!