Hello there. I'm new to photography. Since I intended to learn photography I purchased an used Canon AE-1 with a bunch of lenses and filters.

During my long trip to Brasil, I took over 500 photos. To my surprise, after I've got the pictures back from the lab, I noticed an strange vignetting problem in many pictures. Since I din't make a log about lens, shutter and aperture used, I cannot tell the spechs of there pictures.

Take a look at an example:

http://pg.photos.yahoo.com/ph/erich_...65.jpg&.src=ph

What causes that problem? I would guess at it may be the use of a 2x teleconverter with the 75-150mm tele, but I'm not sure. Or maybe it's one of the lenses that are faulty...but vignetting din't show up on many other puictures...

Does anyone have a solution? What's the problem?

Thanks.

Erich