Error 99 Sigma EF lenses: the 180mm f/2.8 APO Macro
What can you do with a Sigma EF lens that can only be used wide open and you can’t find anyone to re-chip the lens?
Try stopping down this Sigma lens and an obsolete chip prevents you from taking a picture by displaying an “err99” code. In addition to this problem, the rubberized coating on the barrel has become sticky and attracts dirt like a magnet.
You can’t control the electronic diaphragm inside the lens without some type of electronic interface so one possible solution is an EF to MFT adapter with a built in diaphragm. It’s not the first time a diaphragm has been used behind the rear lens element; the 135mm lens for the Mamiya C330 had both a diaphragm and shutter behind the rear element.
A 180mm lens is equivalent to a 360mm lens on a MFT body because of the 2X crop factor. Here’s a cropped image of a dove from 6 meters.
Error 99 Sigma EF lenses: the 300mm f/4 APO Tele Macro
Another “obsolete” EF mount lens that only works on Canon film cameras is this Sigma 300mm f/4 APO Tele Macro.
Using an EF to micro four thirds adapter with a built in diaphragm, the lens becomes usable on a digital camera body.