I know I saw a thread about this issue before but for the life of me I can't find it now.
I'm having an issue using my T1I, EF100 f2.8 and extension tubes. Everything is fine with 2 tubes but if I add a 3rd, I recieve an error. I've tested with multiple light sources and have the same outcome.
The tubes are Pro Optic from Adorama... should I return them and get Kenko? Or is something else at fault?
Thanks in advance for any help.