Dead Canon 1.4x extender

[Coot]

Got it for my 5d/100-400 combo. AF works and focus point indicators light without the extender, but none of the electronics work when the extender is inserted. Before I send it back, is there something I may have overlooked? (I'm new to DSLR.)

[stever]

the 100-400 does not work with the 1.4 extenders by Canon design

the three clockwise contacts (viewed from the camera side) tell the camera what lens is fitted and Canon disables autofocus for anything greater than f5.6

some camera and lens combinations will focus with extenders at f8 if these three pins are taped

my 100-400 with 1.4x will focus reliably but slowly on my 20D, but will not focus reliably on my 5D (pins taped)

[Coot]

Thanks, Stever. I somehow missed that little caveat in the description. Manual focus and crossed fingers it is...

[stever]

sorry to mention this, but my 100-400 doesn't isn't very sharp at 400mm with the 5D (my 20D at an equivalent 400mm is as sharp or sharper with this lens)

the 20D with the 100--400 +1.4x is useable (good 8x10 prints with careful work - after all, this is  900m equivalent).  If you really need a long lens (without buying a 300 2.8 or longer), i'd recommend buying a 30D or used 20D body.  The only way i could better the 20D and 100-400 was with the 5D and rented 300 2.8+ 2x (which i'm not willing to carry)

i try to use the 5D up to 150mm (i don't have a 70-200) and the 20D for the long end