Teleconverter question

[Migs]

Does anyone know the reason the Canon 100-400mm only work on "M focus"
when attached to a Teleconverter?:thinking:

[Canon Bob]

You'll only get AF on a 1srs body unless the teleconveter is a non-reporting type or you tape over the pins.

Bob

[Migs]

Thanks Bob......
what do you mean tape over the pins....(I understand what it means but how?)

[Canon Bob]

By taping over three of the pins the body doesn't know that the T/C is present and hence it will still attempt AF. The downside to this is the risk of burning out the lens focus motor due to excessive hunting.

Bob

[mav]

taping the pins works ok on the 1.4
but i couldnt get it to work on the 2x
just hunts back and forth

[Migs]

Thanks very much boys....
But, if there is a risk of burning the AF motor..........I will not attempt to do it....I've got more brains than money :)

[jimybell]

Had me going there for a while, the tape is back on the shelf, 5D with 100-400, too many £££'s involved, too much saving up to get them!
Jim

[Migs]

Had me going there for a while, the tape is back on the shelf, 5D with 100-400, too many £££'s involved, too much saving up to get them!
Jim

Quite right Jim

[lammie]

Bob if you tape the three pins and then shoot with MF selected on the lens instead of AF (By doing this you can still retain the focus signal when you half depress the shutter button as you are focussing manually whereas you don't get this signal if AF is selected), would you think that this has any detrimental effect on the AF motor in the lens.