Canon extender with Tamron lens question

[Pauly_6_String]

Hi all.  I just picked up a used Canon EF 1.4x II extender and attached it to a Tamron G2 70-200 f/2.8 lens.  

The camera displays f/5.6 to f/45????   Exactly two stops high on each end.  Is that a compatibility/communication issue between the two brands?

Also was disappointed to find that it won't fit my EF 17-40 or my EF 24-105 lenses.  

thanks

[ebiggs1]

Keep in mind, using a tele-con does not change the physical aperture. You are magnifying an image that is already projected by the lens. The physical aperture is unchanged so the depth of field is unchanged.

[kvbarkley]

Since the "circIe of confusion" is changed, I think that the DOF is changed too, just like the fact that the DOF changes when you use the same lens on FF vs APS-C.

ETA:

This is wrong, the change in depth of field is entirely due to the effective increase of the focal length.

[ebiggs1]

You are talking sensor. I am talking lens.