100-400 L IS + 1.4 extender

Am I correct that I should still have AF when shooting with the canon 1.4 extender? Right now the only way I can seem to shoot with this combo is in manual.

Confused in WA

Tom
Auburn, WA

You lose AF with a 1.4x extender because you lose 1-stop of light... f/4.5 turns into f/6.3... Unless you have a 1D, you lose AF at anything greater than f/5.6.

I always thought you lost AF with a tele extender but let me tell you what a little experimenting showed me.

First off the TC will not allow the camera to AF in " normal operation ", however try this ......

Put the camera in LIVE VIEW.

Then try auto focus.

I had a Canon 2X TC on my 7D with the 100-400 and in LIVE VIEW it would AF.

Mind you the AF was slow - but it did focus!!!!

.

Thanks for the quick reply guys..

Tom

You can also tape over the pins that report the extender, so the camera doesn't know you are using a max aperture of f/8, this will allow some sort of AF functionability. However, it may well hunt and be very slow unless you are in very good light.

Without using the tape trick, you will only have manual focus in normal use.

Sandpiper is right...the tape trick works. It will hunt a bit more so if it is something like an airplane going by, it is slow.