help with canon 2x III extender autofocus

[ptapaskar]

Hi 

I have a canon 100 400 IS II USM lens and have recently purchased a canon 2x III extender. 

I have a canon 6D mark II camera.

I need help/advice. on the following issues.

1. I cannot auto focus using the extender. In fact the autofocus option disappears once the lens and extender is mounted on the camera. 

2. The pictures are a bit hazy. 

3. Any other tips to take wildlife photos using the extender. 

Thank you. 

1. 

[MikeSowsun · Accepted solution]

Your 6D Mk II can only AF if the lens aperture is f/8 or larger. Your 2x extender doubles the aperture on your lens from f/5.6 to f11 and makes AF impossible

I would advise returning the 2x and buying a 1.4x extender which will result in a f/8 aperture and still allow AF with your camera and lens. 

Any extender or teleconverter will cause image degradation but the 1.4x extenders have less degradation than the 2x. Shooting stopped down at f/11 will help.

[ptapaskar]

Thanks for the reply. I will exchange for a  1.4 x extender. 

[ptapaskar]

Many thanks Mike.

[ebiggs1]

Always read the compatibility list before you buy a tel-con. The 2x is a bad idea even on lenses it is compatible with. IMHO, of course.

[ptapaskar]

Thanks for your advise. This lens was in the canon compatibility chart for the extender. 

Need to go for 1.4 x I guess. 

[ebiggs1]

"Any other tips to take wildlife photos using the extender."

One of the 150-600mm super zooms. They are the best bang for the buck in a big wildlife tele. If 600mm isn't enough FL you need to get closer to your subjects.

[ebiggs1]

"This lens was in the canon compatibility chart for the extender."

However, ....

The noted advice from Canon is, "Additionally, please see the lens and/or camera body manual for full compatibility information with the Extender EF 2X III."

Checking the 6D Mk II manual, I only see, the 1.4x III mentioned for the 100-400mm.

"EF 100–400mm f/4.5–5.6L IS II lens, with Extender EF 1.4x III."

[alexcphotos]

I have the same problem with that lens when shooting through the viewfinder, but what I found odd is that on my 1D-X MkII when I shoot using liveview / the backscreen, AF does work! Granted its slower to get there than the 1.4x III, but it is possible, at all focal lengths and the pictures come out sharp and in focus. I don't know how exactly the software in the camera is programmed, but if it can do it one way, why can't it the other? 🤔

[alexcphotos]

GIYF - found part of an answer in another thread:

"Be aware that the camera uses one AF system for when you use the viewfinder, and another AF system when you use Live View mode."

https://community.usa.canon.com/t5/EF-RF-Lenses/Canon-EF-100-400-f-4-5-6L-with-2x-extender/td-p/4107...