Telephoto for Canon EOS 760D

Hi all! It's my first post here and it's because a bit of a crisis.

My partner has a Canon EOS 760D, and she recently decided to buy a lens to come birding with me. She didn't want anything too bulky to be able to take it hiking, so she bough a Canon 100-400mm f4.5-5.6 L IS USM. Now, the lens works great, but as the reach is a bit short for some things she also bought a 2x Canon teleconverter.

The problem is, the AF doesn't work with both. Looking into the documentation of the lens, it turns out that this lens+teleconverter combination only allows to autofocus in very specific cameras (such as the EOS-1Ds line, and EOS 10D to 40D). According to the documentation, the 1.4x teleconverter should have the same problem, although since it has a smaller impact on the f stops we are not sure. She really wants that extra reach and the AF for birding, so what are her options now? Is there any other lens that is compatible with this camera+teleconverter (either 2x or 1.4x)?

Alternatively, she is open to changing the camera body if there is a reasonably priced sidegrade or upgrade, but the 40D is a downgrade. The documentation doesn't say whether it would work with a 70D for example, but it might be because the lens is too old, should that camera autofocus with the canon 100-400+2x teleconverter?

She is still in time to return both the lens and teleconverter, so we want to find out what the best option is to have that extra reach while there's time to return them.

Thank you very much in advance!

AntonVA wrote:

The problem is, the AF doesn't work with both.

Anton,I did a little poking around, and a lot of people seem to have trouble with the autofocus on a 2X teleconverter for Canon EOS cameras.

Most people seem to recommend manual focusing. Here's some examples:

From stackexchange:

Canon DSLR bodies prevent poor auto-focus performance by disabling it completely when the lens reports maximum aperture at chosen focal length smaller than f/5.6. This implies that some lenses will not auto-focus on a teleconverter, e.g. the popular Canon EF 100-400 f/4.5-5.6L, or any f/4 lens on a TC stronger than 1.4×.

This was posted on an Amazon site:

Canon EOS & Rebel Series 2X Teleconverter for EF & EF-S Lenses

“I bought this because I had been looking into converters for a while and the one I really wanted was out of stock everywhere. This one had good questions and answers on it, so decided I would try it and hope it was what I was looking for. I really like this converter! I'm using it with a Canon 5D Mark iv and have used it on a 25-75mm, 75-300mm, and 400mm. Once in a while I can get it to auto focus, but 95% of the time, I have to manually do it, which is fine, just takes more time and a lot more precision as I tend to photograph wildlife. Keep in mind too, you will need to fix all of your manual settings whenever you put a different lens on, a lot of times I keep mine on auto because I'm out during the day, but shooting a variety of fast moving animals. Don't use auto anything with this converter, use manual all the way”.

2X Teleconverter Compatible with Canon EOS Rebel T2, T3, T4, T5, T6, T7, T8, T2i, T3i, T4i, T5i, T6i, T7i, T8i

Amazon site:

“I may change my review at a later date but for now I’ll point out that it’s advertised as Canon but when I received it, it is Vivitar. No cleaning cloth came with it. It is supposed to work with autofocus but it does not find the proper focus unless you try several times. If in autofocus the shutter doesn’t always respond. It does seem to respond in manual mode.”

Steve Thomas

Hi,
you are probably aware you loose 2 EV with the 2x converter, it means at the long end of 100-400 you are at f/11 minimum.

It is no good for AF with enthusiast cameras , but worse, as to my humble experience , you don’t achieve shutter speed short enough for BIF, regardless of camera.

Feel free to correct me, anyone

Just My 2 cents , 2x converter is no way to go.