2X converter

[DEG5Y]

After using a 1.4 Converter with my 100-400 zoom for a while I decided to go one step further and bought a 'like new' 2X converter.

For a very short period everything was OK but on a trip out I realised that I had lost the Auto Focus.

I had it replaced by the company I bought it from without question.
But on it's first trip out on to the Peak District moors the replacement has done the same.

It was more evident this time that because there was no AF, (I could focus manually), I had lost the Image Stabilisation.
A big problem when the subject is probaly 3/4 of a mile away.

Is this common or do I have something amiss?

Camera was being supported by a monopod secured to the lens.
I removed the converter and everything worked as it should.

[Farider]

The issue may be with your camera not being able to achieve autofocus because of the 2 stop loss you get from the 2X converter, the camera needs to be able to do F8 auto focus and not all do. There have been some excellent articles on this in the EOS mag, Richard might be able to point you to the issue they appeared in. It’s worth a check.

Ian

[DEG5Y]

So it could actually be technical issue.

Camera is a 5D mk IV

[Trev B]

Not dirty contacts is it - camera - converter - lens. I remember having problems once with a 1.4, cleaned all the contacts, problem solved, worth a try.

[@imagesBV]

Yes the long end the EF100-400 has a max aperture of f5.6…with 2x converter the combined aperture is 2 stops more so f11…the 5D4 is capable to f8. At the short 100mm end wide open at f4 the combination should work as a combined f8….if this doesn’t work then there maybe a hardware/firmware fault.

[DEG5Y]

I checked the contacts after the first converter played up.
When I first bought the first one, I did get some pics with it that I was really impressed with.
But they were taken on a really bight day which could have been the difference.

So it sounds like the EF100-400 and the 2x converter are not a perfect combination.

[El Sid]

Canon extender or 3rd party accessory? Third party converters can be a bit erratic, sometimes they will try to focus and succeed and sometimes they won't... I have two Kenko 2x models, one will happily focus with my 70-200f 4L - even my ancient D30 - while the other simply does nothing...

As far as I can recall the 100-400L is not suited to 2x converters.

[DEG5Y]

Canon extender or 3rd party accessory?

Canon 2X MK II

As far as I can recall the 100-400L is not suited to 2x converters.

This seems to be what I am now finding out!


If anyone knows which edition of the mag it was covered in, it would be good to get hold of it and have a read.

[Robert Scott]

EF 100-400mm f4.5-5.6L IS II USM was featured in the January-March 2015 issue, page 24.

As. mentioned earlier in this thread, the maximum aperture at 400mm is f5.6, which becomes f11 with a 2x Extender. Your camera will not provide viewfinder autofocus at an effective maximum aperture of f11. You might manage to autofocus at 100mm with the 2x Extender, but this is pointless as this will only offer an effective focal length of 200mm, which you can obtain with the lens without an Extender.

You might find you can autofocus at a maximum aperture of f11 with the EOS 5D Mark IV when using Live View. This is not specified by Canon, but seemed to work in our tests. See article 'Autofocus at f11', January-March 2021 issue, pages 56 to 59.

[DEG5Y]

Thanks for that, I have the 2021 issue but hadn't read it thoroughly as at the time didn't have the 2x Extender.

Reading the article, there can't be that many lenses that it would work with properly.