Extender 2x & f4 lens & 5D mk2

Started Jan 1, 2011 | Discussions
Ian Boulton Regular Member • Posts: 205
Extender 2x & f4 lens & 5D mk2

After many searches on DPR and on the internet, I am struggling to get a clear answer to the following question.

Will the autofocus still work on the following combination?

Body: Canon 5D Mk2
Lens: Canon EF 70-200mm f/4L IS USM
Extender: Canon 2x mkII or 2x mk III

The Canon web sites say it is compatible, and in the Canon EF Lens catalog it clearly states that the AF works.

However, on DPR there are a number of posts saying that only the 1 series cameras will focus at f8 (which the f4 lens will effectively become) and so the AF will not work on the 5D/f4/2x combination. Also, some posts say that only the centre focusing point will work in AF (this is not a problem for me).

Could someone give me some clear guidance or point me in the right direction for a clear answer.

My problem is that as I now live in India, the shops do not have the extender in stock so I have to "Buy before you try" rather than "Try before you buy". So I cannot go down to the local shop and try it out for myself.

Thanks in advance for any help


 Ian Boulton's gear list:Ian Boulton's gear list
Panasonic Lumix DMC-TS4 Canon EOS 5D Mark II Canon EOS 10D Canon EF 50mm F1.8 II Canon EF 17-40mm f/4.0L USM +5 more
dddiver Regular Member • Posts: 379
Re: Extender 2x & f4 lens & 5D mk2

Hi Ian,

You already gave the answer: No, AF will not work because 5Dmk2 needs f 5.6 to AF. The manual of the camera clearly says so.
You have 2 options left:
1. "taping the pins", which will result in slow and unreliable AF
2. buy a non-reporting (i.e. non canon) extender/converter.

Canon states that the extender is compatible with a number of lenses which is correct, but AF will only work with compatible camera's.

Good luck,


RS_RS Senior Member • Posts: 1,788
Re: Extender 2x & f4 lens & 5D mk2

Phase-detect AF on the 5DII body switches off on any lens recognised by the camera as having a narrower aperture than f/5.6. The 70~200/4 + Extender 2× combination is recognised as an f/8 lens so phase-detect AF is not possible. On 1-series bodies, and at the central focus point only, the cutoff is at f/8 rather than f/5.6, so phase-detect AF with this combination is possible.

There are two different workrounds. One is to use Live View and contrast-detect AF, which is not aperture-limited but is slow, and may not lock on in low-light low-contrast situations, although if you can get contrast-detect AF to work, it is accurate, with none of the calibration issues that may need to be adjusted for with phase-detect AF.

The other workround is to fool the camers into failing to realise that this is an f/8 combination, either by taping the extra pins between the Extender and the lens, or by using an off-brand "non-reporting" TC without the capability to signal its presence to the lens, and without the internal electronics to do the job an alternative way. This may not work reliably; the cutoff beyond f/5.6 isn't just to irritate users.

OP Ian Boulton Regular Member • Posts: 205
Re: Extender 2x & f4 lens & 5D mk2

Thanks to you both for your prompt replies.

It seems pretty clear now, especially after re-reading both the manual and the lens catalogs, that AF will not function with the 2x converter / f4 lens combination.

Canon could add a note on the lens catalog to make it clearer that when it says that autofocus is possible with the 70-200 f4 lens mounted on a 2x extender, that it only applies to series 1 bodies.

Once again DPR comes to the rescue, and so I will have to search out an alternative.

I am not sure about taping up the contacts and I will need to investigate a non Canon extender, not easy in India.

By the way, the reason this question came about is because I have just moved to India in August 2010 (Last year already !!!). My wife and I went to a wild life sanctuary over Christmas and caught the bug for nature photography. I would love to get closer shots as the wildlife is quite a way off. The 21 MP and Lightroom help to get some good shots (see attached) but I would love to find a solution for a longer lens that does not cost the earth - 400 mm and f2.8

Anyway, thanks very much for your invaluable help


 Ian Boulton's gear list:Ian Boulton's gear list
Panasonic Lumix DMC-TS4 Canon EOS 5D Mark II Canon EOS 10D Canon EF 50mm F1.8 II Canon EF 17-40mm f/4.0L USM +5 more
QuaziSanjeed Junior Member • Posts: 39
Re: Extender 2x & f4 lens & 5D mk2

Well, I opted for the easiest solution to this issue - manual focusing. I use a 2x Canon extender with my EF 400mm f/5.6L USM to make it 800mm on my 5D II. The aperture shoots to f/11. However, in good light I get pretty decent pictures of static subjects while focusing manually.

Attached is an image shot on 16Mar2019 taken with this combo applying the MF option.

Obviously it's difficult to use the same combo for mobile subjects or in poor light.

So far I know, Canon EOS 5D IV will AF on f/4 lenses paired with the 2x extender.

Yellow-wattled Lapwing.

 QuaziSanjeed's gear list:QuaziSanjeed's gear list
Canon EOS 5D Mark II Canon EOS 7D Canon EOS-1D Mark IV Canon EF 400mm f/5.6L USM Canon EF 17-40mm f/4.0L USM +1 more
John Crowe
John Crowe Senior Member • Posts: 2,295
Re: Extender 2x & f4 lens & 5D mk2

On the 5DII the AF with a third party extender and an f4 lens is not likely going to be successful for birds in flight.  For perched bird shots I would stick with simply using your f4 lens in manual mode, with no taping required.

Taping the 3 pins is extremely easy to do and not detrimental in anyway.  I would try that before buying a third party extender because it will likely get you very similar AF performance.  A third party extender does not provide as good image quality as the Canon ones.

 John Crowe's gear list:John Crowe's gear list
Canon EOS 5DS R Canon EF 70-200mm F4L USM Canon TS-E 17mm f/4L Kenko Teleplus Pro 300 AF 1.4x Venus Laowa 12mm F2.8 Zero-D +15 more
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