7D Mk II - overexposure with 2x TCs

Initially just canvassing opinion/putting it out there...

So far I've been delighted with my 7D Mk II - it improves over my 7D and 70D in every area that matters to me.

Except...

Whereas those cameras both work perfectly well with my Sigma 120-300mm f/2.8 and 70-200mm f/2.8 lenses, and 2x TCs (Sigma or Canon Mk II), my 7D mk II over-exposes by almost two stops with the same lens/TC combos.

Every time.

In any exposure mode.

1.4x TCs from Canon, Sigma and Kenko all work perfectly with my 7D Mk II and the Sigma lenses; but with either 2x, exposure is all to hell.

I can get round this easily enough by dialing in -1.75 EC, but it's a 100% repeatable problem, so presumably fixable via a firmware update, assuming that it's not a freaky by-product of the specific combinations of camera, lenses and TCs I'm using.

Anyone else seeing this?

Does it happen with Sigma lenses mounted on the converter only, or also with Canon lenses?

apersson850 wrote in post #17274986
Does it happen with Sigma lenses mounted on the converter only, or also with Canon lenses?

So far I've only been able to test with Sigmas - it'll be a week before I can put a suitable Canon (a 70-200mm f/2.8 II) on.

I just tried out my 70-200mm f2.8 II w/2x III extender and exposure looks normal.
Sounds like maybe Sigma needs to issue a firmware update perhaps.

One thing,which I'm sure you're aware of,is the order you mount the extender.Canon states you should first attach the extender to the lens,then attach both to the camera body.This is to insure proper communication between the lens and body.

I'm sure you already do this,but I mention it just to make sure.

Good luck finding a solution,

Robert

Thanks Robert, very helpful.

As you suggest, I've a feeling I might end up pushing this Sigma's way, and you've helped narrow things down.

Although I'm not sure that the connection order of the components matters as much for third party lenses and TCs (Canon's guidance here seems very specific to the Mk III TCs) I've borne it in mind anyway, but it hasn't made a difference, I'm afraid.

This isn't a show-stopper for me - I don't use 600mm that much really - and the -ve EC workaround works well enough.

Thanks again.

This could be a problem for me then as I use 2X extensively with my Sigma 120-300 for birds, so perhaps I should defer my 7D2 purchasing decision.

Nah, treat yourself to the new EF 100-400 mm f/4.5-5.6L IS II USM, and it's likely that any Sigma-related problems go away!

artyman wrote in post #17275185
This could be a problem for me then as I use 2X extensively with my Sigma 120-300 for birds, so perhaps I should defer my 7D2 purchasing decision.

As I suggest, it's manageable easily enough by dialing in some -ve EC, but it's a pain. In all other respects, the camera's brilliant.

And if it is something that Sigma needs to address, you're not really gaining anything by holding off on the camera.

Just tried my 7D2 plus 2x tc III with my Canon 300 2.8 II and my Canon 70-200 f/4 IS. I didn't have any exposure issues.

Regards, Jim

Thanks Jim - pretty clear it's a Siggy thing, then.

That said - both you and Robert have used the Mk III Canon 2x: I wonder if that's making a difference (mine is the Mk II)..?

somebody throw me a 7D2 quickly..., I'll test your problem
I have the same setup as you do Keith, minus the 7D2. I have no problem with it on my 70D.

Yeah, the lenses and TCs are fine on my 70D too, Gabe...

Nobody else shooting with a 7D Mk II, 2x TC and third party lenses, then?

I've had no problems with the 300f4 or the 500f4 II using the 2x III. Sorry, none of those are 3rd party, but as far as with those particular pieces of equipment, I've had no exposure issues.

Keith R wrote in post #17277253
Nobody else shooting with a 7D Mk II, 2x TC and third party lenses, then?

No, but I got this response from Sigma today when I asked about using a 50-500 IS and my sigma 1.4 teleconvertor :

Hello Jack,
No it will not, the converter will prevent it.
Yours Truly,
Paul Pizzano
The Sigma Corp. of America


I'm still trying to understand that...