kenko "pro 300 DG" 1.4 TC won't AF with:

my 7D or 5D with my 100-400? It WILL AF with my 10-22 though? Those are the only 2 lenses I've tried, but is there a reason it won't, or should I look into an issue with my 100-400? Contacts maybe? It's supposed to be a "non reporting" TC so the camera should at least try to AF right? I get NOTHING... But the IS does kick in when I hit the (rear) focus button?

Hi Ben,

The 100-400L only AFs with 1D range bodies when a reporting converter is mounted. It's the infamous F/5.6 vs F/8 problem. It'll become a 140-560 F/6.3-F/8, whereas the 10-22 becomes an 14-31 F/5-F6.3, which is borderline.

You could tape the leftmost three pin contacts on the converter (any isolating tape will do). It should work in that case, but AF is likely to be slow, and the converter will not be reported in exif.

HTH, kidn regards, Wim

it's a non reporting TC though...

it doesn't even have those pins...

edit, looking at B&H's page, maybe it does, I'll check tonight:

jacobsen1 wrote in post #10944569
it's a non reporting TC though...

it doesn't even have those pins...

edit, looking at B&H's page, maybe it does, I'll check tonight:

The Pro DG is indeed a reporting teleconvertor, and the fact that the photo shows 11 pins (group of 8, group of 3) is proof of that characteristic of this illustrated teleconvertor.

When the lens lacks the additional three pins (5-pin group rather than the 8-pin group, it does not trigger the body to recognize that the teleconvertor is slowing its max aperture, and the body still thinks it is the original aperture. That is why the WA lens works fine with AF, while the 100-400 refuses to try to AF.

Taping pins merely FOOLS the body into trying, but that does not mean that it will be SUCCESSFUL in the attempt to AF.

well, it's not reporting when I'm using it on my 5D and 10-22.

but apparently the camera DOES see the aperture conversion.

I was under the impression it was non reporting, but as we both said, that many pins means it is so tape should fix the issue.

jacobsen1 wrote in post #10944647
well, it's not reporting when I'm using it on my 5D and 10-22.

but apparently the camera DOES see the aperture conversion.

I was under the impression it was non reporting, but as we both said, that many pins means it is so tape should fix the issue.

The body sees less light coming thru the lens (its actual aperture size truly is smaller because the FL is now longer), but the body does not realize that the reported aperture is wrongly reported, that what was f/4 is truly f/5.6 with the convertor in place.

As I said above, when the lens lacks the additional three pins (5-pin group rather than the 8-pin group, it does not trigger the body to recognize that the teleconvertor is slowing its max aperture, and the body still thinks it is the original reported aperture. That is why the WA lens works fine with AF, while the 100-400 refuses to try to AF.

Yep, it is a reporting converter. I guess the 10-22 doesn't have the wiring to report it, as Canon probably didn't ever think anybody woudl want to use a converter with it .

After all, its full name is a tele-converter .

Kind regards, Wim

I have the Kenko DG, and I have tried it with a 5-pin group lens (100mm f/2, Tamron 28-75mm f/2.8 ) and with an 8-pin group lens (70-200mm f/4 IS) and it behaves exactly as I stated...the presence of the teleconvertor only happens with the 8-pin group lens.

wimg wrote in post #10944701
After all, its full name is a tele-converter .

good point,, never thought of that.

jacobsen1 wrote in post #10944569
it's a non reporting TC though...

it doesn't even have those pins...

edit, looking at B&H's page, maybe it does, I'll check tonight:

So, in this photo, which 3 pins get the tape? The ones on the left or the ones on the right? I know someone above said on the left, but it depends on which side of the converter you are looking at.

The outer 3 on the larger group

jacobsen1 wrote in post #10944647
well, it's not reporting when I'm using it on my 5D and 10-22.

but apparently the camera DOES see the aperture conversion.

I was under the impression it was non reporting, but as we both said, that many pins means it is so tape should fix the issue.

i think that's because the 10-22mm doesn't have contacts where those 3 pins are on the end...

NeutronBoy wrote in post #10945523
So, in this photo, which 3 pins get the tape? The ones on the left or the ones on the right? I know someone above said on the left, but it depends on which side of the converter you are looking at.

I specifically mentioned the pins, so indeed, the left three pins you see in the image .

Kind regards, Wim