-=FAQ=- Teleconverter/T-Con Tele extender Discussion

gcogger wrote in post #4491991
Any of them will retain AF. None of them will allow you to shoot at f/4 - the laws of optics dictate that a 1.4x TC will lose you 1 stop. There are some TCs that don't let the camera know about the loss of 1 stop, but that doesn't mean that you haven't lost that stop.

Ok, so I guess I don't understand the benefit of a non-reporting TC. Does a non-reporting TC retain AF for all apertures where as a reporting TC only AF at some specific aperture (or not at all)?

Sumoto wrote in post #4497739
Ok, so I guess I don't understand the benefit of a non-reporting TC. Does a non-reporting TC retain AF for all apertures where as a reporting TC only AF at some specific aperture (or not at all)?

It's all about the camera. The 10 series bodies will not AF with any lens whose widest aperture is above f/5.6, and only when you add a TC.

For instance, the Bigma is f/6.3 at 500mm, but, it stiff autofocuses on the 30D.

A TC has a chip inside it that sends data to the camera to include in the EXIF, and to tell the camera what to do like AF or not. If you have a 400mm f/5.6 Prime, then add a 1.4x TC that reports, then the lens will not AF. If you add a non-reporting TC, it will AF, cause there are some pins missing, and it's my opinion, the chip inside is designed to hide itself, it doesn't pass any info, or, there is no chip inside at all, just like a Kenko tube.

But yes, a non-reporting TC, like my Kenko 1.5, will still AF at all apertures, and, in the case of my 300/4 Prime, it will show f/4, when it should show f/5.6.

I understand now, thank you!

canonloader wrote in post #4497850
A TC has a chip inside it that sends data to the camera to include in the EXIF, and to tell the camera what to do like AF or not. If you have a 400mm f/5.6 Prime, then add a 1.4x TC that reports, then the lens will not AF. If you add a non-reporting TC, it will AF, cause there are some pins missing, and it's my opinion, the chip inside is designed to hide itself, it doesn't pass any info, or, there is no chip inside at all, just like a Kenko tube.

But yes, a non-reporting TC, like my Kenko 1.5, will still AF at all apertures, and, in the case of my 300/4 Prime, it will show f/4, when it should show f/5.6.

SOME Kenko's have the chip and are reporting; others do not have the chip and are non-reporting. The 1.4x DG and 2.0 DG both have the chip; the 1.5x does not have the chip.

canonloader wrote in post #4497850
It's all about the camera. The 10 series bodies will not AF with any lens whose widest aperture is above f/5.6, and only when you add a TC.

For instance, the Bigma is f/6.3 at 500mm, but, it stiff autofocuses on the 30D.

A TC has a chip inside it that sends data to the camera to include in the EXIF, and to tell the camera what to do like AF or not. If you have a 400mm f/5.6 Prime, then add a 1.4x TC that reports, then the lens will not AF. If you add a non-reporting TC, it will AF, cause there are some pins missing, and it's my opinion, the chip inside is designed to hide itself, it doesn't pass any info, or, there is no chip inside at all, just like a Kenko tube.

But yes, a non-reporting TC, like my Kenko 1.5, will still AF at all apertures, and, in the case of my 300/4 Prime, it will show f/4, when it should show f/5.6.

I'm afraid I disagree. Let's have a look to theCanon's TC 1.4X II and TC 2X II parts diagram. You will see no chips inside. The TC are completely passive (no electronics inside), only glass, metal and wires.

If you see the parts catalog of the old version TCs (here is the TC 1.4X andhere is the TC 2X) you will find the wiring diagram. You may see that the bottom left connections (the three reporting pins) are different.
The diagram of the Lifesize Converter for the 50mm f/2.5 is here but under a wrong name. The wiring diagram is in the page 12.

It is the lens the one wich has to detect the TC.
When the lens detects a 2X TC then
It announces itself as a different lens (a 70-200/2.8 reports itself as a 140-400/5.6)
It can change the table used for the AF algorithm.

BTW, I see you still haven't found those diagrams. They are very interesting. You can see another files in the same directory. Some of them are parts catalogs, but there are some big PDFs, specially of old lenses, wich are also repair instructions. The one above of Lifesize Converter for the 50mm f/2.5 is a repair manual.

Your right, but the lens has a chip in it, that then reports back to the camera. In the case of the Kenko 1.5, it's missing 3 pins, the same ones everyone has been taping, that I guess, would send that data on to the camera. I guessed at a chip in the TC also, because I notice the missing pins of the Kenko 1.5 allow the camera and lens to AF fine, while taping the pins on the Canon 1.4X never did give acceptible results. I thought there was a chip there, but if not, it doesn't matter, the one in the lens can't report to the camera through a non-reporter.

And that's what counts.

canonloader wrote in post #4498988
Your right, but the lens has a chip in it, that then reports back to the camera.

That's right. An then the camera is the one wich takes the decission about to try the AF or to rely to MF. If it is a 1D or 1Ds (i'm not sure if the 5D qualifies also here) then it will try to AF when the reported aperture is between f/1 and f/8. Otherwise it will try to AF when the reported aperture is between f/1 and f/5.6

canonloader wrote in post #4498988
In the case of the Kenko 1.5, it's missing 3 pins, the same ones everyone has been taping, that I guess, would send that data on to the camera. I guessed at a chip in the TC also, because I notice the missing pins of the Kenko 1.5 allow the camera and lens to AF fine, while taping the pins on the Canon 1.4X never did give acceptible results. I thought there was a chip there, but if not, it doesn't matter, the one in the lens can't report to the camera through a non-reporter.

The electronics of a Kenko 1.5 are the same of a Canon 1.4X with the pins taped. You are telling me that the Kenko 1.5X gets proper AF when the Canon 1.4X doesn't. It is a bit odd behaviour.
Please, may you give us more information? I'm still learning. It would be fine if you tell us the lens and the camera and if you describe the way the AF behaves.

Katzer1 wrote in post #4495608
I'd like to share my experience with Sigma EX tc 1.4 + Sigma 150 Macro.
Unless pins are tapped, the lens will switch off AF if the subject is at less than 40cm. AF will resume only if the focus ring is manually turned beyond that distance.
The only place this (disturbing) behavior is documented that I found was a printed Sigma catalog.
Needless to say I have the pins taped on my tc....


Question: Has anyone ever tried the Sigma 150 with a kenko or tamron tc (I heard that on Nikon AF hunts a lot)?
Thanks
Erez
p.s
CyberDyneSystems, might worth an update to the first posts? I doubt folks who wonder about his would find this post

It is the expected behaviour. When a macro lens begins to work in a macro range then the aperture falls (see below *), the real f/number is worse than f/2.8 and if you put a 2XTC then it will be worse than f/5.6 and the camera stops AF.

Why Canon limites AF operation to f/5.6? To get a more controlled AF and less hunting.

If you put a non-reporting TC then you will reach a zone where you are telling the camera "hi, there is a f/5.6 lens and you should be able to focus with it" and though it is false, the camera can acheive AF.
After this you will reach another zone where you are telling the same, but the camera can't focus in this zone because no light reaches the AF sensors. Then the camera will try to AF, hunting a number of times and after this it will stop trying AF.

Here * Your Sigma 150mm f/2.8 is equivalent to a variable length tube (150 to 300mm) with a 6.66666 diopter lens (1m / 0.150m = 6.66666 diopter) on top. Let's talk about the lens wide open, because the AF calculations are performed wide open. The 6.66666 diopter lens is 53.57mm diameter (150mm/2.8=53.57mm).
When you focus to infinity then the tube has a length of 150mm. Then the aperture is 150mm/53.57mm=2.8
When you focus at 1:1 then the tube has a length of 300mm. Then the aperture is 300mm/53.57mm=5.6 (note the aperture depends on the length of the tube, not on the focal length of the lens). If you put a 1.4X TC on the lens you will get f/8.

That's what I am saying. And believe me, I am as surprised as anyone, cause I have owned the Canon 1.4 and 2x II TC's and never got any decent shots with them. Taping the pins just made it hunt madly, and that was with the Canon 100-400LIS and the Canon 400/5.6L on a 30D. With the Kenko 1.5x, it snaps to focus like there was no TC on it at all.

That's why I got the idea there was a chip in the Canon TC's and even though the pins were taped, the chip was still getting confused. If it has no chip, then the mystery is in why all the hunting with taped pins when a TC with only 8 pins on both sides instead of 8 and 11, works fine.

canonloader wrote in post #4502667
... I have owned the Canon 1.4 and 2x II TC's and never got any decent shots with them. Taping the pins just made it hunt madly, and that was with the Canon 100-400LIS and the Canon 400/5.6L on a 30D. With the Kenko 1.5x, it snaps to focus like there was no TC on it at all.

Canon states that on a 30D you can't put a TC to a f/5.6 and keep AF.
We are trespassing the Canon's rules when we tap the pins.

Hunt madly...is around the focusing point but never acheiving focus or from the infinity to the MFD and back to infinity? Please, I may have the same problem so I need to know it.

canonloader wrote in post #4502667
That's why I got the idea there was a chip in the Canon TC's and even though the pins were taped, the chip was still getting confused. If it has no chip, then the mystery is in why all the hunting with taped pins when a TC with only 8 pins on both sides instead of 8 and 11, works fine.

I don't know about optical engineering but I have some background in doingsurgery with TCs. Please have a look to the post where I tell you how to change the power of a TC.

When you move the optical elements of a TC closer to the lens it happens that:

1. The TC multiplies by a bigger factor.
   
2. You lose more light lose and surely more resolution.
   
3. You have to put a spacer (maybe a macro stepping ring) to get infinity focus.
   
4. The focusing scale is "compressed": turning the focusing ring very slightly changes the focusing distance from very close to infinity (or more than infinity) so it is very difficult to focus. This is interesting for our problem.

Actually, it does both. Goes from MFD to MFD in low light, in strong light, it get's close, overshoots, comes back, overshoots, comes back in ever decreasing amounts, and then just chatters back and forth. This kind of thing is not good for lenses and I tell people never tape the pins.

None of that happens with the Kenko 1.5, except in really low light, it wil go from end to end, then I just stop trying.

canonloader wrote in post #4504598
Actually, it does both. Goes from MFD to MFD in low light, in strong light, it get's close, overshoots, comes back, overshoots, comes back in ever decreasing amounts, and then just chatters back and forth. This kind of thing is not good for lenses and I tell people never tape the pins.

None of that happens with the Kenko 1.5, except in really low light, it wil go from end to end, then I just stop trying.

I red a post where it told that it was possible to burn the AF motor doing thisl. I hope it will be a fke message only trying to make you feel afraid.
Anyway, if it hunts then it is not focusing. We are not trying to do a scholar dissection of a TC, we want to make a photo so we want perfect and fast focusing.

ok after reading this from front to back i am totally confused. some say it will work some say not. can anybody please tell me if it will work and which one with a 400d with the 70-300 IS usm f/ 4-5.6. thanks for any help you can provide.

I use the Kenko 1.4x with the 400D and Canon 70-300 IS and it works, no problem, autofocus works fine.

Seriously, I am sure if you did read this front to back you would have read at least one of the many times where I have repeated that THERE IS NO GUARANTEE that trying to FORCE a camera to function out of spec will actually work to your expectations.

There is no guarantee.

In fact the odds are against it.
There are too many variables involved, having to do with the lighting at the time you try it, to your speific copy of a lens and body.
If it woprks for one person in one situation is no guarantee it will ever work for you with your equipment and your shooting situations.

So you get the choice:

1. Listen to what the faq says and be 100% guaranteed of results.

2. Try something different with tape or a non reporting TC used out of spec and take the gamble that you will get no AF, bad AF, or decent AF, or worst of all, if you don't pay attention to what your equipment is telling you, actually break something.

To your specific needs, as the FAQ says, your lens will not AF or even fit a Canon TC or a Sigma TC.

There are several TCs that will physically fit, but NONE can guarantee AF. The lens and Body are not designed to AF with any TC.