1.4x & 2x Teleconverters Stacked / 2.8x extender Mark II & III

I occasionally stack my TCs on my 300 2.8 L. The problem with this is that it only reports the 2x one. That means I can not set different micro adjustments, and my exif data is wrong. Having the exif data correct would be nice to help me know which pictures came from which setup. I try to tag them 2.8x in processing, but sometimes can't remember. Plus I would just like the exif data to be correct. And would benefit from the added micro adjustment.

So, Is there anyway to get stacked TCs to report? Do any other brands worth using report. what about the newer Mark III versions?

Is there a 2.8x extender out there? I read about a rumored one once but never seen one.

Any other helpful thoughts?

Thanks!
-Matt

I can only answer one of your questions.......the new 2x and 1.4x vIII extenders are not stackable, fit-wise. I sure wish they were.

I've seen some 3x TCs a few years ago...can't remember the manufacturer. I think it was a "cheap" brand, and had heard that the IQ sucks! 3x would be no good though, would "just" put you over the f/8 AF limit.

mjHession wrote in post #16197027
So, Is there anyway to get stacked TCs to report? Do any other brands worth using report. what about the newer Mark III versions?

Only the TC connected directly to the lens can report. The teleconverter just passes through the main signals. The extra three contacts between the TC and the lens tell the lens that a TC is attached and if it is 1.4x, 2x, or a life size converter. The lens then slows its focus some depending on if it is 1.4x or 2x and updates the EXIF data sent back to the camera. There is no provision to indicate a second teleconverter.

The camera knows about the teleconverter only because the main lens has reported it and it can only know about one. The Canon protocol uses two of the extra pins to indicate and can only indicate none, 1.4x, 2x, or LS converter. You would have to keep track yourself of the dual TC use.

1Tanker wrote in post #16197148
I've seen some 3x TCs a few years ago...can't remember the manufacturer. I think it was a "cheap" brand, and had heard that the IQ sucks! 3x would be no good though, would "just" put you over the f/8 AF limit.

I've seen a Kenko 3x, but from what I have read it does not report, which doesnt really solve my problem. It would only be worth it if the optics were better than Canon's Stacked, which I doubt it is.

The Sigma TC's are the same way, when you stack them. Since I have a 7D, it works out ok for me.
But I do need a lot of light for the autofocus to still work with both my Sigma 120-300 f/2.8 and the
Canon 70-200 f/2.8 IS II. I should try it with a small lazer pointer some time to see if it helps.

--Evan

I know from experience my x1.4 MkII and x2 MkIII will not stack. It's been suggested a work-around is interposing a 12mm extension tube between them.

Would I lose infinity focus in this scenario? ( I don't have my TCs and tubes to hand right now, so can't test). Anyone tried it?

I would love it if Canon came out with a high-quality 3XTC. My guess is something like their 300mm 2.8 IS II would survive ok IQ-wise as a 900mm f/8 lens.

It'd obviously be a "niche" product for those with full-frame bodies that AF to f/8, but I for one think it'd be a pretty cool product.

xhack wrote in post #16808973
I know from experience my x1.4 MkII and x2 MkIII will not stack. It's been suggested a work-around is interposing a 12mm extension tube between them.

Would I lose infinity focus in this scenario? ( I don't have my TCs and tubes to hand right now, so can't test). Anyone tried it?

Here is a blog post from a while back from Arthur Morris about this same thing: http://www.birdsasart-blog.com …elephoto-lenses-and-more/

You need to put the 1.4x on the body and the 2.0x on the lens with the 12mm tube in between to get infinity focus.

I've tried this and haven't been happy with the results even using the 300 f/2.8 IS II which should be the best lens made to even try such a feat. AF just doesn't work very well and the IQ takes a hit where I'd rather just use the 2xTC and crop.

The only success I've had with 1.4 and 2.0TCs is putting a 2.0TCIII on my 200-400 with the internal 1.4TC engaged to give a 1120 f/11 lens. The IQ of that combo holds up fairly well but then it is of course MF. However if you are shooting a static subject and have support you can AF without the internal TC engaged and then just flip it on and the focus doesn't shift so you don't have to MF.

Thank you for the link and the tip - I would instinctively have offered up the x2 to the body. Ignorance is bliss.

I have no great expectations, but it'll be interesting to see how the combo works on my 300 ƒ/4. You never know . . .