It appears that the Series III Extenders are an optical improvement over the Series II Extenders when it comes to older lenses.
But my question now is can it be stacked with 3rd party teleconverters from Kenko & Tamron. This isn't a major problem but I want to know my flexibility if ever I upgrade.
Ian.Dobinson wrote:
they dont look any different in design over the previous ones. But cant you stack a 3rd party TC behind the Canon one?
I am told that the Series II Extenders does stack with 3rd party teleconverters though I talked to one photog who said it doesn't take stacking. So I had to ask here to the Oracles of FM. ;-)
The type 3 2x TC does stack just fine with non-canon TC's. Tested it with tamron 1.4's and Sigma 2x.
The type3 does not stack with the Canon 1.4x TC type2. I didn't have a 1.4 type3 to check it with, but I understand the type3's do not stack together like the type2's will.
OK, here's what I know so far (the Mk III 2X just arrived this evening):
You can stack the 1.4X or 2X III behind the 2X II. You cannot stack either the 1.4X II or the 2X II behind the 2X III. The opening in the back of the Mk III is just a little smaller in diameter and not quite as deep as the Mk II. I did not try forcing things - I'll leave that up to someone that has a few teleconverters to spare.
If you have a third-party teleconverter that does not have a protruding element in the front, you can stack it behind almost anything including the Mk II and many other lenses that normally don't accept a teleconverter.
BTW, preliminary tests - the Mk III on the 135/2 wide open is noticeably sharper in the center than the Mk II. This is under incandescent lighting. It was getting dark by the time UPS showed up today.
I haven't done any serious testing and comparison shots yet so I can't say much more.
Tom_W wrote:
OK, here's what I know so far (the Mk III 2X just arrived this evening):
You can stack the 1.4X or 2X III behind the 2X II. You cannot stack either the 1.4X II or the 2X II behind the 2X III. The opening in the back of the Mk III is just a little smaller in diameter and not quite as deep as the Mk II. I did not try forcing things - I'll leave that up to someone that has a few teleconverters to spare.
If you have a third-party teleconverter that does not have a protruding element in the front, you can stack it behind almost anything including the Mk II and many other lenses that normally don't accept a teleconverter....Show more →
That is interesting. I thought that the Series II and Series III cannot be stacked together and that only 3rd party teleconverts can be used.
I may end up not selling my Series II Extenders if this is the case.
dolina wrote:
That is interesting. I thought that the Series II and Series III cannot be stacked together and that only 3rd party teleconverts can be used.
I may end up not selling my Series II Extenders if this is the case.
Well, the new series 3 will stack with the series II 2X only if the Mk III is behind the Mk II. The 2X Mk II will accept the protrusion of another teleconverter, but the Mk III 2X will not.
Prior to owning the 7D, I had occasionally stacked the 1.4X and 2X Mk II teleconverters together. The 1.4X has to go behind the 2X because only the 2X Mk II teleconverter can accept the protruding element of another teleconverter. Anyway, the combination worked well on the 5D and 5D2, and even allowed autofocus because the AF system didn't recognize that there were 2 teleconverters and thus thought I had an f/5.6 lens instead of f/8.
This all changed with the 7D. The high pixel density showed the weakness of the stack, so that using the 2X alone produced an image that was equal to or better than a downsized stack image. The situation was hampered by the fact that I had to stop down to f/13 or smaller to get the best results, but the 7D was able to show diffraction at that aperture.
