Canon 2X &1.4XTCIII stacking?

[Jack Faller]

I recently upgraded to TCIII's and the performance is an improvement. I successfully used the TCII's stacked, but the III's won't stack. It appears like the inner diameter of the 2X III is a bit smaller. Not anxious to push too hard.

Has anyone else run into this problem? Is there an easy fix?

[Doug Brown]

You may be able to put an extension tube in between the 2 TCs.

[Steven Kersting]

Have you tried reversing the order? I can add my 1.4 behind the 2x, but not in front of it. (Nikon)

[Fred J. Lord]

Maximum focus distance dropped to just under 40 feet. So, if your subject is within that distance, you're okay.

[John Chardine]

Hi Jack- Canon does not support stacking the TCs but it's possible as long as you insert an extension tube (12mm) between them. The order of TCs does not seem to matter and you can focus on infinity.

[Jack Faller]

Have you tried reversing the order? I can add my 1.4 behind the 2x, but not in front of it. (Nikon)

yes, Doesn't work either way with the III's

[Charles Glatzer]

FYI- You all may find this of intertest regarding the new converters and there use with the new telephotos and the new 70-200 f/2.8IS II

From Canon...

"To achieve the maximum benefits of this new processor, you need to ensure that you attach the lens to the Extender first, and then attach the whole lens and extender combination to the camera. This way the camera will see a combined "Lens + Extender". If you add the extender to the camera first the camera will recognise it, but will the newnot be able to deduce that a lens has been added to the front of it."


Best,

Chas

[Jack Faller]

Hi Jack- Canon does not support stacking the TCs but it's possible as long as you insert an extension tube (12mm) between them. The order of TCs does not seem to matter and you can focus on infinity.

Thanks for the tip. It works great with 2X:12mmext:1.4X:camera. and this combo allows manual focus at >several 100 yards.

[Charles Glatzer]

Thanks for the tip. It works great with 2X:12mmext:1.4X:camera. and this combo allows manual focus at >several 100 yards.

Jack,

I would not stack except after shooting the subject with only one converter. Almost always a sharper image will result from cropping than stacking.

1-shooting any subject at several hundered yards will more than likely not be rendered very sharp due to atmospheric problems.
2-stacking increases magnification and further enhances any flaws in Stabilization technique.
3-stacking requires a smaller aperture, resulting in higher ISO to maintain faster shutter speeds.
4- usually requires stationary subjects and manual focus
5- at f/16 you will start to see diffraction problems with most cameras

This being said... I have produced very sharp images w/ a 400 f/ 2.8 and stacked converters at f11, but rest assured this is not the norm, and it is only done after I have taken the best image possible w/ a 2x alone. And, always after stopping down at least an additional stop off wide open. Meaning a f/4 lens with 2x and 1.4x should only be taken at f/16 or smaller f/stop.

Sharp? I am not going there again-lol

Warm Regards,

Chas

[Jack Faller]

Chas,

I agree with you on all points.
1. Fred said that he was stuck with a maximum focus at 40 ft; it seems like you can focus at infinity ( per John), but would probably want to operate at less than 100 yards owing to heat shimmer.

4. with my 7D, I have to manually focus with either 2.0x or the stacked combo.
the depth of field with the stacked setup is also really small, so focusing accuracy is really a problem.

In order to get the best focus I use the quick view settings that allow you to observe the image on the sensor and magnify it. This allows focusing at 5x or 10x. At that magnification, it is impressive how much vibration there is, even on a locked down tripod.

The sharper image obtained from cropping is definitely worth it, relative to stacking.
The following test compares images taken at ~30 yards and cropped to approximately the same size.

jack