1.4x MKIII Teleconverter

[JoeKerslake]

I am looking at couple a 70-200mm f/2.8L II IS USM with a 1.4x MKIII teleconverter.
Has any use both of these together, worried about a significant loss of AF speed and IQ, the latter being the bigger of the worry.

Thoughts?

 

[nc0b]

I still have the 1.4X TC III, and it is quite useful with both the f/2.8 IS II and the f/4 IS zooms. Focusing speed is modestly slower, but the extra reach, if needed, is worth the compromise. I sold my 2X TC III since the focus speed was significantly slower, and more to the point, for BIF, it would get lost in the sky and never recover focus. I now have the 300mm f/4 IS and the 400mm f/5.6 and never used the 2X any more. I did do some controlled sharpness tests comparing the f/2.8 IS II zoom with the 2X against the 400mm f/5.6 at 30 feet, mainly center image IQ. There was more variation from shot to shot auto focus (5 shots each) than there was difference in the IQ between the pair. If the zoom focal length range with the TC attached makes sense for a given shoot, consider it an real advantage to have that option in you camera bag. It weighs next to nothing, and you will be pleased with the IQ of the combination. If I am able to carry a crop and a FF body with me, I would choose that first, but of course you can also use the TC with the zoom on a crop. I get best results with BIF with my 6D and the 400mm, but for other wildlife that are not moving
so fast, and framed against the sky, both the 2X and the 1.4X TC IIIs were useful.

 

[Mt Spokane Photography]

I have the combo, but prefer my 100-400mm L MK II to putting a TC on the 70-200. However, if you do this only occasionally, it works fine, and the image quality is very good. AF speed depends on the camera as well as the lens, the 1 series cameras focus faster due to the higher battery voltage driving the AF motor. Any time you put a TC on a lens, AF slows down.

The solution to the AF speed issue is to first focus close to your subject, then it will snap in quickly. If you must alternate focusing on close and distant subjects, AF speeds will be slow.

 

[JoeKerslake]

I still have the 1.4X TC III, and it is quite useful with both the f/2.8 IS II and the f/4 IS zooms. Focusing speed is modestly slower, but the extra reach, if needed, is worth the compromise. I sold my 2X TC III since the focus speed was significantly slower, and more to the point, for BIF, it would get lost in the sky and never recover focus. I now have the 300mm f/4 IS and the 400mm f/5.6 and never used the 2X any more. I did do some controlled sharpness tests comparing the f/2.8 IS II zoom with the 2X against the 400mm f/5.6 at 30 feet, mainly center image IQ. There was more variation from shot to shot auto focus (5 shots each) than there was difference in the IQ between the pair. If the zoom focal length range with the TC attached makes sense for a given shoot, consider it an real advantage to have that option in you camera bag. It weighs next to nothing, and you will be pleased with the IQ of the combination. If I am able to carry a crop and a FF body with me, I would choose that first, but of course you can also use the TC with the zoom on a crop. I get best results with BIF with my 6D and the 400mm, but for other wildlife that are not moving
so fast, and framed against the sky, both the 2X and the 1.4X TC IIIs were useful.

I'll be shooting on a crop so I guess it's pretty unnecessary, might rent it anyway for a couple of days and see how it works out.

 

[wsmith96]

I use this combo on a 60d and find the iq just fine. Auto focus speed isn't much slower for me either.