300 f4 w/1.4x or 400 f5.6

[Birdshooter]

I would recommend the version II rather than the version III extender.

Why?

There is, in combination with the 300 f/4, no benefit in sharpness in the new 1.4x III version to the old 1.4 II version. AF is not any faster as well. It's just twice the amount of money.

 

[danski0224]

There is, in combination with the 300 f/4, no benefit in sharpness in the new 1.4x III version to the old 1.4 II version. AF is not any faster as well. It's just twice the amount of money.

Ah. Thanks

 

[risc32]

have i shot with a 400mm lens? well, no not 400mm. I stated in my post that I use my 300mm2.8 with a 1.4 tele. That would be about 420mm. Now with that setup on a 5dmk3 wide open I'd still like less DOF. And that's with the extender decreasing the DOF even if my exposure is at f4(wide open). Really, so much silly stuff has been written since my post that i really don't have the patience to respond. So if you can't beat them join them. So I say sure, with your current gear in mind, if you would sometimes like a bit more reach buy a 7d, or a 200-400mmf4 or perhaps that 400mm2.8 monster.
Now I should go and respond to the guy wanting to know how to get photos out of his camera. I think i'll suggest he get's some custom workstation made up for that, or whatever top end stuff Apple's got.

 

[Razor2012]

I would recommend the version II rather than the version III extender.

Why?

There is, in combination with the 300 f/4, no benefit in sharpness in the new 1.4x III version to the old 1.4 II version. AF is not any faster as well. It's just twice the amount of money.

A quote from The-Digital-Picture.com:

"The image quality differences most easily noticed between the 1.4x II and the 1.4x III are:

The 1.4x III has less barrel distortion than the 1.4x II. This makes the center-of-the-frame details slightly smaller in a comparison. This difference will be most noticeable in the top crop shown in the ISO 12233 chart tool.

Anomalous dispersion glass elements are used in the Series III extenders to reduce chromatic aberration and increase resolution and contrast. The CA difference between the II and III is quite noticeable - pay close attention to this difference in the bottom ISO 12233 crops.

Less noticeable are the resolution and contrast differences, but some comparison examples do show improvements.

Contributing to the improved image quality is Canon’s Super Spectra coating which reduces ghosting and flare. Front and rear elements have Canon's fluorine anti-smear coating - making them very easy to clean.

Not available as I create the Canon EF 1.4x III Extender review are the announced:
Canon EF 300mm f/2.8 L IS II USM Lens,
Canon EF 400mm f/2.8 L IS II USM Lens,
Canon EF 500mm f/4 L IS II USM Lens and
Canon EF 600mm f/4 L IS II USM Lens.
Improvements in the Series III extenders promise to perform especially well on these specific lenses.

A microcomputer integrated into the Series III Extenders promises faster autofocusing and increased AF precision when used with the Canon IS Supertelephoto Series II lenses mentioned above and (I expect) all future compatible lenses. Better optical quality is also expected.

Note that "AF precision remains the same as the Series II Extenders when the Series III Extenders are used with earlier extender-compatible EF lenses." [Canon]

Note that Canon does not recommend stacking extenders. While they do not fit together due to the lack of space at the rear elements, an extension tube installed between them can be used to make the fit possible. But, Canon does not recommend using ETs at all due to reduced autofocus accuracy. Image quality from stacked extenders will not be great."

 

[wickidwombat]

you can stack a 2x canon extender with a kenko 1.4 extender because the kenko extenders fit any lens

 

[Michael_pfh]

I would recommend the version II rather than the version III extender.

Why?

There is, in combination with the 300 f/4, no benefit in sharpness in the new 1.4x III version to the old 1.4 II version. AF is not any faster as well. It's just twice the amount of money.

A quote from The-Digital-Picture.com:

"The image quality differences most easily noticed between the 1.4x II and the 1.4x III are:

The 1.4x III has less barrel distortion than the 1.4x II. This makes the center-of-the-frame details slightly smaller in a comparison. This difference will be most noticeable in the top crop shown in the ISO 12233 chart tool.

Anomalous dispersion glass elements are used in the Series III extenders to reduce chromatic aberration and increase resolution and contrast. The CA difference between the II and III is quite noticeable - pay close attention to this difference in the bottom ISO 12233 crops.

Less noticeable are the resolution and contrast differences, but some comparison examples do show improvements.

Contributing to the improved image quality is Canon’s Super Spectra coating which reduces ghosting and flare. Front and rear elements have Canon's fluorine anti-smear coating - making them very easy to clean.

Not available as I create the Canon EF 1.4x III Extender review are the announced:
Canon EF 300mm f/2.8 L IS II USM Lens,
Canon EF 400mm f/2.8 L IS II USM Lens,
Canon EF 500mm f/4 L IS II USM Lens and
Canon EF 600mm f/4 L IS II USM Lens.
Improvements in the Series III extenders promise to perform especially well on these specific lenses.

A microcomputer integrated into the Series III Extenders promises faster autofocusing and increased AF precision when used with the Canon IS Supertelephoto Series II lenses mentioned above and (I expect) all future compatible lenses. Better optical quality is also expected.

Note that "AF precision remains the same as the Series II Extenders when the Series III Extenders are used with earlier extender-compatible EF lenses." [Canon]

Note that Canon does not recommend stacking extenders. While they do not fit together due to the lack of space at the rear elements, an extension tube installed between them can be used to make the fit possible. But, Canon does not recommend using ETs at all due to reduced autofocus accuracy. Image quality from stacked extenders will not be great."

The Canon 1.4x II and the Canon 2.0x II fit together without any problems. Of course the IQ will go down at lot due to the stacking...