Canon EF 70-200mm f/2.8L USM IS Type I + Canon EF 2,0 x extender III

[charliebravo]

J'utilse actuellement un Sigma AF 150-500mm f/5-6.3 DG pour la photo d'oiseaux, mais celui rate 7/10 images à 500m avec un EOS 7D, en failble lumière.

Je possède un Canon EF 70-200mm f/2.8L USM IS Type I.

Question le couple Canon EF 70-200mm f/2.8L USM IS Type I  +  Canon EF 2,0 x extender III sera-t-il plus performants que le Sigma en faible lumière?

A+

[Powerdoc]

non, car l'AF est très aléatoire. L'extender type 3 n'est un avantage qu'avec les derniers grands blancs, comme le 70-200 2.8 LIS 2 ou 300 2,8 LIS 2, mais pas les versions 1.

[Rolif]

L'extender type 3 n'est un avantage qu'avec les derniers grands blancs, comme le 70-200 2.8 LIS 2 ou 300 2,8 LIS 2, mais pas les versions 1.

Le 70-200/2.8 L IS II ne fait pas partie des objectifs pour lesquels l'extender version III est optimisé.

[corwin314]

Quelle est cette fameuse liste?

[Rolif]

Quelle est cette fameuse liste?

300 f/2.8 L IS II - 400/2.8 L IS II - 500/4 L IS II - 600/4 L IS II sont les objectifs pour lesquels les TC 1.4x et 2x version III sont optimisés, ils assurent une meilleure communication avec le boîtier et un AF plus rapide. Avec les autres objectifs pas de différence avec la version II des TC.

[Powerdoc]

300 f/2.8 L IS II - 400/2.8 L IS II - 500/4 L IS II - 600/4 L IS II sont les objectifs pour lesquels les TC 1.4x et 2x version III sont optimisés, ils assurent une meilleure communication avec le boîtier et un AF plus rapide. Avec les autres objectifs pas de différence avec la version II des TC.

Oui après vérification c'est bien cela : voila un passage en anglais ou c'est signalé
On voit quand même qu'un doubleur réduit de 75 % la vitesse de l'aF, ce qui n'est pas neutre.

Below is an excerpt from Chuck Westfall's article here. This is Chuck's job title: Canon USA Advisor, Technical Information.

I will be glad to attempt to answer any questions as best as I can.

Extenders EF 1.4X III and EF 2X III

Extenders EF 1.4X III and EF 2X III have been newly developed in conjunction with the new Series II Image Stabilizer EF super-telephoto lenses. They can also be used with all previously announced extender-compatible EF lenses, but maximum performance is achieved when they are used with the new 300mm, 400mm, 500mm and 600mm lenses. The following sections provide more detailed information.

Image Quality

There are two significant improvements related to image quality when using the new Series III Extenders with the new IS II super-telephoto lenses: Anomalous dispersion glass elements are used in both new extenders to effectively reduce chromatic aberration to the greatest possible extent. This results in higher resolution and contrast, especially when the new extenders are used with IS II super-telephoto lenses.

Each Series III Extender features a newly developed microcomputer that increases AF precision when the extenders are used with an IS II super-telephoto lens. AF precision remains the same as the Series II Extenders when the Series III Extenders are used with earlier extender-compatible EF lenses.

As a result of these improvements, users of the new IS II super-telephoto lenses can expect significantly improved image quality when using Series III Extenders.

New Lens Coating

The front and rear elements of both Series III Extenders feature Canon's new Fluorine anti-smear coating. The new coating is extremely oil-and water-repellent so that the front and rear elements can be cleaned without lens cleaning solvents using a soft, dry cloth.

Durability Improvements

The Series III Extenders are significantly more durable than earlier models due to the following improvements:

Seven screws instead of four are used to attach the lens mount to the body of the extender.

The lens lock pin and lens mount stopper pin have been improved for higher endurance.
The Series III Extenders are equivalent to the Series II Extenders in terms of weather resistance, with gaskets on both the front and rear lens mounts as well as the lens mount release switch.

The durability improvements of the Series III EF Extenders were made in response to feedback from professional photographers who use EF super-telephoto lenses and extenders regularly in their daily work.

Lens Compatibility

A list of compatible lenses for the new Series III Extenders can be seen by following the link to Chuck's article at the start of this thread.

*AF may not focus accurately when a Series III EF Extender is combined with certain discontinued EF lenses marked with an asterisk in the table above. This problem can be resolved through AF Microadjustment on EOS cameras equipped with that feature. Manual focusing is recommended when using Series III EF Extenders with those particular lenses on compatible EOS bodies that do not have an AF Microadjustment function.

Camera Compatibility

The new Series III Extenders are compatible with all EOS Digital SLRs as well as the EOS-1V 35mm SLR. However, they cannot be used with other film-based EOS cameras because their signal relay system is not compatible with those models.

Other Operational Issues

The new Series III Extenders are basically the same as the Series II Extenders in terms of operation with compatible cameras. Here are a few bits of information related to usage and performance:

The Series III Extenders support autofocus when used with compatible master lenses and EOS cameras, with some restrictions as follows.

With most EOS cameras, the maximum aperture of the compatible EF lens/EF extender combination must be f/5.6 or larger to support autofocus. With EOS-1 class digital SLRs, autofocus with the center focusing point is supported for compatible EF lens/EF extender combinations with maximum apertures of f/8 or larger.

AF may not focus accurately when a Series III EF Extender is combined with certain discontinued EF lenses marked with an asterisk in the table above. This problem can be resolved through AF Microadjustment on EOS cameras equipped with that feature. Manual focusing is recommended when using Series III EF Extenders with those particular lenses on compatible EOS bodies that do not have an AF Microadjustment function.
The Extenders EF 2x III and EF 1.4X III (pictured above) make ideal companions to the new supertelephotos, adding up to twice the focal length of these, and many other Canon EF lenses without significant additional weight or cost.

Usage of Series III EF Extenders has no effect on AE (Automatic Exposure) or IS (Image Stabilizer) functionality.

Canon does not recommend stacking Series III EF Extenders because the extenders' optical performance and AF precision cannot be guaranteed in such cases.

Similarly, Canon does not recommend combining a Series III EF Extender with an extension tube because the extenders' optical performance and AF precision cannot be guaranteed in such cases.

As with previous EF Extenders, usage of Series III EF Extenders lowers AF drive speed to improve AF performance. When Extender EF 1.4X III is used, AF drive speed is reduced by 50%. When Extender EF 2X III is used, AF drive speed is reduced by 75%. This may seem like a drawback, but in reality subject tracking performance remains quite high when Series III Extenders are used with IS II lenses. This is due to improvements in AF precision made possible by the new microcomputer in the extenders.

[corwin314]

Merci