danersmiff

Canon's EF Extender 1.4Xiii and 2Xiii do not list any EF-S lenses on their compatibility charts.
Why do they not work for EF-S lenses, or is it the Crop sensors, or both?

Also, I have a couple of the EF lenses on the list, so will the extenders work with those on my 7Dii?

thanks- d---

MT Shooter Loc: Montana

EF-S lenses will NOT mount on Canons extenders, for the same reason they will not mount on Canon full frame cameras. These extenders are also not compatible with many full frame Canon lenses, primarily those zooms offering variable aperture ranges.
After market brand crop sensor lenses will often mount but may present other issues.

CHG_CANON Loc: the Windy City

The extenders literally extend into the lens they're connected to. Only certain models of the L-lens line are designed in a way the extender can be physically connected to the compatible lenses. That is, there's space between the rear glass element of the compatible lens and the bottom of the lens where it connects to the camera. Or in the case of Canon extender, when the Canon L lens is connected to the extender, the glass in the extender 'extends' into that open space at the end of the lens.

Extenders are not limited to full-frame EOS bodies. However, the 1- or 2-stop loss of light hitting the sensor when the extender is used may disable the ability to auto-focus on most EOS models, particularly the lower-end cropped-sensor bodies. The EOS 7DII and 80D models can autofocus a lens+extender combination with a maximum aperture of f/8. Other cropped bodies are limited to f/5.6. A 1.4 extender with an f/2.8 lens for an effective f/4 would be compatible with all EOS DSLR bodies, although your selection of compatible f/2.8 lenses is limited to the 70-200L f/2.8L zooms and the 200, 300, and 400 f/2.8L primes. These f/2.8 lens are also compatible with the 2x extenders and all EOS bodies to retain autofocus at an effective f/5.6 maximum aperture.

amfoto1 Loc: San Jose, Calif. USA

The EF-S mount is designed to prevent the lenses from being installed on EF mount cameras, which are what the Extenders use. But even if they could be mounted...

All the Canon Extenders have protruding front element that fits inside the rear barrel of the lens they're used upon. No EF-S lens has large enough diameter barrel to accommodate the Extender (neither do a lot of EF lenses, for that matter).

In addition, "EF-S" stands for "EF-short", because some of the lenses use a design that moves the rear element back, sometimes even within the camera body, because they are intended for use only on cameras that have smaller mirrors that won't interfere with them. Those lenses' rear element would come in contact with the front element of the Extender.

Not to mention, there are precious few EF-S lenses that it makes any sense at all to use a teleconverter on... at most, the EF-S 55-250 and maybe EF-S 18-135mm or 15-85mm.

If you really want to use an extender on an EF-S lens, Kenko makes an "HD" line with 1.4X and 2X that will fit both EF-S and EF. (Their Pro 300 and MC4 series TCs only work with EF lenses.)

I wouldn't expect much in the way of image quality, though.

gordone Loc: Red Deer AB Canada

The extenders protrude into the back of the lens and on many of the lenses there is not enough space to allow that. You can check on the Canon website to see what lenses the extenders are compatible with.
http://learn.usa.canon.com/resources/articles/2014/ef_extenders_pt2.shtml

danersmiff

MT shooter, ChgCanon, amfoto1, and Gordone,

Thank you all for taking the time to answer.
Now I know!

NormanTheGr8 Loc: Racine, Wisconsin

I use a1.4x III with the 100_400LII on my 7D2 as stated above I do lose light,the autofocus does work but I am limited to 5 focus points although for birds I'm usually useing just the center point anyway

imagemeister Loc: mid east Florida

Yes, they will "work" ....but they will work better on full frame bodies where the reach is more needed and the higher ISO dictated by the extender use is more easily accommodated.

For high MP crop frame bodies, it is more advantageous to maximize your lens' IQ and CROP using well applied pixel enlargement software if needed.

..

MountainDave

I have had excellent results using the 1.4X with a 100-400L II on a 77D. However, when fully extended (894mm equivalent) getting sharp handheld shots can be difficult depending on steady you are. I try to prop on a knee, fence or hold like a rifle. I use it more often with my 5D IV but having a nearly 900mm capability is a lot of fun.