# what does EF and EF-S mean?



## cgennoe (Jul 10, 2008)

Hey!

What does EF and EF-S stand for on Canon's lineup of lenses and what is the meaning of each classification?

Thanks!


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## Mystwalker (Jul 10, 2008)

I'm sure someone will give you the exact wording ...

Here is my understanding. 
EF works on all Canon
EF-S will only work on Canon's x1.6 crop cameras such as XT, XTi, 10/20/30/40Ds.


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## KabeXTi (Jul 10, 2008)

I'm not 100% sure on this, but I'm pretty sure that EF-S is specifically for Digital Camera's only and EF would be interchangeable between film and digital.


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## Big Mike (Jul 10, 2008)

That's correct.

EF is Canon's line of auto focus lenses for their auto focus (EOS) cameras.

EF-*S* is Canon's line of lenses that are designed specifically for the 'crop factor' camera bodies as mentioned above.  These lenses have a smaller image circle and protrude slighter farther toward the camera.  That means that they are not compatible with Canon's film SLR EOS cameras or the 'full frame' digital bodies like the 5D or 1DS.


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## Village Idiot (Jul 10, 2008)

Mystwalker said:


> I'm sure someone will give you the exact wording ...
> 
> Here is my understanding.
> EF works on all Canon
> EF-S will only work on Canon's x1.6 crop cameras such as XT, XTi, 10/20/30/40Ds.


 

The 10D is an EF mount, despite the 1.6x crop sensor.


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## lostprophet (Jul 10, 2008)

From memory EF stands for *E*lectro*F*ocus

as for the -s, who knows, every time I've asked someone at Canon they never know the answer


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## reg (Jul 10, 2008)

lostprophet said:


> as for the -s, who knows, every time I've asked someone at Canon they never know the answer



Well you must be asking the wrong people because it's on wikipedia (and yes it's confirmed at other sources too, I'm just saying that searching wikipedia for "EF-S" brings it right up, near the top of the page, so it's *fairly* well known info) that it means "short back focus"


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