EF vs. EF-S What's the difference?

[keith204]

Is 18mm on an EF lens the same as an EF-S? For instance, my 18-55... is it really 18-55 Stock EF-S on my Rebel XT, or do I need to multiply that x1.6?

Digital Rebel XT
Canon EF-S 18-55
Canon EF 28-105 f/3.5-4.5 USM II
Canon 50mm f/1.8
Sigma 70-200 f/2.8 DG EX HSM Macro
Canon Speedlite 430EX

 

[tempra]

They are the same focal lengths, so you need to multiply it to get an quivalent 35mm view

 

[keith204]

So, you're saying that 28mm on a EF-S lens is the SAME as 28mm on a EF lens? (on a digital camera [rebel xt])

 

[WDodd]

EF and EF-S lenses are the same at any focal length. EF-S lenses will only work on cameras that are not full frame (300D, 350D, 400D, 20D, 30D). In other words you can't use an EF-S lens on a 35mm camera. The "S" stands for short back focus by the way.

If you hold a EF and an EF-S lens up to each other you can tell that the EF-S lens on the side that connects to the camera will sit farther into the camera. Canon designed these lenses that way specifically for cameras with smaller sensors.

If you want to find the 35mm equivalent of any focal length through the XT you'll have to multiple it by 1.6.

Hope that clears up the confusion on the difference between EF and EF-S lenses.

 

[Don Simon]

Yes, an EF-S lens with a focal length of 28mm gives the same field of view as a full-frame EF-S lens, if you are using them both on the same size sensor. Any 28mm lens on a digital Rebel (with the 1.6x 'crop') will give that field of view. The difference is that an EF-S lens is designed to only cover that size sensor, so it won't work properly on a full-frame sensor, but that won't be a problem for use on your XT.

Edit: I got beat to this one

 

[Big Mike]

That's correct...the crop factor applies to the lens on a specific camera not the lens itself...it's really only a comparison number...used to compare the field of view on a 'crop body' to what the industry is used to...that being 35mm film cameras.