Ef and Ef-s what is the difference

EF can be used on a full frame (5Dmkxx/1Dmkxx) or APS-C sensor (everything else). Thge EF-S can only be used on APS-C sensor cameras. The reason is that the EF-S have to "illuminate" a smaller area as the sensor is smaller so can be made more cheaply.

It is a way of reducing the price of the lenses for most users.
 
With your camera, a 500D, you can use both with no issues. If you ever upgrade to a full frame camera like a 5D mkII you will only be able to use EF lenses.
 
I believe if you try to put an EF-S lens on a non EF-S camera you'll bash your mirror with the lens

so don't do it
 
So are ef-s lenses generally of a poorer quality than ef.

I'm looking at getting an ef-s 17-85mm is usm to replace the standard ef-s 18-55 is lens
 
No, there are some very good EF-S lenses.

Just think of it as EF-S being only for Canon APS-C cameras and EF being for any Canon SLR/DSLR be they APS-C, APS-H or full frame.

EF-S lenses will not physically fit onto a Canon full frame camera but EF lenses will fit any Canon SLR/DSLR.
 
Jared said:
So are ef-s lenses generally of a poorer quality than ef.I'm looking at getting an ef-s 17-85mm is usm to replace the standard ef-s 18-55 is lens
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No, not poorer quality, just designed for crop sensors

The EF-S 17-55IS lens is an absolute cracker, it's built with virtually L series glass in it, but not the full build quality of an L series lens. This lens out performs many EF lenses.

I seem to remember, the main reason this lens doesn't have an L on it and a red band is Canon won't produce an L series lens thats an EF-S fitment.
 
The 17-55 IS is a stunning lens. It produced images as sharp as my EF 100mm f/2.8L macro.
They are different things for different uses, you cant really compare them quality wise.
If you are considering upgrading to full frame in the future, it might be wise to focus on EF lenses, but if you are not, then there is nothing wrong at all with EF-S lenses.
 
Ok what about the 17-85mm ef-s lens the 17-55mm is a little to pricey for me.
 
Jared said:
Ok what about the 17-85mm ef-s lens the 17-55mm is a little to pricey for me.
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TBH, that particular lens is not one of Canon's finest. It has good range, light, well made and nice to use, but optically it's no better than the regular kit jobbie. On the other hand, running Raw files through Canon's free DPP software (came with the camera) makes a huge difference to vignetting, CA and distortion - all of which the 17-85 has a fair bit of.

If you can't stretch to the wonderful 17-55 2.8, how about the new 15-85? Range is fantastic and it's very sharp :thumbs:
 
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that's still to expensive sorry. This has kind of diverged from the original thread now though, so i'll leave it there and post a new question on what lens.

Thanks all
 
how about a tamron 17-50mm non VC?

Nearly as good as the 17-55mm canon, but cheaper.
 
To answer the OP's original question, and add a whole bunch more useless information at the same time...

The Canon EF mount was introduced in 1987. EF stands for "Eelectronic Focus". The EF mount was, as far as I am aware, the first all-electronic interchangeable lens mount for SLRs - Others have mechanical linkages. The flange focal distance of the EF mount is 44mm (ie the distance from the lens mount plane to the film/sensor plane).

EF-S stands for "Eelectronic Focus - Short back focus". Catchy.

EF-S lenses are designed around two aspects of APS-C (crop sensor) bodies. The first, that everyone knows and loves, is that the lens can offer a reduced image circle since it doesn't have to cover the full 35mm frame (which requires an image circle approx 43mm diameter. Note this is why MTF graphs go to 21.5mm). The image circle for an EF-S lens is around 27mm diameter.

The second, and the root of the name, is that the smaller frame size means that the main mirror in a crop body can be made smaller. Since it is smaller, it doesn't come so close to the lens when swinging upwards, so there is some space inside the body that the rear of the lens can protrude into. This allows rear elements to be placed closer to the sensor plane (although the flange distance is still the same). This helps in designing wide-angle lenses, as most EF-S lenses are (the 60mm macro being the one exception).
 
I know that that's the theory but other companies seem to be able to make APS-C only lenses that don't need to intrude as far into the camera body as EF-S without any apparent image quality reduction so I've always wondered if Canons approach was actually worth the effort and inconvenience of not being able to use EF-S lenses on non EF-S bodies.
 
It's not so much as "seem to be able to" but rather that the likes of Sigma etc are designing lenses to work on all APS-C bodies from different manufacturers. All of these bodies have different flange-mirror clearances so the lenses must be designed to a conservative lowest common demoninator.

In other words, because they're not designing specifically for EF-S, they are unable to take full advantage of it.
 
That's my point.

Pick any EF-S lens and there'll be a (possibly) superior third party lens so I do wonder why the additional intrusion into the body was necessary. Theoretically I don't doubt that there's an advantage but in practice there just doesn't seem to be.
 
woof woof said:
That's my point.

Pick any EF-S lens and there'll be a (possibly) superior third party lens so I do wonder why the additional intrusion into the body was necessary. Theoretically I don't doubt that there's an advantage but in practice there just doesn't seem to be.
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There are no superior lenses for crop format than EF-S. Nothing beats the 10-22 for range and performance, and the 17-55 2.8 IS is peerless. The 17-55 2.8 Nikon is not quite as good optically, costs more money, and doesn't have IS. The fact that you might also be able to use it (badly) on a D3 seems a bit pointless.

The extra few mms of back focus that Canon have exploited with EF-S is worth it IMHO. And why anyone with a full frame camera should want to put crop format lenses on it, I don't know. If Canon has a problem, it's with the 1.3x crop 1D series which is a bit strangled at the wide end - it loses out on the full benefit of EF lenses and cannot take EF-S (not without a bodge, anyway). I guess Canon would say the 1D cameras are for long lens action and high end users are likely to have another body to cover other things, but it certainly stops me lusting after a 1D4.

BTW, the 55-250 EF-S also breaks the below 44mm rule, but it's not a hard line. Just that the benefits of EF-S quickly run out after about 50-60mm. Neither Nikon nor Canon makes a crop format lens that starts at a longer focal length than that.
 
If only everything in life was as certain as you seem to be.

I've actually owned a 10-22mm and although it's considered to be one of the better EF-S lenses it suffers from a level of distortion and vignetting that it's competitors seem to be able to match or better. I'd argue that the 17-55mm is a bit of a special case as I'm not aware of any direct competitor for a Canon body as the third party lenses such as the Tamron 17-50mm f2.8 seem to be built much more to a budget and are I believe considerably lighter and less bulky.

As for APS-C lenses on FF bodies, Nikon seem to see sense and surely that's up to the user to decide.
 
woof woof said:
If only everything in life was as certain as you seem to be.

I've actually owned a 10-22mm and although it's considered to be one of the better EF-S lenses it suffers from a level of distortion and vignetting that it's competitors seem to be able to match or better. I'd argue that the 17-55mm is a bit of a special case as I'm not aware of any direct competitor for a Canon body as the third party lenses such as the Tamron 17-50mm f2.8 seem to be built much more to a budget and are I believe considerably lighter and less bulky.

As for APS-C lenses on FF bodies, Nikon seem to see sense and surely that's up to the user to decide.
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Loved my 10-22 :)
 
There are very good lenses in both the EF and EF-S ranges.
If you are on a budget and want to replace the kit lens then maybe get the Tamron 17-55mm non VC.
 
HoppyUK said:
Neither Nikon nor Canon makes a crop format lens that starts at a longer focal length than that.
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Nikon make an 85mm DX format prime. Not one of their finest decisions but even so, it does start above 55mm
 
Yes, the 55-250 doesn't really use the short back focus issue - it simply takes advantage of the reduced image circle, but canon still fit it with the EF-S back end rubber/plasticy bit so that it can't be fitted to full frame cameras. It isn't that all EF-S lenses use both aspects, it's just that they can.
 
boyfalldown said:
Nikon make an 85mm DX format prime. Not one of their finest decisions but even so, it does start above 55mm
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As far as I know, Nikon makes three 85 lenses, all FX format.
 
As an EF-S lens is designed for a cropped sensor, does that mean you get the true 17-85mm (as an example) range? Or is it still 17-85mm x1.6?

I hope the above makes sense lol
 
A 50mm lens is a 50mm lens. On "full frame" it's normal, on APS-C it's a mild telephoto and on medium format it's wide angle. The length printed on the lens is its optical focal length. Field of view is down to format.

In other words, an EF-S 17-85 and an EF 17-40 both have exactly the same FOV at 17mm on an APS-C body.
 
wookey said:
As an EF-S lens is designed for a cropped sensor, does that mean you get the true 17-85mm (as an example) range? Or is it still 17-85mm x1.6?

I hope the above makes sense lol
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It's still 17-85mm x1.6


As for EF-S quality nothing is as good as the 17-55 f2.8 IS. It matches or exceeds the optical performance of any L-Series zooms with similar focal length range, and the EF-S 15-85mm f/3.5-5.6 IS USM is a very very good lens too apparently.
 
whiteflyer said:
It's still 17-85mm x1.6

As for EF-S quality nothing is as good as the 17-55 f2.8 IS. It matches or exceeds the optical performance of any L-Series zooms with similar focal length range, and the EF-S 15-85mm f/3.5-5.6 IS USM is a very very good lens too apparently.
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No. This is just confusing - see post #29.

Maybe it helps to remember that what we're talking about here is the 'crop factor' - it's the format that's been cropped, the sensor is smaller. The lens focal length has not be altered in any way.

The crop factor is just an easy way of working out what the field of view is with a given lens if you switch between formats, and as such it is the equivalent focal length. It's just a guide, rule of thumb, whatever.
 
I thought as much, but just thought I'd ask the question (probably worded badly...lol)

So an EF-S 17-85mm still has a focal length range equivalent to 27-136mm in 35mm format.

So is the EF-S range purely about manufacturing/cost ?
 
wookey said:
I thought as much, but just thought I'd ask the question (probably worded badly...lol)

So an EF-S 17-85mm still has a focal length range equivalent to 27-136mm in 35mm format.

So is the EF-S range purely about manufacturing/cost ?
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This was the original reason I asked the question and it would seem that you have summed it up perfectly there.
 
wookey said:
I thought as much, but just thought I'd ask the question (probably worded badly...lol)

So an EF-S 17-85mm still has a focal length range equivalent to 27-136mm in 35mm format.

So is the EF-S range purely about manufacturing/cost ?
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I'll just pick you up on that last point about cost, it's more than that.

Lens design is about compromise, and there are lots of aspects to that, but one of the most difficult things to do optically is project the image over a large area, ie over a full frame sensor, especially if you want to do it with a low f/number.

With the smaller image area of crop format cameras, the designer has more wriggle room, and can make a better lens. A good example of that is the Canon EF-S 17-55 2.8 IS, compared to the EF 17-40L 4. The EF-S lens has a lot more range, double the light gathering capability (f/number) and also has IS.

Or put that another way, and compare it to the EF 16-35L 2.8 - that lens only achieves f/2.8 because the focal length range has been cut even further, and the size, weight and cost all go up substantially. And still no IS. Then there's the EF-S 10-22, which is a practical impossibility to make with full frame coverage.

If you use short focal length EF lenses on a crop format camera, you are not only paying for extra sensor coverage that you can never actually use, you are also losing out on some major benefits inherant to the format.
 
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HoppyUK said:
Then there's the EF-S 10-22, which is a practical impossibility to make with full frame coverage.

If you use short focal length EF lenses on a crop format camera, you are not only paying for extra sensor coverage that you can never actually use, you are also losing out on some major benefits inherent to the format.
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Why is that?

Nikon and Sigma both make ultra wide FX format lenses that are very well thought of and although they don't either go to 10mm they do go close. I think there is a commercial consideration in all this - would the market be there for a 10mm fx lens? 12mm is already insanely wide on a full frame body.

I can see how the designers get major benefits from a crop format lens, but why does the end user lose out?
 
boyfalldown said:
Why is that?

Nikon and Sigma both make ultra wide FX format lenses that are very well thought of and although they don't either go to 10mm they do go close. I think there is a commercial consideration in all this - would the market be there for a 10mm fx lens? 12mm is already insanely wide on a full frame body.

I can see how the designers get major benefits from a crop format lens, but why does the end user lose out?
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I'm not sure I'm following you here. Sure, there's a cost consideration (which is why I said a 'practical' impossibility) but if you look at what Sigma and Nikon produce, well neither runs down to 10mm as you say, and that is a very long way from Sigma's 12mm and Nikon's 14mm. And both have huge bulbous front elements so you can't fit a normal filter. Then again, the Sigma's performance is hardly state of the art, despite a very modest maximum aperture and £600 cost, and the Nikon is more than double that.

On the other hand, for crop format cameras, several manufacturers produce very good quality lenses around 10-20ish, and affordable prices. If it wasn't for the reduced image circle of these lenses, crop camera users wouldn't have anything at all really wide and affordable, with decent performance.

What do you mean 'why does the end user lose out' with EF-S? The user benefits - a lot.
 
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