# Canon EF versus EFS Lenses



## Paul_the_6th (Jun 14, 2006)

Just mentioned to one of the technicians from a company I work with that I was getting my 350d on friday. He asked what lenses I was going to buy and we eventually got on to EF and EFS lenses. He briefly explained about the 0.6 magnification rule and left me feeling than a dog that had been shown a card trick.

As far as I understood it, the EF lenses are the older/film lenses, and the EFS lenses are designed to run with digital SLR's because the sensor is 0.6 of the size of a 35mm frame?

Is this correct and what lenses should I look for. I wouldn't mind a decent mid ranger which gives good portrait/snapshotting but has a decent zoom. This way I don't have to carry a great deal of lenses when I'm on the move.

Failing that I wouldn't mind a decent macro lense and a decent zoom lens... what ya reckon?

He also said alot of people are selling off their old gear on ebay without realising the lens is still worth a bomb and that I should look into it.


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## magicmonkey (Jun 14, 2006)

if you times the focal length of an EF lens by 1.6 then you end up with the 'correct' focal length on a cropped body (DSLR with a smaller sensor).
For example, a shot focused at 300mm will have an effective focal length of (300 * 1.6 =) 480mm. The reason for this is a bit harder to explain without pictures so bear with me!

The EF lenses focus light onto a 35mm sensor/film and from there you get a picture of a certain size (we'll say 4" by 6" for example), the EF lens focussing light onto a 1.6 sensor also makes picture at a 4" by 6" but as the sensor is smaller the image is cropped (ei. there is light going in but not picked up by the additional area available on a 35mm sensor) This smaller image is then streched to make your 4" by 6" print. This means you only use the middle of the lens as the data from the outside doesn't hit the sensor, it also means that although you are getting more zoom it's actually ditigal zoom rather than optical zoom.

I've probably not explained this very well but here's a link that should help you out a bit more. just read 350D where they say 20D as they have the same size sensor.

With the EFS lenses you get exactly what the lens says on a cropped body.

I have no idea what would happen if you put a EFS lens on a full frame camera but it's something I'd be interested to know as I'm thinking about buying an EFS lens but don't want it to be useless if I upgrade, anyone?

As for what lenses to buy, I have these and although they're not top of the line they will do quite well until I can afford better and cover a good focal range:

Sigma 18-50 DG (DG is the Sigma version of EFS rather than EF)
Canon 28-105 USM (EF Lens)
Canon 70-300 IS USM (EF Lens)


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## Paul_the_6th (Jun 14, 2006)

so although an EF lens *will* work, if I want to avoid heavy maths during purchasing a lens, an EFS will do exactly what it says on the tin and save me some hassle?

And, no you did explain it very well - basically if I don't do my maths and shoot at what i _think _is the correct focal length, I'm gonna get a cropped/naff image. as for digital zoom, it should be cast into the murky depths of narg - some unknown place where everyone wears grey and there are no vowels which makes it very difficult to talk.

Once I've had my camera for a week or two I'll probably bob into a photoshop and try out a couple of lenses to get an idea of what im after...

Thanks for your help!


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## magicmonkey (Jun 14, 2006)

well, that's just the technical side of it, in real terms you can get just as good a shot with EF lenses (so I'm told by a friend who uses both types) and the EF lenses will fit a full frame body so are good to get if you're wanting to upgrade later, that's why I'm a bit funny about buying EFS lenses, especially when we're talking about a lot of money for one of these things.


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## JamesD (Jun 14, 2006)

You can put an EF lens on any EOS camera with absolutely no problems whatsoever.  If you put an EFS lens on a film body, or a full-frame digital, then you will have problems.  From what I understand, the EFS lenses project a smaller circle of light so the image will not cover the entire frame.  Also, the distortion is kept to a minimum in the area covered by the sensor, which is smaller than a 35mm frame, with a full-frame body, you may get more distortion as you get farther from the center of the frame.

Worst case scenario of EFS lens on full-frame body:  Edges of frame are dark, and show excessive amounts of various types of distortion.

I'm not sure whether the EFS lenses are marked in equivalent focal lengths relative to film camera lenses.  I don't see any reason why they should be; I mean, after all, medium format lenses, where a normal lens is 80mm instead of 50mm, don't give you a corrected focal length.  So I don't know.  However, it really shouldn't matter, especially if you have a zoom that covers from moderately wide to moderately narrow.

As usual, I'm interjecting a bit of the logic of my thinking here, which I should've learned by now isn't usually wise.  If I'm way off base and have no idea what I'm talking about, someone set me straight!


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## magicmonkey (Jun 14, 2006)

Paul_the_6th said:
			
		

> basically if I don't do my maths and shoot at what i _think _is the correct focal length, I'm gonna get a cropped/naff image.



You still get what you see through the viewfinder so you don't actually have to do any working out while taking a shot as you're only shown the cropped image, no real disadvantage here as far as I'm aware...

I should add that I'm just a beginner and if someone more experienced contradicts me then go with them instead!


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## Paul_the_6th (Jun 14, 2006)

magicmonkey said:
			
		

> You still get what you see through the viewfinder so you don't actually have to do any working out


 

ah, cashback so you don't have to work anything out before hand, just shoot as if there's no working out to do? But does the image quality still suffer the "Digital Zoom effect" like you mentioned before?

If there's no obvious loss of quality and you can compensate for the difference by eye then I can't see any problems what so ever


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## magicmonkey (Jun 14, 2006)

There's no loss of quality and no working out to do, it's more a question of which lenses you want. The only working out you should do is when you buy a lens, just take the focal length and times it by 1.6 for EF lenses...


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## JamesD (Jun 14, 2006)

When using a digital camera with either EF or EFS lenses, the _image quality_ should be the same (barring imperfections in the glass, which is something entirely different and unrelated and doesn't effectively matter here).  The only effect you get is the 1.6X magnification versus a full frame camera.  The sensor still has just as many pixels in it.

So, no, the image quality won't suffer.  The filesize and number of pixels will be the same.  You won't _see_ any difference, other than the fact that, instead of getting a head and shoulders portrait of someone, you might just get their head.  The answer for that:  step back until you have head and shoulders.  Either way, the final image will be of the same quality.


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## Paul_the_6th (Jun 14, 2006)

wickedy split dip tic toc - bought the 350d from ebuyer for £471 which is the lowest price i could find on the net. Jessops seem good for advice but net prices can be alot cheaper than their best instore offers.

Which are the definitive websites for photography kit?

Cheers for all the replies!


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## magicmonkey (Jun 14, 2006)

one of the cheapest I've found so far is www.warehouseexpress.com I've only used them once though so can't really comment on their service. Though I hate to say it, ebay can save you a fortune if you don't mind waiting for things to arrive from hong kong. You can always ask here if people have used an ebay seller to make sure they're ok...


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## Big Mike (Jun 14, 2006)

Do you own or have you used a 35mm film SLR?  If not, then don't worry about the 1.6 crop factor...it will mean nothing to you.  The crop factor gives you the equivalent FOV (field of view) that you would have...on a 35mm camera.  So a 50mm lens on your 350D will have the same FOV as an 80mm lens on a 35mm camera.  *But if you don't have a preconceived notion of what the FOV of a 50mm lens is supposed to be....then don't worry about the difference*.  Just put it on your camera and shoot.

EF-S lenses will actually not work on EOS film cameras or full frame digital.  The rear element of the lens protrudes into the camera and would interfere with the movement of the mirror.  The few digital bodies that can use EF-S lenses have smaller mirrors.


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## Paul_the_6th (Jun 14, 2006)

Big Mike said:
			
		

> Do you own or have you used a 35mm film SLR? If not, then don't worry about the 1.6 crop factor...it will mean nothing to you. The crop factor gives you the equivalent FOV (field of view) that you would have...on a 35mm camera. So a 50mm lens on your 350D will have the same FOV as an 80mm lens on a 35mm camera. *But if you don't have a preconceived notion of what the FOV of a 50mm lens is supposed to be....then don't worry about the difference*. Just put it on your camera and shoot.
> 
> EF-S lenses will actually not work on EOS film cameras or full frame digital. The rear element of the lens protrudes into the camera and would interfere with the movement of the mirror. The few digital bodies that can use EF-S lenses have smaller mirrors.


 
I used a film slr for about a week 2 years ago on a college project. Had to develop and everything from start to finish - that was what got me into photography in the first place but having only used a prosumer compact for the past year or so, I just wanted to make sure the images would come out as good as any other, i.e. no unforseen cropping etc but as everyone has said, any difference is visible to the naked eye and can be sorted by moving closer or further away etc 

Superp. Will check out warehouseexpress but ebay seems to be proving one of the best options


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## sothoth (Jul 6, 2006)

I was worried about EFS being discontinued after reading some of the posts in this thread (and on other photo forums) but asked a few people who know a bit about CMOS sensor fabrication, and now I'm convinced they won't discontinue them. 

First, the most expensive part of making a sensor is the silicon "real estate" it's built on, so bigger sensors (assuming the same number of pixels) are more expensive to fabricate than smaller sensors. 

Next, pixel density is increasing over time (remember Moore's law?), with little or no cost increase for higher density. Fabrication techniques are improving every day, so pretty soon you won't need to make a BIGGER sensor to squeeze more pixels onto it. Thus you'll get equally sharp images with good dynamic range and at a lower cost for the small sensor.

Thus, I think Canon will stick with the EFS lenses since the small size has cost advantages.  Besides, the Digital Rebel is probably their best selling digital SLR, so why mess with the lens selection for their flagship semi-pro camera?

I suspect the quality of the EFS lenses themselves will go up as they put more into making them out of the higher grade glass, etc. I think they'll maintain both types of lenses and have a pretty comparable selection and quality range for each line. They've pretty much built themselves into that corner but I'm not complaining.  I plan on seeing both types of lenses around and Canon will continue to make small sensors on their entry level DSLRs and slightly bigger sensors for their pro level DSLRs.  

Comments are appreciated.


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## DonSchap (Jul 6, 2006)

EF-S lenses will NOT mount on Full Sensor (FS) digital camera or 35mm-film bodies.

If you look carefully at an *EF-S* lens, it has a small white _square_ as an index mounting mark, rather than the standard *EF* red dot. The mounting ring is also constructed to forbid mounting on Full Sensor (FS) and 35mm cameras. There is also no white _square_ on FS or 35mm bodies. You will only see a corresponding white _square_ and the round red dot on the APS-C digital cameras (350D/20D/30D) mounting ring, as this type of camera can mount BOTH types of lenses.

If you look at the rear of an *EF-S* lens, you will also notice a 3/8" projection ring. If you actually could mount the lens on your FS digital or 35mm, the reflex-mirror of your camera would whack against this projection, possibly damaging it.

TAmROn *Di II* lenses are not to be confused with *EF-S* lenses. They are not the same... as they are designed to index on the *EF* red dot, so you could use them on the FS digital and 35mm... but, you are warned by the manufacturer, you will encounter serious issues doing this. *Di II* lenses are designed to be used by APS-C sensor cameras.

I hope this clears the air... looks like the *EF-S* lenses are here for awhile.


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## markc (Jul 7, 2006)

To put what Mike was saying another way, there is no actual multiplications going on. You only do that if you are used to shooting with a 35mm camera and want to get an idea of what the lens is going to behave like. A 50mm is still a 50mm lens, no matter what camera it's on. On a disc, APS, instamatic, or 350D, a 50mm lens is a telephoto. On a 35mm film camera or 5D, it's a normal lens. On a medium format camera, it's a wide angle, and on a 4x5, it's an ultra-wide.

There is no difference between focal lengths when comparing EF and EFS lenes. It's just the EFS can be built smaller, so it's easier to make them wide angle.


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## 964 (Jul 7, 2006)

Basically - DON'T BUY EF-S LENSES IF YOU THINK YOU WILL UPGRADE YOUR BODY AT SOME POINT!


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