Canon EF versus EFS Lenses

Discussion in 'Beyond the Basics' started by Paul_the_6th, Jun 14, 2006.

  1. Paul_the_6th

    Paul_the_6th TPF Noob!

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    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.
     
  2. magicmonkey

    magicmonkey TPF Noob!

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    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)
     
  3. Paul_the_6th

    Paul_the_6th TPF Noob!

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    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!
     
  4. magicmonkey

    magicmonkey TPF Noob!

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    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.
     
  5. JamesD

    JamesD Between darkrooms

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    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!
     
  6. magicmonkey

    magicmonkey TPF Noob!

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    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!
     
  7. Paul_the_6th

    Paul_the_6th TPF Noob!

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    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 :)
     
  8. magicmonkey

    magicmonkey TPF Noob!

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    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...
     
  9. JamesD

    JamesD Between darkrooms

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    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.
     
  10. Paul_the_6th

    Paul_the_6th TPF Noob!

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    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!
     
  11. magicmonkey

    magicmonkey TPF Noob!

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    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...
     
  12. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    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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