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Thread: EF lens on EF-S body

  1. #1
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    Question EF lens on EF-S body

    Hi, can anyone explain to me whether using an EF 50mm lens on a 1.6x crop body like 400d is equal to a 80mm lens on a full frame body? Am a bit confused at this and any help would be greatly appreciated. Thanks

  2. #2

    Default Re: EF lens on EF-S body

    IIRC, you still get a 1.6 crop factor, and not a 2x FOV unlike 4/3 systems.

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    Default Re: EF lens on EF-S body

    Pardon me but not really familiar with those terms
    Does that mean all i am getting is a crop from the actual picture from full frame?

  4. #4
    Senior Member Kit's Avatar
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    Default Re: EF lens on EF-S body

    Quote Originally Posted by KBblue View Post
    Does that mean all i am getting is a crop from the actual picture from full frame?
    Yes...

  5. #5

    Default Re: EF lens on EF-S body

    Quote Originally Posted by KBblue View Post
    Hi, can anyone explain to me whether using an EF 50mm lens on a 1.6x crop body like 400d is equal to a 80mm lens on a full frame body? Am a bit confused at this and any help would be greatly appreciated. Thanks
    yes. using the 50mm on ur 400D is equivalent of using a 80mm on a ff camera.

    since your 400D uses a cropped sensor with a 1.6 crop value, so what u see with a 50mm lens is actually 80mm focal length on 35mm cameras.

  6. #6

    Default Re: EF lens on EF-S body

    Think of a 'Crop Body' or 'Crop Factor' like an in-built telephoto mechanism.

    What ever lenses you use on that body, look at the 'Crop Factor', e.g., 1.3x, 1.5x, 1.6x and 2x and just use that number and multiply the lens focal length. That will give you a 'Field of View', or FOV. The FOV refers to the actual angle you see/sensor captures with a certain lens/body combination.

    CHEERS!

  7. #7
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    Default Re: EF lens on EF-S body

    So if i am using an EF-s lens, say the 18-55mm kit lens, is that the actual focal length or does the 1.6x factor still applies???

  8. #8
    Senior Member hanqiang1011's Avatar
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    Default Re: EF lens on EF-S body

    Quote Originally Posted by KBblue View Post
    Hi, can anyone explain to me whether using an EF 50mm lens on a 1.6x crop body like 400d is equal to a 80mm lens on a full frame body? Am a bit confused at this and any help would be greatly appreciated. Thanks
    Firstly you must understand the sensor size and cropped factor; both will determine the focal length of a lens. Also need to know is Focal Length Multiplier (FLM).

    The size of a full frame DSLR sensor is 24mm 36mm, which is equivilent to 35 mm film frame. Canon's 5D and 1Ds mk1,2,3 use full frame sensors. In this case, when you use a 50mm lens on a FF DSLR camera, the focal length is still 50mm.

    As the size of sensor gets smaller, say a EOS 30D camera uses APS-C-sized image sensor, which has a FLM of 1.6x, focal length gets longer. Why is it 1.6x is because the size of the sensor. APS-C-sized image sensor has a size of 22.5mm 15mm.

    22.5mm 15mm is smaller than 24mm 36mm by around 1.6 times, thus the FLM is 1.6x. Hence, when you mount a 50mm lens on a 30D, using 50mm x 1.6 = 80mm. To get back a focal length of 50mm, you will need a 35mm lens; 35mm x 1.6 = 56mm (which is around 50mm).

    In a smaller sensor, you will gain a telephoto length but lose out on wide angle length.
    Eg: Mounting a 70-200mm lens on a 30D, you get 112-320mm focal length. Mounting a 16-35mm lens on the same camera gives you 25-56mm focal length.

    In another words, FLM is to use any focal length of any lens times the size of the sensor.

    For more information, read this...
    http://en.wikipedia.org/wiki/Crop_factor

    Last edited by hanqiang1011; 12th December 2007 at 01:47 PM.

  9. #9

    Default Re: EF lens on EF-S body

    Quote Originally Posted by flipfreak View Post
    yes. using the 50mm on ur 400D is equivalent of using a 80mm on a ff camera.

    since your 400D uses a cropped sensor with a 1.6 crop value, so what u see with a 50mm lens is actually 80mm focal length on 35mm cameras.
    This is NOT correct.

    What you see is a cropped image from a 50mm lens. The crop will be equivalent to what you would see with an 80mm (approx) lens on FF. BUT, all the characteristics of the 50mm lens will still be apparent (except minor changes to DOF). Lens characteristics (except DOF, which is affected by more then just the lens)are NOT affected by a 'cropped' sensor.
    sk.images, ex - cyber_m0nkey

  10. #10

    Default Re: EF lens on EF-S body

    It can get a little confusing for newbies, especially when they are not familiar with optical chateristics that have a direct impact on the results.

    KB, I sugget looking up topics like 'characteristics of wide, normal and telephoto lenses', 'camera lens basics', 'understanding photography lenses', or the lens section of any 'beginner's guide to photography'.

    Forget about crop sensors etc for now, and just get yourself familiar with

    - lenses and their characteristics,
    - apeture,
    - depth-of-field,
    - angle of view or field of view etc etc etc.

    There are more in-depth areas but I don't suggest you get into those yet until you're totaly familiar with the basics. With a firm foundation in the basics, understanding more complex areas (when you need, or want to) becomes a logical step forward, instead of drowning in deep waters.

  11. #11
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    Default Re: EF lens on EF-S body

    Quote Originally Posted by sk.images View Post
    This is NOT correct.

    What you see is a cropped image from a 50mm lens. The crop will be equivalent to what you would see with an 80mm (approx) lens on FF. BUT, all the characteristics of the 50mm lens will still be apparent (except minor changes to DOF). Lens characteristics (except DOF, which is affected by more then just the lens)are NOT affected by a 'cropped' sensor.
    So if i am using a 50mm lens on a crop body which is about 80mm(approx) and lets say a 80mm lens on a FF body with the same F stop what would be the difference in the DOF?

    and the other question on whether EF-s lens 18-55mm is the actual focal length or do i still have to multiple the 1.6x?

  12. #12
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    Default Re: EF lens on EF-S body

    Quote Originally Posted by KBblue View Post
    So if i am using a 50mm lens on a crop body which is about 80mm(approx) and lets say a 80mm lens on a FF body with the same F stop what would be the difference in the DOF?

    and the other question on whether EF-s lens 18-55mm is the actual focal length or do i still have to multiple the 1.6x?
    The 1.6X multiplier applies to EF-S lenses too.
    Canon 80D|Panasonic LX3/LX5
    35f2 IS|50f1.8|85f1.8|12-24f4|18-135f4-5.6 IS|28-75f2.8

  13. #13

    Default Re: EF lens on EF-S body

    Quote Originally Posted by sk.images View Post
    This is NOT correct.

    What you see is a cropped image from a 50mm lens. The crop will be equivalent to what you would see with an 80mm (approx) lens on FF. BUT, all the characteristics of the 50mm lens will still be apparent (except minor changes to DOF). Lens characteristics (except DOF, which is affected by more then just the lens)are NOT affected by a 'cropped' sensor.
    i didnt say the lens gonna behave like the 80mm.

    just the image. ok. phrasing not so good.

  14. #14

    Default Re: EF lens on EF-S body

    Practically -

    Using a 50mm F/1.8 lens on a 1.6x camera
    is like
    using a 80mm F/2.8 lens on a fullframe (35mm) camera.

    ...in terms of field-of-view, depth-of-field and noise characteristics. You do get less vignetting though. Metering (calculation of shutter speed) is still based on the native aperture (F/1.8, etc. ) because the difference in electronics behind.
    Last edited by grantyale; 12th December 2007 at 02:52 PM.

  15. #15

    Default Re: EF lens on EF-S body

    Quote Originally Posted by KBblue View Post
    So if i am using an EF-s lens, say the 18-55mm kit lens, is that the actual focal length or does the 1.6x factor still applies???
    Would like to know this too. I think the 1.6x still applies right?

  16. #16

    Default Re: EF lens on EF-S body

    Oh yes , the 1.6x crop applies for your 18-55 kit lens as well.

  17. #17

    Default Re: EF lens on EF-S body

    Lets take for example a EF 28-105mm on a full frame, it would be 28mm but it is 38mm equvilant on a 400D.

    Now lets take for example a EFS 17-50mm, 17mm x 1.6 = 28mm so its equivilant to a 28mm on a full frame to counter the 1.6 crop factor.

    EFS lenses are there to help counter the crop factor of the sensors to get the same range you used to get on a flim. As you can see you need a 17mm on a 400D to see the same as a 28mm on a full frame.

    When you crop factor, just take it as taking a picture then cutting out the sides, the lens character does not change whatsoever. Though your sides of your picture will be sharper than using on a full frame because the closer to the center of the lens, the sharper your picture

  18. #18

    Default Re: EF lens on EF-S body

    Quote Originally Posted by electrobeat View Post
    Oh yes , the 1.6x crop applies for your 18-55 kit lens as well.
    Thanks that clears it. simple and good

  19. #19
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    Default Re: EF lens on EF-S body

    i think i got a much better idea now thanks a lot really cleared up

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