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Thread: EF and EF-S question

  1. #1

    Default EF and EF-S question

    I am very new to DSLR, previously using compact, just started stepping into DSLR world, kind of lost, wish to have some basic understanding,
    read through the newbie corner, but cannot find any info on the below explaination.


    Example:
    EF-S 18-55mm f3.5-5.6 IS (currently using this kit lens)
    EF-S 18-200mm f3.5-5.6 IS
    EF-S 17-85mm f4.0-5.6 IS USM

    EF 24-105mm f4L IS USM
    EF 28-135mm f3.5-5.6 IS USM
    EF 28-200mm f3.5-5.6 USM


    Base on the above examples?
    1) What is the difference between EF and EF-S lens?

    2) what is the ??-??mm number means, eg 18-55mm?

    3) what is the f number means, eg f3.5-5.6?

    4) Which has better wide angle?

    5 if we talk about 28-200mm, what is the equivalent zoom range to those compact digital camera, is it 5x zoom?



    many thanks in advance.

  2. #2
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    Default Re: EF and EF-S question

    Hello Takengo,
    I thought of helping out on your questions:-
    Thanks to you, I learned a bit more on it too.

    1. Difference is pure cosmetic. http://www.slrphotographyguide.com/c...EFS-lens.shtml

    2. Also known as focal length. http://www.dpreview.com/learn/?/key=focal+length

    3. aperture (how wide your lens will opened. F3.5 will opens wider than F10.) http://www.photoxels.com/tutorial_aperture.html

    4. Not too sure on this but I think the shorter the focal length (usually <24mm) the wider the view will be.

    5. Not too sure on this either.

    Perhaps some of the sifu here can share more.
    Cheers.

  3. #3

    Default Re: EF and EF-S question

    Are you sure you couldn't find it? It's all in the Photography-related FAQ thread, and it's all been asked here before, so any SEARCH would have found it.

    For number 5, the "zoom" value in compacts is misleading. All lenses with a variable focal length have a "zoom" of max tele/min tele. So a 28-200 is a 7x zoom. but so is a 10-70. And a 100-700.
    Alpha

  4. #4

    Smile Re: EF and EF-S question

    Quote Originally Posted by wahsehman View Post
    Hello Takengo,
    I thought of helping out on your questions:-
    Thanks to you, I learned a bit more on it too.

    1. Difference is pure cosmetic. http://www.slrphotographyguide.com/c...EFS-lens.shtml

    2. Also known as focal length. http://www.dpreview.com/learn/?/key=focal+length

    3. aperture (how wide your lens will opened. F3.5 will opens wider than F10.) http://www.photoxels.com/tutorial_aperture.html

    4. Not too sure on this but I think the shorter the focal length (usually <24mm) the wider the view will be.

    5. Not too sure on this either.

    Perhaps some of the sifu here can share more.
    Cheers.
    thanks bro,

    that is great info, especially 1 and 2. Now i know what is focal length and difference between EF and EF-S.
    for point 1, I also follow the sub links to learn about other info in the related article, very useful. thanks.

    but for point 3(aperture), i just cannot open the link, i think the link is block in my office, need to try it at home.

  5. #5
    Member Sispecho's Avatar
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    Default Re: EF and EF-S question

    1) EF and EF-S difference NOT only cosmetic. EF-S lens are made with the digital crop sensor in mind, so u can use the for any Digital SLR EXCEPT for 1D and 5D series, where the sensor is bigger than the others. This means that if u use this lens on them (or film SLRs) you will get a severe, hard vignetting on the sensor (meaning your rectangle picture will have black stuff on the corners or sides), and may i add Could cause damage to the mirror (its been speculated but i never tried) if used on 5D and 1D.

    2)thats the focal length. where the lower the number, the wider the perspective is. However, for Canon Digital Cameras (other than 5D or 1D), the effective focal length would be a multiply of '1.6'. For example if u use a 10mm lens on a canon Digital SLR, what u get is actually 16mm perspective, because 10x1.6=16mm. for 5d the multiply factor is 1 (since its sensor size is similar to film '35mm format'-the one u normally buy at mama shop) while the 1D is a bit smaller than the 5d at a multiply of 1.3

    3) the numbers are values of the f stop where they can open up the largest at the extreme ends of the focal length. for eg, 18-200mm f3.5-5.6 means at 18mm the biggest/widest aperture is at f3.5, while at 200mm the biggest and widest it could go is at f5.6. To shoot in low light, at faster shutter speeds or to get blackground blur with relative ease u might want to consider a wider an aperture as possible, meaning lower f stop value.

    4) the widest angle is the one with the lowest focal length value, and among the ones u listed, its the 17-85 at 17mm.

    5) refer to rashkae's answer above.
    Last edited by Sispecho; 30th November 2009 at 04:19 PM.

  6. #6

    Default Re: EF and EF-S question

    Quote Originally Posted by Rashkae View Post
    Are you sure you couldn't find it? It's all in the Photography-related FAQ thread, and it's all been asked here before, so any SEARCH would have found it.

    For number 5, the "zoom" value in compacts is misleading. All lenses with a variable focal length have a "zoom" of max tele/min tele. So a 28-200 is a 7x zoom. but so is a 10-70. And a 100-700.
    i read that, but i cannot absorb their explaination, maybe my English is poor. Bro wahsehman links explains clearly with pictures.

  7. #7

    Default Re: EF and EF-S question

    Quote Originally Posted by Sispecho View Post
    1) EF and EF-S difference NOT only cosmetic. EF-S lens are made with the digital crop sensor in mind, so u can use the for any Digital SLR EXCEPT for 1D and 5D series, where the sensor is bigger than the others. This means that if u use this lens on them (or film SLRs) you will get a severe, hard vignetting on the sensor (meaning your rectangle picture will have black stuff on the corners or sides), and may i add Could cause damage to the mirror (its been speculated but i never tried) if used on 5D and 1D.

    2)thats the focal length. where the lower the number, the wider the perspective is. However, for Canon Digital Cameras (other than 5D or 1D), the effective focal length would be a multiply of '1.6'. For example if u use a 10mm lens on a canon Digital SLR, what u get is actually 16mm perspective, because 10x1.6=16mm. for 5d the multiply factor is 1 (since its sensor size is similar to film '35mm format'-the one u normally buy at mama shop) while the 1D is a bit smaller than the 5d at a multiply of 1.3

    3) the numbers are values of the f stop where they can open up the largest at the extreme ends of the focal length. for eg, 18-200mm f3.5-5.6 means at 18mm the biggest/widest aperture is at f3.5, while at 200mm the biggest and widest it could go is at f5.6. To shoot in low light, at faster shutter speeds or to get blackground blur with relative ease u might want to consider a wider an aperture as possible, meaning lower f stop value.

    4) the widest angle is the one with the lowest focal length value, and among the ones u listed, its the 17-85 at 17mm.

    5) refer to rashkae's answer above.
    thanks bro, you have explained point 3, i have a question, the f number is refering to how big the hole opens at the Lens right, correct me if i am wrong.
    can i say f4 opens bigger hole than f3.5, hence can take wider angle?

  8. #8

    Default Re: EF and EF-S question

    Quote Originally Posted by takengo2003 View Post
    i read that, but i cannot absorb their explaination, maybe my English is poor. Bro wahsehman links explains clearly with pictures.
    That's because number 5 is a pure maths question. No pictures needed. It's primary 1 or primary 2 maths.

    Take ANY non-prime lens, and you can calculate the "zoom". For example, most 18-55 kit lenses are 3x zoom. (55/18).

    A 75-300 lens is a 4x zoom. (300/75).

    A 18-250 lens is a 14x zoom (250/18)
    Alpha

  9. #9

    Default Re: EF and EF-S question

    Quote Originally Posted by Rashkae View Post
    Are you sure you couldn't find it? It's all in the Photography-related FAQ thread, and it's all been asked here before, so any SEARCH would have found it.

    For number 5, the "zoom" value in compacts is misleading. All lenses with a variable focal length have a "zoom" of max tele/min tele. So a 28-200 is a 7x zoom. but so is a 10-70. And a 100-700.
    thanks for explaining on point 5, you guys are great in making me understand the terms.
    Last edited by takengo2003; 30th November 2009 at 04:41 PM.

  10. #10
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    Default Re: EF and EF-S question

    Quote Originally Posted by takengo2003 View Post
    thanks bro, you have explained point 3, i have a question, the f number is refering to how big the hole opens at the Lens right, correct me if i am wrong.
    can i say f4 opens bigger hole than f3.5, hence can take wider angle?
    nope i guess you are wrong. To have the lens 'hole' (aperture) open wider, u need the smallest fnumber. eg. f1.2 the 'hole' opens up bigger than f4 or f3.5. So the bigger the hole, the more light that can go in. So with big 'hole' u can get good background blur easier, and also at the same time have faster shutter speed to 'freeze' motion if compared to 'small hole' lens. Aperture/hole/f-stop dont determine how wide you can take just how big the 'hole' can open.

    To get the wider angle, get a focal length that has smaller number. 17mm is wider than 50mm. you want more 'zoom in' (telephoto) then go get something with higher focal length.

  11. #11

    Smile Re: EF and EF-S question

    Quote Originally Posted by Rashkae View Post
    That's because number 5 is a pure maths question. No pictures needed. It's primary 1 or primary 2 maths.

    Take ANY non-prime lens, and you can calculate the "zoom". For example, most 18-55 kit lenses are 3x zoom. (55/18).

    A 75-300 lens is a 4x zoom. (300/75).

    A 18-250 lens is a 14x zoom (250/18)
    sorry, paiseh, did not know the calculation is done in this way until today.

  12. #12

    Default Re: EF and EF-S question

    Quote Originally Posted by Sispecho View Post
    nope i guess you are wrong. To have the lens 'hole' (aperture) open wider, u need the smallest fnumber. eg. f1.2 the 'hole' opens up bigger than f4 or f3.5. So the bigger the hole, the more light that can go in. So with big 'hole' u can get good background blur easier, and also at the same time have faster shutter speed to 'freeze' motion if compared to 'small hole' lens. Aperture/hole/f-stop dont determine how wide you can take just how big the 'hole' can open.
    so the F number is for how much light to enter the hole, the smaller the f number, hole opens bigger, hence more light can enter right? so if i were to take picture intentionally with blur background, i should set the f number small, am i right?


    Quote Originally Posted by Sispecho View Post
    To get the wider angle, get a focal length that has smaller number. 17mm is wider than 50mm. you want more 'zoom in' (telephoto) then go get something with higher focal length.
    ok, this one i know.

  13. #13
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    Default Re: EF and EF-S question

    Quote Originally Posted by takengo2003 View Post
    so the F number is for how much light to enter the hole, the smaller the f number, hole opens bigger, hence more light can enter right? so if i were to take picture intentionally with blur background, i should set the f number small, am i right?




    ok, this one i know.
    yes, youre right well done. and remember also, to get bokeh (blur background), it also depends on the distance subject to you (nearer better), how far the background is (the further the better) and also the focal length (the more telephoto the better). telephoto meaning focal length bigger than 50mm.

  14. #14

    Default Re: EF and EF-S question

    Another question, take for example the below 2 example, rightfully at 18mm it should give a wider angle than the 28mm, but what if both lens we zoom to the max at 200mm, will both get the same wideness?

    Example:
    EF-S 18-200mm f3.5-5.6 IS
    EF 28-200mm f3.5-5.6 USM

  15. #15

    Default Re: EF and EF-S question

    Quote Originally Posted by takengo2003 View Post
    sorry, paiseh, did not know the calculation is done in this way until today.
    An easy example... Take the Sony HX1:

    http://www.dpreview.com/reviews/spec...ony_dschx1.asp

    It says it has a "20x" zoom lens. So let's do the maths.

    At wide-angle, the lens has a 35mm equivalent of 28mm. On the tele end, it's a 35mm equiv. of 560mm. So yup, 20x.

    But the REAL focal length is 5-100mm. Still 20x though.
    Alpha

  16. #16

    Default Re: EF and EF-S question

    Quote Originally Posted by takengo2003 View Post
    Another question, take for example the below 2 example, rightfully at 18mm it should give a wider angle than the 28mm, but what if both lens we zoom to the max at 200mm, will both get the same wideness?

    Example:
    EF-S 18-200mm f3.5-5.6 IS
    EF 28-200mm f3.5-5.6 USM
    Yes. 200mm = 200mm.
    Alpha

  17. #17

    Default Re: EF and EF-S question

    I can imagine this thread will go back and forth many times, with explanations and further questions So I'd suggest, takengo2003, you read up on the basics -- there's one right at the top of the Newbies page (http://www.clubsnap.com/forums/showthread.php?t=309544)

    Also, to add on to the EF and EF-S lens differences, do note that some crop sensor Canon DSLRs (D30, D60 & 10D) cannot take EF-S lenses. Probably not an issue -- they are pretty old models.

  18. #18

    Default Re: EF and EF-S question

    Quote Originally Posted by Sispecho View Post
    yes, youre right well done. and remember also, to get bokeh (blur background), it also depends on the distance subject to you (nearer better), how far the background is (the further the better) and also the focal length (the more telephoto the better). telephoto meaning focal length bigger than 50mm.
    WRONG.

    Bokeh is the *quality* of the background blur. You cannot "get bokeh". Bokeh is an inherent quality of the lens.

    So the correct statement (ignoring grammar) is:

    "yes, youre right well done. and remember also, to get blur background, it also depends on the distance subject to you (nearer better)"
    Alpha

  19. #19
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    Default Re: EF and EF-S question

    Quote Originally Posted by Rashkae View Post
    WRONG.

    Bokeh is the *quality* of the background blur. You cannot "get bokeh". Bokeh is an inherent quality of the lens.

    So the correct statement (ignoring grammar) is:

    "yes, youre right well done. and remember also, to get blur background, it also depends on the distance subject to you (nearer better)"

    ok ure right. i ignored a technicality there.

  20. #20

    Default Re: EF and EF-S question

    Quote Originally Posted by Sispecho View Post
    ok ure right. i ignored a technicality there.
    Just making sure we teach the right things to newbies...
    Alpha

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