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Thread: Lens jargon

  1. #1

    Default Lens jargon

    Hi all.

    pardon me but i need to ask this question thats been puzzling me.

    Googling around doesnt help much either as they go very straight into the detail if i type out the following and not answering my question. here it goes:

    Why is it that when talking about camera lens 28mm, 24mm, 21mm, these are talking about wide angle. like 21mm is wider as compared to 24mm.

    But lens that are saying 18-55mm, these are talking about zoom. isnt it like 18mm will be wider and 55mm will be a narrower view?

    If use a 18-55mm, set to 18mm, the pictures taken will be wider than a non-zoom lens of 21mm?

    Thanks for all your kind understanding as I believe this is a super noob question which I believe I had misinterpreted the jargon somewhere also...

  2. #2
    Deregistered rgy1993's Avatar
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    Default Re: Lens jargon

    man i cant wait till all the grumpy people on here find this thread.

    you can expect either one of the following responses:

    "go search it" (oh wait that can't happen anymore HAHA xD )
    "do some research don't expect us to spoonfeed you"
    "aiya why like that is it too hard to look around and find the answer to your question"

    i bid you good luck against the torrent of flame that shall come for you good sir

  3. #3

    Default Re: Lens jargon

    Hi,

    The "mm value is the focal length of the lens. The smaller the focal length, the wider the field of view, hence 28mm and smaller can be called wide angle. Zoom lens states the upper and lower limit of its focal length. And yes, if u use a zoom lens set at 18mm, you get a wider view than a prime lens (non-zoom) at 21mm.

    Cheers!

  4. #4
    Member LexLim's Avatar
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    Default Re: Lens jargon

    Quote Originally Posted by mikeeeey View Post
    Hi all.

    pardon me but i need to ask this question thats been puzzling me.

    Googling around doesnt help much either as they go very straight into the detail if i type out the following and not answering my question. here it goes:

    Why is it that when talking about camera lens 28mm, 24mm, 21mm, these are talking about wide angle. like 21mm is wider as compared to 24mm.

    But lens that are saying 18-55mm, these are talking about zoom. isnt it like 18mm will be wider and 55mm will be a narrower view?

    If use a 18-55mm, set to 18mm, the pictures taken will be wider than a non-zoom lens of 21mm?

    Thanks for all your kind understanding as I believe this is a super noob question which I believe I had misinterpreted the jargon somewhere also...
    I believe 28mm, 24mm, 21mm are wide angle for a full frame camera. Reason why 18-55mm is a zoom lens, is due to its variable focal length, so you can zoom. So zoom lenses =/= lenses which have super high focal length.

    But hey i could be wrong
    Nikon D60|18-55|55-200|105 f/2.5 ai|35 f/1.8|
    My Flickr

  5. #5
    Member LexLim's Avatar
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    Default Re: Lens jargon

    Quote Originally Posted by rgy1993 View Post
    man i cant wait till all the grumpy people on here find this thread.

    you can expect either one of the following responses:

    "go search it" (oh wait that can't happen anymore HAHA xD )
    "do some research don't expect us to spoonfeed you"
    "aiya why like that is it too hard to look around and find the answer to your question"

    i bid you good luck against the torrent of flame that shall come for you good sir
    I AM GRUMPY GRRRRR!
    Nikon D60|18-55|55-200|105 f/2.5 ai|35 f/1.8|
    My Flickr

  6. #6

    Default Re: Lens jargon

    Quote Originally Posted by rgy1993 View Post
    man i cant wait till all the grumpy people on here find this thread.

    you can expect either one of the following responses:

    "go search it" (oh wait that can't happen anymore HAHA xD )
    "do some research don't expect us to spoonfeed you"
    "aiya why like that is it too hard to look around and find the answer to your question"

    i bid you good luck against the torrent of flame that shall come for you good sir
    I was taking 1,201 deep breathes when I hit to Submit Thread button. So yes, I was expecting that. But I believe there are nice people also..

  7. #7

    Default Re: Lens jargon

    Quote Originally Posted by lawrencewkl View Post
    Hi,

    The "mm value is the focal length of the lens. The smaller the focal length, the wider the field of view, hence 28mm and smaller can be called wide angle. Zoom lens states the upper and lower limit of its focal length. And yes, if u use a zoom lens set at 18mm, you get a wider view than a prime lens (non-zoom) at 21mm.

    Cheers!
    Quote Originally Posted by LexLim View Post
    I believe 28mm, 24mm, 21mm are wide angle for a full frame camera. Reason why 18-55mm is a zoom lens, is due to its variable focal length, so you can zoom. So zoom lenses =/= lenses which have super high focal length.

    But hey i could be wrong

    Ahhh.. thanks for the info. It really helps alot.

    I wish to clarify that I do not a own a DSLR or a camera that allow me to change lens. So i do not have personal experience which I can play with. Hence I need to seek help from you nice people that have experience with such lens. Much appreciated.

  8. #8

    Default Re: Lens jargon

    Most Entry/Prosumer DSLRs induces 1.6x "crop factor" onto your lens. So a 18-55mm isn't actually that (in standard '35mm equivalent' measurement terms) when mounted on say a EOS 550D.. In this case, 18mm x 1.6 crop = 28.8mm. Which is actually not very wide, compared to say the 24mm of Panasonic Lumix LX-3. I believe 28mm is usually widest on other compact cameras.

    So first, you'll need to convert the lens specs into 35mm equivalent for an apple to apple comparison. At least that is how i interpret it.

  9. #9
    Senior Member ZerocoolAstra's Avatar
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    Default Re: Lens jargon

    Quote Originally Posted by sk_online View Post
    Most Entry/Prosumer DSLRs induces 1.6x "crop factor" onto your lens. So a 18-55mm isn't actually that (in standard '35mm equivalent' measurement terms) when mounted on say a EOS 550D.. In this case, 18mm x 1.6 crop = 28.8mm. Which is actually not very wide, compared to say the 24mm of Panasonic Lumix LX-3. I believe 28mm is usually widest on other compact cameras.

    So first, you'll need to convert the lens specs into 35mm equivalent for an apple to apple comparison. At least that is how i interpret it.
    you are quite right, but just to clarify the point that an 18-55mm zoom lens has an actual focal length of 18-55mm. That's physics. That's a property of the lens, and nothing to do with the camera.

    The fact that the camera has a "crop factor" is to do with the fact that the sensor is smaller than the ol' 35mm film frame, which was very widely used in the day.
    So the APS-C sized sensor sees a smaller image than 35mm film, sorta like a window within a window, if that makes it any clearer.

    A zoom lens is any lens that has a range of focal lengths made possible with a zoom ring and some complex mechanisms.
    An 18-55mm is a zoom lens.
    An 18-20mm (if there was such a thing) is also a zoom lens.

    If there is only one focal length specified (eg. 50mm), it's known as a prime lens.
    Exploring! :)

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    Default Re: Lens jargon

    Quote Originally Posted by mikeeeey View Post
    ...
    Why is it that when talking about camera lens 28mm, 24mm, 21mm, these are talking about wide angle. like 21mm is wider as compared to 24mm.

    But lens that are saying 18-55mm, these are talking about zoom. isnt it like 18mm will be wider and 55mm will be a narrower view?

    If use a 18-55mm, set to 18mm, the pictures taken will be wider than a non-zoom lens of 21mm?

    ...
    generally, lenses with shorter focal length than 35mm can be said wide angles.. the lenses you have mentioned are wide angles for full frame or 35mm film cameras though they won't be that "wide" when we put them on a DX or APS-C camera..
    if you use 18-55mm lens (a standard zoom for a DX or APS-C camera) at 18mm, it will be 27mm~29mm equivalent.. so a 21mm lens on a FF camera is still wider..
    technical details of physics of optics is not possible to be explained here.. google may be your best partner

  11. #11

    Default Re: Lens jargon

    thanks for all info. need some time to digest the info here.

    Thanks once again...

  12. #12
    Moderator daredevil123's Avatar
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    Default Re: Lens jargon

    Here is a reading on crop factor. Maybe it will help you understand it more. http://www.kenrockwell.com/tech/crop-factor.htm

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