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Thread: newbie qns: What are those lens no. for?

  1. #1

    Default newbie qns: What are those lens no. for?

    i very newbie. Need to ask a stupid qns.
    example Lens have 10mm-300mm, what do those numbers stands for?

  2. #2
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    those numbers stand for the focal lengths

    erm, easily put, its the zoom.
    10mm - wide angle
    300mm - zoom

    wait for the experts to get into the technicalities...
    hope it helps

  3. #3

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    Quote Originally Posted by wainism
    those numbers stand for the focal lengths

    erm, easily put, its the zoom.
    10mm - wide angle
    300mm - zoom

    wait for the experts to get into the technicalities...
    hope it helps
    oic....tat means if unzoom = 10mm, so if another lens which is 5mm will have wider angle rite?
    300mm is how much i can zoom rite? The higher the further i can zoom.
    Generally does it oso means that the greater the diff between these 2 nos. the better it is?

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    Moderator ortega's Avatar
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    Generally the greater the diff between the zoom the less lens you need to buy.
    But usually, it also means that the image quality drops.

    The numbers stand for the focal lenght range of the zoom lens.
    There are prime lenses that are fixed focal lenght, e.g 50mm

    The difference in between the numbers is the field of view that you get.
    Lots of information on this on the internet, seek and you will find.

    Don't worry to much about the tech bits,
    shoot first!

    It is better to have a great image of so-so quality that no image at all.

  5. #5

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    Quote Originally Posted by kensh09
    i very newbie. Need to ask a stupid qns.
    example Lens have 10mm-300mm, what do those numbers stands for?
    Briefly its the focal length of the lens which is the distant between the plane of focus to the centre of the lens.

    50mm for the 35mm format is known as the normal lens where the image is supposed to be equal to the size of our vision. Any focal length less than 50mm is known as wide angle and telephoto for range above 50mm.

  6. #6

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    see this for example. take note that angle of view for 1.6x and 1.3x crop cameras are multiplied accordingly. i believe the demo shows angle of view for fullframe cameras.

    http://www.usa.canon.com/html/eflens...gth/index.html

  7. #7

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    Quote Originally Posted by ortega
    Generally the greater the diff between the zoom the less lens you need to buy.
    But usually, it also means that the image quality drops.

    The numbers stand for the focal lenght range of the zoom lens.
    There are prime lenses that are fixed focal lenght, e.g 50mm

    The difference in between the numbers is the field of view that you get.
    Lots of information on this on the internet, seek and you will find.

    Don't worry to much about the tech bits,
    shoot first!

    It is better to have a great image of so-so quality that no image at all.
    Saw some lens tat have fixed focus length. Does it makes the quality better compared to adjustable? Does it oso means that this len can only take picture of a fixed distance?
    Last edited by kensh09; 4th March 2005 at 02:52 PM.

  8. #8

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    not fixed distance (since u can always move about) , but fixed field of view (since the focal length is fixed)

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    Moderator ortega's Avatar
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    Quote Originally Posted by kensh09
    Saw some lens tat have fixed focus length. Does it makes the quality better compared to adjustable? Does it oso means that this len can only take picture of a fixed distance?
    Fixed FOV not fixed distance.
    Normally Fixed FOCAL lenght (not focus) have less moving parts
    so less things to go wrong.
    Quality depends on the lens in question and what it is compaired to.

    Cost of brand new lens from $200 to over $10K

    Read the reviews, I am not an expert.
    Buy the best that you can afford.
    Best is to borrow one and fire away a few rounds, then check with your computer. if you are happy with your picture then buy lah.

  10. #10

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    Quote Originally Posted by kensh09
    Saw some lens tat have fixed focus length. Does it makes the quality better compared to adjustable? Does it oso means that this len can only take picture of a fixed distance?
    Your question was about focal length which has nothing to do with zoom lens and its quality.

    Zoom lens is like having a few lenses of different focal length in one. However, this type of lens are built with more pieces of glass (lens elements). Light are bent when passing through these elements, more elements will mean a higher loss in the details which will result a loss in constrast and sharpness. Too much bending of light will also result in image distortion etc. These short comings are overcome by lens design such as aspherical elements that reduce image distortion, better multi-coating and the use flourite compound for reducing the loss of details. In general its easier to design fixed focal length (or prime) lenses which are usually lesser elements in construction, therefore capable of better resulting image.
    Last edited by litefoot; 4th March 2005 at 04:29 PM.

  11. #11

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    Quote Originally Posted by litefoot
    Your question was about focal length which has nothing to do with zoom lens and its quality.

    Zoom lens is like having a few lenses of different focal length in one. However, this type of lens are built with more pieces of glass (lens elements). Light are bent when passing through these elements, more elements will mean a higher loss in the details which will result a loss in constrast and sharpness. Too much bending of light will also result in image distortion etc. These short comings are overcome by lens design such as aspherical elements that reduce image distortion, better multi-coating and the use flourite compound for reducing the loss of details. In general its easier to design fixed focal length (or prime) lenses which are usually lesser elements in construction, therefore capable of better resulting image.
    oic....now i can understand better.....so a prime lens is a len that had fixed focus lens, means cannot zoom in and out rite. Which oso means if i want a clear picture i have to move my body towards and away from the object, unless zoom lens which can be zoom. Right bo?

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    Quote Originally Posted by kensh09
    oic....now i can understand better.....so a prime lens is a len that had fixed focus lens, means cannot zoom in and out rite. Which oso means if i want a clear picture i have to move my body towards and away from the object, unless zoom lens which can be zoom. Right bo?
    Yo man u almost got it except for that part, You don need to move to get a clear pic, the lens can focus to get clear pics. You only move forwards or backwards to get a narrower or wider field of view. ( further to get wider view, nearer for narrower view but bigger subject.)

    With a zoom lens u can stay where u r and let the lens do the walking for u.

  13. #13

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    Quote Originally Posted by wainism
    those numbers stand for the focal lengths

    erm, easily put, its the zoom.
    10mm - wide angle
    300mm - zoom

    wait for the experts to get into the technicalities...
    hope it helps
    ic... So fisheye len belongs to which caterory ?? How many mm ?
    Or is it a kind of special len ?

  14. #14

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    Quote Originally Posted by obewan
    ic... So fisheye len belongs to which caterory ?? How many mm ?
    Or is it a kind of special len ?

    if there is only one focal length (eg 14mm or 15mm or 16mm), its a prime lens

    if there is a varible focal length, (eg 12-24mm, 10-22mm) its a zoom lens

  15. #15

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    Quote Originally Posted by Dann
    Yo man u almost got it except for that part, You don need to move to get a clear pic, the lens can focus to get clear pics. You only move forwards or backwards to get a narrower or wider field of view. ( further to get wider view, nearer for narrower view but bigger subject.)

    With a zoom lens u can stay where u r and let the lens do the walking for u.
    Not quite. You move to get closer or further from the subject. You cannot change the perspective of a wide angle lens by doing so.

  16. #16

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    Quote Originally Posted by obewan
    ic... So fisheye len belongs to which caterory ?? How many mm ?
    Or is it a kind of special len ?
    Wide angle. Usually less than 10mm.

  17. #17

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    Quote Originally Posted by litefoot
    Wide angle. Usually less than 10mm.
    i thot anything less than 50mm is consider WA?

  18. #18
    Moderator ortega's Avatar
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    Yes anything less that 50mm is considered WA

    He meant that the fish eye belongs to the WA cat
    and that it is usually less than 10mm (not)

    Current Nikon fish eye lenses

    AF DX Fisheye 10.5mm f/2.8G ED
    LIST PRICE : SIN$1310

    AF Fisheye 16mm f/2.8D*
    LIST PRICE : SIN$1330

  19. #19

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    other values like f...lower is better? or wad?

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