Learning about lenses

Discussion in 'Beyond the Basics' started by HoboSyke, Jun 26, 2005.

  1. HoboSyke

    HoboSyke TPF Noob!

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    Hey guys.

    As im upgrading to a DSLR soon I need to get upto speed with everything to do with SLR photography.
    When a lense says eg. 18-55mm on it. Does the 18 part mean that thats how far from the sensor the lense starts, and the 55mm part means that the lense is 55mm long ?

    It may seem like a dumb question but since im about to buy a DSLR I need to be equiped with the right knowlege and be able to make a more informed purchase.

    Any other useful info about lenses would also help a great deal..

    Thanks everyone.. :thumbup:
     
  2. etaf

    etaf TPF Noob!

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    its the focal length of the lens and 18mm is a wide angle and 55mm is a normal view
    theres some online courses for photography you may want to have a look at
    http://www.dpforums.com/forum/showthread.php?t=1543
    http://www.dpforums.com/forum/showthread.php?t=1533

    you will also need to understand a little about apertures etc and this may help

    what camera do you have now - perhaps we could help with comparing with a camera you actually have

    what photography do you intend to do? - this may also help us advise
    whats your budget to spend?
    what DSLR are you considering at the moment?
     
  3. HoboSyke

    HoboSyke TPF Noob!

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    Ok, IM getting a Canon 20D.. I want to do a variety of photography.
    Ill need a macro lense, a Zoom lense and a multi purpose lense for potraits and other normal shots.

    Im spending about 5 or 6 thousands AU dollars..
     
  4. HoboSyke

    HoboSyke TPF Noob!

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    Forgot to mention im already using a Camera : Sony Cybershot DSC-F707 Digital.
     
  5. etaf

    etaf TPF Noob!

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    based on this info http://www.steves-digicams.com/2001_reviews/f707.html
    =9.7 - 48.5 mm 38-190mm (35mm equivalent)
    so that camera has a fast lens F2/2.4 and a 35mm equivalent range of 38-190mm

    you will have to pay a lot to get F2/2.4 rang in DSLR lenses
    Now the 20D has a camera factor of x1.6 factor - so any 35mm lenses you will need to multiply the focal length by 1.6 to get an equivalent.
    Macro Canon have a few lenses 60mm and 100mm
    for general purpose you are looking to get something like 35mm equivalent 28mm - 135mm
    for a zoom range perhaps 75mm to 300mm

    Now all that is in 35mm equivalent
    If you notice the kit lens on the 20D is 18 -55mm which in 35mm equivalent is
    18 x 1.6 = 28.8
    55 x 1.6 = 88
    so wider than your 38mm and 28m is good for wideange landscapes or if confined in rooms or streets.
    the 88mm is a lot less than the 190mm you have so zooming in will be a lot less


    some report that this lens is soft and recommend the 17 - 40mm "L" lens
    17 x 1.6 = 27mm
    40 x 1.6 = 64mm

    70-200mm f2.8mm http://www.the-digital-picture.com/Reviews/Canon-EF-70-200mm-f-2.8-L-USM-Lens-Review.aspx

    17-40mm f4 http://www.the-digital-picture.com/Reviews/Canon-EF-17-40mm-f-4.0-L-USM-Lens-Review.aspx


    but that does leave a gap from 40mm to 70mm and those lenses are expensive
    EDIT:
    to fill the gap 24-70 2.8L also a 50mm 1.8 is a great prime lens to have


    theres an awful lot of inforamation on the canon forum
    http://photography-on-the.net/

    as you are spending an lot of money, i would recommend reading those online info
     
  6. etaf

    etaf TPF Noob!

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  7. DocFrankenstein

    DocFrankenstein Clinically Insane?

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    Just get the kit 18-55 lens and take some pictures. then get 50/1.8 lens...

    Once you use them both, you'll get a feel as to what you need/want.

    Or if you have extra 600 bucks, get 14-40 f/4 L lens from the beginning and you'll save 40 bucks or so. ;)

    Wishful thinking.
     
  8. HoboSyke

    HoboSyke TPF Noob!

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    Im still having trouble understanding lenses. Grrrr..
     
  9. John the Greek

    John the Greek TPF Noob!

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    There's not that much to it really, until you start getting lens models with loads of abbreviations and numbers, but that's more technical stuff, here's the basics.

    Lenses are usually first designated by their focal length, which gives you a sense of the field of view offered by the lens.
    12mm-28mm cover the wide angle focal lengths, these give LOTS of coverage and are usually used for landscape photography. They widen the depth of field effectively making things look "flatter" as well.
    35mm, 50mm, and up to...around 80 or so covers the more "normal" fields of view, dubbed normal cause its most similar to what our own eyes cover. A 50mm lens is sometimes called a "normal" lens on its own. These lenses can be used in a wide variety of ways, its recommended that you begin photography with one of these type of lenses.
    80mm and above are called telephoto lenses. These are high magnification that covers a narrow field of view since they bring the subject so close-up. These are ideal for widelife photography, sports photography, and any situation where you want the subject to really stand out. These have a narrow depth of field, which draws in the subject.

    Now other than that there are some more specialized lenses like a fish eye lens, which covers an extreme wide-angle, from 6mm-12mm, they can cover a full 180 degrees or even more. These produce a circular image that looks kind of cool, but in my opinion, are mostly gimmicky.
    I don't know much about macro lenses, anyway.... its really late and I gotta get to sleep.
     
  10. Aoide

    Aoide TPF Noob!

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    HoboSkye,

    I have found what DocFrankenstein said to be completely true. I was having a hard time understanding this aspect of the lenses, but as soon as I had a chance to play with the included kit lens, it all locked into place.
     
  11. HoboSyke

    HoboSyke TPF Noob!

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    Thanks for the help guys.
     

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