end of zoom on my lense = bad

Discussion in 'Photography Equipment & Products' started by jwsciontc, Jan 28, 2009.

  1. jwsciontc

    jwsciontc TPF Noob!

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    So i got the Canon 18-200mm for christmas. Now i love the lense, the wide angles are great and remains great quality all through the zoom range. Except, the last 50mm or so, the increase in zoom is so minimal, you wouldnt know it was zoomed in more unless i told you. Are all zoom lenses like this?
     
  2. tirediron

    tirediron Watch the Birdy! Staff Member Supporting Member

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    I'm not sure I follow; are you saying that from 150 to 200mm there is little apparent increase in FL, or from 18-68mm?
     
  3. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    Think of it in terms of percentages. When you zoom from 18mm to 36mm, that's a 100% increase. But when you zoom from 150mm to 200mm, that's only a 33% increase.
     
  4. jwsciontc

    jwsciontc TPF Noob!

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    ahhh is that how it works? cause when i was using it after i noticed, i would go from say 18 to 80 thats roughly 60mm. But then if i would go from 140mmish, to full zoom at 200mm, it is very minimal. Is percentages how it works though?
     
  5. bdavis

    bdavis TPF Noob!

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    I've got a tamron 18-200 for my D90 and it's the same deal, there is so much zoom in the beginning, but the last increments on the lens jump from 100-200 and I barely notice a difference. I'd imagine the only way to remedy this is getting a new lens that doesn't cover such a broad range
     
  6. Slaphead

    Slaphead TPF Noob!

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    Yeah, Nikon 18-200 same thing.

    From what I can gather with these IF superzooms you'll only get the full 200mm when focused at infinity - the closer the subject the less focal length you'll get. From what I've read the Nikon can drop to 110mm effective when focused real close.

    This is apparently due to the internal focusing element changing the focal length as it focuses. Rough example:- at infinity the focus element has moved all the way back hence you get the full 200mm. Close up the focus element is all the way forward hence reducing the effective focal length to around 110 (on the nikon at least).

    I believe this happens with all lenses that employ an internal focusing system, it's just that with these superzooms the effect is greatly exaggerated because the focusing needs to operate over such a wide range of focal lengths.

    I'm only repeating what I've read here so treat it as if KR had written it.
     

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