EXTREMELY noob question.

Discussion in 'Photography Beginners' Forum' started by Markw, Aug 4, 2008.

  1. Markw

    Markw No longer a newbie, moving up!

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    I googled it 1000x and I always come up with the same things. What does mm mean in lenses? I know what it means, but I guess what Im asking is what can a 400mm lens do over a 50mm lens? Is it a matter of zoom (I doubt it)? How does this impact the size of the lens? I know this sounds extremely newb-ish, but This is the ONE thing that I just cant wrap my head around. Every time I research it, I get elaborate terms and unbelieveably complicated diagrams about DOV and focal range that are just too complicated for me. So, simply put, what can a 400mm lens do that a 50mm lens couldnt do, what situations could it handle that a 50mm couldnt? Things like that is what I want answered. Thanks a bundle.

    Mark
     
  2. midlight21

    midlight21 TPF Noob!

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    mm means millimeter but better to let someone else tell you what it means for lenses....i'm a noob too.
     
  3. AussieDee

    AussieDee TPF Noob!

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    I"m guessing the range of sight. 400mm means it can zoom in at 400mm and a 50mm will only zoom in at 50 millimeters.... ????? 400 is further than 50.

    I"m guessing too. :D
     
  4. rufus5150

    rufus5150 TPF Noob!

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    Heh, someone will probably come along and correct me.... it's the distance, in millimeters, from the lens to the focal point, the sensor of the camera. So if I interpret that correctly, at 50mm, the lens it 50mm away from where the image is recorded. 400mm would be 400mm away (and explains the rather lengthy lenses).

    50mm on a 35mm camera is roughly how the world looks without the camera.

    At 400mm, things are going to seem a whole lot closer.

    Ignore the text, but look at the pictures here: http://en.wikipedia.org/wiki/Photographic_lens#Aperture_and_focal_length

    The 4 pictures labeled 28mm, 50mm, 75mm, and 210mm. They're taken from the same standing position, with lenses at different focal lengths.
     
  5. AussieDee

    AussieDee TPF Noob!

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    So if you wanted to capture wildlife in it's own habitat, so as not to scare the critter, you'd use a 400mm lens - is this correct?

    What about macro shots?
     
  6. rufus5150

    rufus5150 TPF Noob!

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    I'm neither a macro shooter nor a wildlife shooter (2 1/2 year olds aside).

    As far as I know, the macro lenses are engineered to allow a closer minimum focal distance. How that's achieved would be a good question to have answered here from my perspective.

    Almost all of the wildlife photographers I know use either a 300mm or a 70-200mm lens, but none of them are pros.
     
  7. json2001

    json2001 TPF Noob!

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    I've been doing a lot of research on lenses lately and after said research the MM is the focal length in millimeters.

    Macro lenses are their own special animal as far as I understand:
    Just read a nice, easy to understand article last night on Lens basics as well. It cleared up quite a few questions I had on lenses.
     
  8. AussieDee

    AussieDee TPF Noob!

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    I was just guestimating at the 400mm lens thing... roughly that range for wildlife is all. I don't have any lenses. I still use a cheap $99 P&S. :( one day tho. one day.
     
  9. AussieDee

    AussieDee TPF Noob!

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    Excellent read! Thanks for that link! :thumbup:
     
  10. prodigy2k7

    prodigy2k7 No longer a newbie, moving up!

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    mm is the focal length, it is contained inside the lens itself I believe. *NORMALLY* the physically longer lenses, the longer the focal length, and the greater distance you are able to see.

    100x zoom is basically how much the zoom changes...

    10-100mm = 10x zoom
    100-1000mm = 10x zoom

    a "x" zoom doesnt mean a certain distance you can see, you might not get very far at all! It just how much the zoom changes, not how far you can see...
     
  11. KhronoS

    KhronoS TPF Noob!

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    The focal length of the lens is defined as the distance from the middle of the lens to its focal point.

    About the difference between different focal lengths:
    Well a 10mm lens has a small distance between the last element and the image sensor so it give an extreme wide view
    But as the focal length increases the field of view decreases, so thats why you zoom in meaning that at 400mm you have a small field of vie but you zoom in the image.

    More about it:
    http://www.photoaxe.com/understanding-the-lens-focal-length-and-aperture/
    http://en.wikipedia.org/wiki/Focal_length
    Some focal lengths Comparison:
    http://www.tamroneurope.com/flc.htm
     
  12. Markw

    Markw No longer a newbie, moving up!

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    They could not have used a worse structure to demonstrate this on if their life depended on it! I get the general idea but with the mostzoomed in one, you cant even tell where on the structure it is zoomed on. It could be anywhere there and it would make a difference if you knew. Just figured Id point that out.

    Mark
     

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