Realationship of 200 mm lens to point and shoot camera _X

Discussion in 'Digital SLR' started by Jerry Buseck, Jun 18, 2008.

  1. Jerry Buseck

    Jerry Buseck Guest

    Does anyone know what a 200 mm lens is equal to in a point and shoot
    camera, like what _X power?

    Jerry
     
    Jerry Buseck, Jun 18, 2008
    #1
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  2. Jerry Buseck

    Don R. Guest

    Depends upon the wide end of the lens. The long end is a multiplier of the
    wide end. 30mm to 90mm is a 3x. 30mm to a 180mm is a 6x.
     
    Don R., Jun 18, 2008
    #2
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  3. Jerry Buseck

    Paul Furman Guest

    _X zoom is not the same as _X power. If you really want a number, divide
    50 into 200, so 4x as used with binoculars but it's really not stated
    that way for cameras. With binoculars 1x is if things looked the same as
    your bare eyes but with a camera the size according to your eyes isn't
    relevant, rather the size as it appears on a print. If you hold an 8x10
    print in front of your face shot at 50mm isn't going to look roughly the
    same as your bare eyes... that'll vary how close you like to examine and
    how big the print is, etc. That's why the term isn't used for cameras
    because 50mm isn't a magic number.

    Now.... the 200mm you are asking about is 35mm equivalent focal length.
    Small P&S cameras vary in size but tend to be closer to 1/4 the size of
    35mm film format so your 200mm is probably actually closer to 50mm :)
    and a 'normal' (1x power) lens for that format is more like 12mm.

    --
    Paul Furman
    www.edgehill.net
    www.baynatives.com

    all google groups messages filtered due to spam
     
    Paul Furman, Jun 18, 2008
    #3
  4. Jerry Buseck

    Paul Furman Guest

    TYPO... should read:

    If you hold an 8x10 print in front of your face [which was] shot at
    50mm, [it's] going to look roughly the same as your bare eyes...


    --
    Paul Furman
    www.edgehill.net
    www.baynatives.com

    all google groups messages filtered due to spam
     
    Paul Furman, Jun 18, 2008
    #4
  5. No, not without some more information about what you mean by equal and
    what specific cameras or at least sensors you are talking about.
    Do you mean magnification factor? Again, that depends on the camera
    resp. the sensor size. On a full frame a 200mm lens has a magnification
    factor of about 4, on a DX of about 6.

    jue
     
    Jürgen Exner, Jun 19, 2008
    #5
  6. It's equivalent to "200mm (35mm eauivalent)".

    -Wolfgang
     
    Wolfgang Weisselberg, Jun 19, 2008
    #6
  7. Jerry Buseck

    Frankster Guest

    A 200mm lens is equal to a 200mm lens on any camera.

    What you really seem to be asking is how would a 200mm lens fiels of view
    compare when used with different formats. But you only specify one format
    (point-n-shoot). What do you want to compare it to? Also, specifying
    point-n-shoot alone is not very descriptive either, since there are varying
    formats for them too. But I guess we can assume small for them (sensor
    size).

    -Frank
     
    Frankster, Jun 19, 2008
    #7
  8. Jerry Buseck

    Frankster Guest

    Going on the assumption that you mean compared to full frame 35mm film (like
    most digital lenses are compared), on a point-n-shoot it would be approx
    equivalent to a 400mm on a 35mm format camera (i.e. 2x). Most of today's
    SLRs use a 1.5x equivalency (i.e. 1.5x200 equals 300mm equivalent on a 35mm
    format camera).

    -Frank
     
    Frankster, Jun 19, 2008
    #8
  9. Jerry Buseck

    Jerry Buseck Guest

    Just for comparison, I'm looking at a Canon Power Shot SX100 IS
    it is 8 megapixel a 1/2.5 inch CCD and 10X optical zoom.
    Does the 10X optical zoom acually equal 10X the image size?

    I'm using a Canon EOS Digital Rebel XTI
    Using a 200mm lens which is equal to a 300mm in 35 mm format.
    Would the 200mm lens be 6x optical zoom equal to 6X the image size?
     
    Jerry Buseck, Jun 19, 2008
    #9
  10. You seem to be thourougly confused. Don't despair, you are not alone.

    The zoom factor like e.g. the 10X you mentioned above is simply the
    longest focal lengt divided by the shortest focal length of that lens.
    It could be 10mm-100mm or 20mm-200mm or 100mm-1000mm. All of those
    lenses would be a 10x zoom.
    The zoom factor does not tell you anyting about the magnification (or
    tele) factor. That can be expressed in e.g. 8x, too. This is commonly
    used in e.g. binoculars where 7x is a common marine magnification, 8x or
    10x a common terrestial magnification, and 15x a strong glass for e.g.
    bird viewing. For photography however it is much more common to use the
    focal length. Problem is that the magnification not only depends on the
    focal length but also on the sensor size.

    On a full-frame sensor a focal length of 50mm is considered a 'normal
    lens'. A 200mm lens would have a 4x magnification, a 1000mm lens a 20x
    magnification.
    For a DX sensors you have to adjust the magnification factor for the
    smaller sensor size by a factor of 1.5 or 1.6, depending on the actual
    camera.

    Ok, going back to your original question: a 200mm lens on a DX body
    (Canon EOS Digital Rebel XTI) will have a magnification(!) factor of
    200/50*1.5 = 6x.
    And it will have a zoom(!) factor of 1 because is is not a zoom lens to
    begin with.

    If it were e.g. a 50-200mm lens, then the magnification factor would be
    1.5x - 6x and the zoom factor 4x on a DX body.
    On a full frame camera this lens would have a magnification factor of
    1x-4x and still the same zoom factor of 4x.

    Oh, one more note: neither the camera nor the lens determines the image
    size. The image size only depends on how you print it.

    jue
     
    Jürgen Exner, Jun 19, 2008
    #10
  11. Jerry Buseck

    Jerry Buseck Guest

    OK, I have it now. Thanks for your patience and your help.
     
    Jerry Buseck, Jun 19, 2008
    #11
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