Nikon S10 - zoom range less than claimed?

Discussion in 'Nikon' started by Marty Fremen, Nov 19, 2007.

  1. Marty Fremen

    Marty Fremen Guest

    I've just been trying out a Nikon S10 compact which is stated to have a
    6.3-63mm 10x optical zoom, equivalent to 38-380mm on a 35mm camera.

    I calculate that this should give 5 degrees diagonal view at the long end,
    with a field of view of roughly 30x40cm at 6 metres. Instead I get approx
    40x55 cm field of view at that distance. I also did a comparison of the
    field of view against another camera which has a 72mm lens, and the Nikon
    gives a fraction over 4x magnification to the 72mm lens, making it about
    295mm, which agrees with the field of view measurment. I conclude that the
    Nikon S10 falls a long way short of the claimed 380mm.

    Furthermore comparison of an object viewed at the wide end and the tele end
    reveals a 9x zoom range, not 10x. The EXIF data however reports 38mm and
    380mm for the images at each end of the zoom.

    The question is, do I have a defective sample or are all Nikon S10's like
    this? I can find no mention in any reviews of a mis-represented zoom range
    but nor do I see any mention of anyone actually checking the focal length.
    If anyone has one of these cameras, perhaps you could check whether your
    lens is the same.
     
    Marty Fremen, Nov 19, 2007
    #1
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  2. Marty Fremen

    Marty Fremen Guest

    "David J Taylor"
    Thanks for the comments. I have now reviewed my calculation and
    discovered that I made a mistake in each of the ways I calculated the
    focal length, unfortunately although the mistakes are quite different
    they introduced errors of approx. the same magnitude into each
    calculation, so that the results seemed to agree with each other.

    In my comparison to the 72mm lens I was pixel counting the distance
    between two trees on the horizon in a pair of images and overlooked the
    fact that the 72mm lens camera had a higher resolution image, so each
    pixel subtended a smaller angle than on the S10 image. Correcting for
    this gives a revised focal length of 382mm w.r.t the 72mm lens.

    In my FOV calculation meanwhile I was using the opposite/adjacent=tangent
    trig formula, treating the lens view as a right angled triangle for this.
    But in fact I should have divided it into two half-fov right angle
    triangles, either side of the centre line. I hadn't realised this would
    make a significant difference but in fact it makes a big difference: about
    20%! Redoing my calculation correctly gives a bigger field of view for a
    380mm lens which is much closer to the one I was actually seeing.

    As an aside though, this suggests that my old SLR's zoom lens must be
    longer than the stated 200mm since it was giving the smaller fov
    suggested by my erroneous calculations. Either that or (perhaps more
    likely) the crop factor of my old SLRs viewfinder system is much greater
    than I had previously thought. It was partly the striking difference in
    fov between my old zoom with 2x converter (=400mm) and the S10's 380mm
    lens which convinced me that the S10 was nowhere near 380mm.
     
    Marty Fremen, Nov 21, 2007
    #2
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