Need explanation on "Extended Zoom" in Lumix FZ18

Discussion in 'Panasonic Lumix' started by aniramca, Sep 14, 2008.

  1. aniramca

    aniramca Guest

    I owned the camera over a year now, but have just learned to use it
    recently (after reading the instruction manual)
    I have some questions which I hope someone can provide answers in
    "layman terms".
    What is exactly the extended zoom feature in Lumix FZ18? Is this
    still considered as "optical" zoom. I assume that this is not "digital
    zoom" (because FZ18 still have 4x digital zoom on top of the 18x
    It appears that this option has something to do with reducing the
    resolution for the sake of getting more optical zoom feature. Could
    someone explain in simple terms? How this affect the picture quality,
    in particular if I usually only print photos to max 5"x7" sizes. Most
    of the time it will be postcard size of 3.5"x5".
    The manual said that the FZ 18 has a 18x optical zoom feature
    (equivalent to 18mm to 504 mm). This is however based on picture size
    equivalent to 8 MP (for 4:3 ratio). However, if I select the
    resolution to only 5MP, I can zoom in to 23x. If I choose resolution
    3MP, I can zoom into 28.7x.
    8 MP is equivalent to 3264x2448 pixels, 5 MP is 2560x1920 pixels, and
    3MP is 2048x1536 pixels (for aspect ratio 4:3).
    What do you need to print 5"x7" size photo, 8"x10" and 11"x17"? Is
    3MP good enough for 8"x10" photo? 5"x7"? I know that my computer is
    only set to 1024x768 resolution.
    If this is the case, I can just set my camera to 3MP and enjoy a 28.7x
    zoom ( from 28 mm to 804mm)! I am still assuming this is NOT digital
    Could someone comment on this? Thanks

    Is feature of "extended zoom" in Lumix is common for other long zoom
    P&S cameras (such as Olympus SP570UZ, Fuji S8100fd, or Sony DSC H50)?
    I do not recall that My Canon G7 has this feature (but I may be wrong,
    as I also still have not looked in details into their instruction

    Thanks for info.
    aniramca, Sep 14, 2008
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  2. aniramca

    tony cooper Guest

    This might come across as a non-answer, but it really isn't. Your
    real question is "Can I get a decent picture when I'm in the extended
    zoom range?". The answer is: Take some shots at the maximum optical
    zoom range, and then some shots of the same scene at the maximum
    extended zoom range, print them as 3.5" x 5"s, and compare the
    results. Use something like a child's face as the target. Then crop
    the image taken in the extended zoom to the same area as the image
    taken using only the optical zoom range. Compare all three.

    The shots taken in the extended zoom range will be less sharp, but if
    you don't see that reduction in sharpness, it doesn't matter. Using
    the print sizes you've listed, you probably won't notice the

    If you would submit those three images to some critics with a good
    eye, they'll see the difference. However, if these are family
    photographs for your own use, and you don't see the difference, then
    use the extended zoom whenever you think it might make a better
    tony cooper, Sep 14, 2008
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  3. aniramca

    DavidM Guest

    In extended zoom, the camera is using the lens at it's maximum focal
    length, with no digital magnification/zoom. So in theory it is still
    "optical" zoom with no reduction in resolution of the subject.

    The files that the camera saves in extended 5MP, 3MP, etc are exactly
    the same image that it would save if set to 8MP-standard, however, it
    will have been cropped in-camera to show only the centre. That is why
    the image you view looks more magnified, when infact it's just the
    central region of an 8MP image. Ultimately, you would be better off
    saving at 8MP and cropping it in a photo editor for the desired detail.

    When cropping the image you can look at it's final pixel dimensions and
    judge what size to print it at. There is not really any point in
    printing photos at more than 300 dpi, unless you view them with a
    magnifying glass. (I submit scientific images for publication, and the
    journals ask for 500 dpi. Scientists do use magnifying glasses to view
    them.) Divide the image dimensions of your photo by 300 to see how many
    inches it will reasonably print at.
    For example, the 3MP images at 2048x1536 should be fine for 6.8"x5.12" etc.

    I don't use my fz18 in extended mode, I prefer to crop the original 8MP
    images. It can be handy if you are using the device as a telescope
    though :), but not as a camera.
    Hope that helps.
    DavidM, Sep 15, 2008
  4. observed
    I have an FZ50 which has a similar 'extended zoom'. I assume the FZ18 is

    I have spent a significant amount of time experimenting with the
    differences between 'extended zoom' and 'digital zoom' settings and
    comparing notes with others on the dpreview panasonic group.

    Firstly there is NO improvement in quality between either 'extra xoom'
    method and cropping from the centre of the highest resolution image.

    AIUI, the 'extended zoom' merely crops the centre of the higher
    resolution image to a smaller resolution (which is why you can't use it
    and retain the highest resolution).

    The 'digital zoom', however, takes the centre cropped image and
    interpolates pixels to 'fill it out' to the given resolution as defined.

    I find extended zoom useful in nature photography (eg. birds in flight,
    see: where the
    exposure is - I think - based upon what the camera sees, rather than the
    whole area, and, of course, the EZ images take up less space on the
    memory card.

    Other than that, I can find no particular advantage in using it. Because
    of the 'added processing' of 'digital zoom', I never use it!

    I would suggest that in general the only advantage of either 'zoom'
    facility is for those who have their images printed commercially and do
    not wish to do any post processing of their own.



    [The reply-to address is valid for 30 days from this posting]
    Michael J Davis
    Some newsgroup contributors appear to have confused
    the meaning of "discussion" with "digression".
    Michael J Davis, Sep 15, 2008
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