2197mm Zoom f/3.5 Hand-Held Photo on a P&S Camera

Discussion in 'Digital Photography' started by john tallen, Nov 3, 2008.

  1. john tallen

    john tallen Guest

    I've been following the P&S vs. Digital-SLR debates for awhile. I
    thought I'd try what was suggested on an older P&S camera that I
    happened to have laying around for backup purposes. I borrowed a
    tel-extender from a friend to stack it on the one I already had.

    Here's a quick sample of the results of hand held photography with
    good optics, stacked tel-extenders, and a good but inexpensive P&S

    Focal Length (in 35mm equivalent) = 432mm (camera's zoom lens) X 1.76
    (digital zoom) X 1.7 (optical tel-extender) X 1.7 (optical
    tel-extender) =

    2197mm effective focal length with an aperture of f/3.5. Downsized
    only, no cropping, no other editing done.


    For that kind of light grasp at that focal length reach, doing this
    hand held with this much clarity, I say that P&S guy is 100% right.
    For nature photography I can't think of a lighter, smaller, and more
    adaptable kit. You can even see the small drops of drinking-water on
    its beak from as far away as I shot this photo.

    You can keep your digital SLR cameras. I'll be selling mine. Do doubt
    about it.
    john tallen, Nov 3, 2008
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  2. john tallen

    Me Here Guest

    I see a soft image with CA. Pretty crappy image, but if you think it's good
    then be happy. BTW it's not f:3.5 with all that glass and digital zoom
    Me Here, Nov 3, 2008
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  3. We were somewhere around Barstow, on the edge of the desert, when the
    drugs began to take hold. I remember "john tallen"
    Grimly Curmudgeon, Nov 3, 2008
  4. john tallen

    john tallen Guest

    It's interesting that you would see CA in it. The small black and
    white details in the corners of the plastic container show no shifting
    of colors, there's not even any purple fringing from the sensor on the
    bright sunlit portions of the bird. Your comment shows that either
    your monitor or eyes are badly aligned. Do you imagine things because
    you don't want to believe what you see? Yes, the image is a little
    soft but when put through a Fourier-transform sharpener it's quite
    usable from the full-size image. I foresee no problems making 8x10
    prints from the original after sharpening.

    For that price at that aperture at that focal length there's nothing
    at all in the digital SLR camera world that could even come close. And
    it is too f/3.5 with all that glass. P&S cameras do not use the same
    tel-extender method as digital SLRs. Putting a tel-extender on a P&S
    lens is like redesigning the lens and increasing its diameter. If the
    camera and tel-extender glass is of high quality then this is no
    different than buying a whole new high-quality lens that has larger
    components up front. It's like having a modular lens system. If you
    figure the total new aperture and also take into consideration that a
    smaller area of the sensor is being used because a low amount of
    digital-zoom was involved (higher crop-factor to account for that
    focal-length) then it really is an f/3.5 aperture at that focal

    The image was taken in the late afternoon in the far north, low sun
    angle, sunset is at 4:50 pm. With diffuse sunlight diffused further by
    surrounding dense woods. Using the Sunny-16 rule this image would
    require an exposure of about f/4.5 to f/5.6 at ISO100 and 1/100
    shutter speed. It was shot with an exposure of f/3.5, that's 0.6 to
    1.3 stop larger, +EV. ISO200, 1.0 stop larger, +EV. 1/640 shutter, 2.3
    stops lower, -EV. Even without figuring it from lens diameters and
    focal lengths, the exposure settings and subject itself all adds up to
    prove that it is completely acting as an f/3.5 aperture lens. Whether
    you want to believe it or not.

    For those interested in bokeh from P&S cameras the twigs behind the
    bird were about 5 feet away.

    I guess you're all going to have to reconsider what you've convinced
    yourselves of all your lives. I'm doing just that.

    As for as the other person that replied, the only idiots around here
    are the ones that can't do the simple math involved.
    john tallen, Nov 3, 2008
  5. john tallen

    ray Guest

    For starters, you can factor out the 1.76x digital zoom. That is,
    effectively, a simple crop.
    ray, Nov 3, 2008
  6. john tallen

    john tallen Guest

    No, you cannot. That is what defines the FOV, which in turn defines
    the effective focal-length.

    Do you discount the 1.6x crop factor from a DSLR when using a 55mm
    lens when calculating its 35mm equivalent focal length? Digital-zoom
    in effect is just using a smaller central portion of the same sensor.
    That increases the crop-factor. Which in turn increases the 35mm
    equivalent focal-length.

    I see now why the P&S proponent (TrollSpotter?) is having such a
    difficult time with convincing others. If you can't even comprehend
    how simply that this all ties together.
    john tallen, Nov 3, 2008
  7. john tallen

    john tallen Guest

    True. An interesting point to make. However, you might be in error
    about one thing. As far as I know they can't make telescope optics
    with that f-ratio. The amount of coma at that f-ratio makes them unfit
    for imaging. There are a rare few rich-field (wide-field) telescopes
    at that f-ratio but they can't be used for magnified imaging. The best
    they can do is f/4.5 at those sizes of physical apertures. This f/3.5
    aperture at that focal-length is therefore unavailable to any digital
    SLR owner, no matter what cost of telescope that they wish to attach
    to their camera. It can't be done even if they wanted one. What a
    relief. This saves them from having to pay even more for the
    guaranteed chiropractor bills from just one hand-held shot. :) They'd
    better have the foresight too to have had sensor-shift
    image-stabilization. As that too could never be done optically in that
    impossible to make digital SLR lens.
    john tallen, Nov 3, 2008
  8. john tallen

    Pete D Guest

    And one thing to keep in mind is that with this setup sure you will get the
    occasional shot but sadly the delay in focus for P&S setups will mean many
    missed shots compared to pretty much any D-SLR.


    Pete D, Nov 3, 2008
  9. john tallen

    Pete D Guest

    Perhaps you should keep your grammar checker though.

    I for one would be very interested in seeing some more of your shots, do you
    have a link to some more?


    Pete D, Nov 3, 2008
  10. john tallen

    Eric Stevens Guest

    You might find http://www.pbase.com/bm2amb/image/60097051 of interest.

    Eric Stevens
    Eric Stevens, Nov 3, 2008
  11. john tallen

    Eric Stevens Guest

    When it comes to evaluating the optics the 'effective focal length' is
    irrelevant. All that matters is the actual focal length. All this talk
    of 'effective' focal length and 'crop factors' serves to muddle what
    should be simple physics.

    See http://en.wikipedia.org/wiki/Numerical_aperture

    Eric Stevens
    Eric Stevens, Nov 3, 2008
  12. john tallen

    Me Here Guest

    I agree, a 300mm lens is still a 300mm regardless! If I took a photo on film
    ans raised the enlarger up 40% I would get the same result as the APS-C
    sensor. The OP thinks that stacking three supplementary lenses in front
    doesn't affect light transmission, well sorry it does. If he was to measure
    the light, he would see there was some form of "filter factor" with light

    As for his contention his image was sharp, nope it was soft.
    Me Here, Nov 3, 2008
  13. john tallen

    john tallen Guest

    Why should I find that of any interest? Do you want me to carry around
    350 lbs of glass to equal the same focal-length range and apertures as
    can be done with 2 lbs of glass + camera? It's not even hopefully
    equivalent. That 2000mm f/11 lens doesn't have anywhere near the same

    Add in the price too. No, I have no interest whatsoever in that page
    nor anything on it.

    I can see again why that P&S guy is laughing at you people. You don't
    have a clue. It's just all wishful thinking and desperation to justify
    why you choose digital SLRs. Nothing more than that. And that's just
    for optics reasons. Add in those fast shutter speeds he's listed, the
    convenience, etc. Digital SLRs can't even compete with a good P&S
    anymore. You're all just fooling yourselves.
    john tallen, Nov 3, 2008
  14. john tallen

    Pete D Guest

    Hello tom,

    My P&S does not have manual focus. How does this go for moving targets?


    Pete D, Nov 3, 2008
  15. john tallen

    ray Guest

    What you have cited are entirely different effects. A "digital zoom" is,
    effectively a crop - that is all. "Equivalent focal length" matters only
    as it relates to the size of the sensor. The magnification is true focal
    lenth divided by (diagonal) size of the sensor.
    ray, Nov 3, 2008
  16. john tallen

    Eric Stevens Guest

    You should try asking him where he gets his claimed shutter speeds. He
    will never tell you.

    Eric Stevens
    Eric Stevens, Nov 3, 2008
  17. john tallen

    Eric Stevens Guest

    I've never bothered with 'crop factors'. I've always thought in terms
    of focal length and image size. I suppose 'crop factor' is convenient
    for people such as you who seem to have known nothing previously other
    than 35mm cameras, but its irrelevant as far as the optics of the
    situation is concerned.

    Eric Stevens
    Eric Stevens, Nov 3, 2008
  18. john tallen

    Steve Guest

    But you put 2 tele-extenders on it. Are they both the same or does
    the one in front have an appropriatly larger diameter?

    You're also using digital-zoom. I'm not sure why though. You should
    just take the picture without digital zoom and crop for what you want
    in post.
    What I see is an image, the quality of which would cause an editor at
    National Geographic to laugh if you tried to submit it for publishing.
    It's not bad. Just not the quality you can get with a high-end DSLR
    and glass. Of course, for much more expense. As usual, you get what
    you pay for.

    Steve, Nov 3, 2008
  19. JT's Keeper wrote:
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    David J Taylor, Nov 4, 2008
  20. john tallen

    Ray Fischer Guest

    The aperture that he did not actually get?

    Maybe you should account for the fact that stacking on extenders
    affects the maximum aperture. Maybe you should realize that the laws
    of physics apply to P&S cameras as much as they do to SLRs.
    Ray Fischer, Nov 4, 2008
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