Nikon wide angle lense question - confused on one aspect

Discussion in 'Digital Photography' started by DeanB, Jun 21, 2007.

  1. DeanB

    DeanB Guest

    I don't understand this:

    http://www.nikonusa.com/template.php?cat=1&grp=5

    Why is it the 14mm lense has a 114 degree FOV, while the 16mm has a
    full 180? Is there something special about fisheye lenses (the 16mm in
    this case) vs. non-fisheye?

    Thanks for any insight!

    Dean
    DeanB, Jun 21, 2007
    #1
    1. Advertising

  2. On Jun 21, 8:24 am, DeanB <> wrote:
    > I don't understand this:
    >
    > http://www.nikonusa.com/template.php?cat=1&grp=5
    >
    > Why is it the 14mm lense has a 114 degree FOV, while the 16mm has a
    > full 180? Is there something special about fisheye lenses (the 16mm in
    > this case) vs. non-fisheye?
    >
    > Thanks for any insight!
    >
    > Dean


    Indeed, when we get to extreme fisheyes, the idea of focal length
    controlling field of view breaks down. In order to truly get 180
    degree FOV with conventional optics, it would take zero focal length,
    which is of course impossible. So extreme fisheye lenses MUST have
    distortion. Effectively, the focal length is not constant with field
    angle. That "distortion" gives the field of view at the more extreme
    field angles.
    Don Stauffer in Minnesota, Jun 21, 2007
    #2
    1. Advertising

  3. DeanB

    dj_nme Guest

    Don Stauffer in Minnesota wrote:
    > On Jun 21, 8:24 am, DeanB <> wrote:
    >
    >>I don't understand this:
    >>
    >>http://www.nikonusa.com/template.php?cat=1&grp=5
    >>
    >>Why is it the 14mm lense has a 114 degree FOV, while the 16mm has a
    >>full 180? Is there something special about fisheye lenses (the 16mm in
    >>this case) vs. non-fisheye?
    >>
    >>Thanks for any insight!
    >>
    >>Dean

    >
    >
    > Indeed, when we get to extreme fisheyes, the idea of focal length
    > controlling field of view breaks down. In order to truly get 180
    > degree FOV with conventional optics, it would take zero focal length,
    > which is of course impossible. So extreme fisheye lenses MUST have
    > distortion. Effectively, the focal length is not constant with field
    > angle. That "distortion" gives the field of view at the more extreme
    > field angles.


    One other possibility is that the 14mm f/2.8D ED AF isn't a full frame
    lens, as this isn't specifically mentioned in the description for this lens.
    The 16mm f/2.8D AF Fisheye-Nikkor is specifically described as having
    "Full frame 180 degree fisheye coverage...", so I can only guess from
    this that it will definitely cover the whole 24x36mm 135 film frame.
    Another possible reason for the 14mm f/2.8D ED AF not being as "wide" as
    the 16mm lens is that it might be a rectilinear (distortion corrected) lens.
    This tends to "stretch out" the edges of the image to make objects
    appear the same size at the same distance regardless of how off-axis it
    is and make the angular coverage less than a non-rectilinear lens.

    I don't have either lens and can't do anything other than speculate.

    Perhaps looking through pbase.com for images tagged as being made with
    these lenses will answer this aspect of the question?
    dj_nme, Jun 21, 2007
    #3
  4. "dj_nme" <> wrote in message news:467a91bb$0$22433$...
    > Don Stauffer in Minnesota wrote:
    >> On Jun 21, 8:24 am, DeanB <> wrote:


    >>>I don't understand this:
    >>> http://www.nikonusa.com/template.php?cat=1&grp=5
    >>>
    >>>Why is it the 14mm lense has a 114 degree FOV, while the 16mm has a
    >>>full 180? Is there something special about fisheye lenses (the 16mm in
    >>>this case) vs. non-fisheye?


    There are various types of perspectives (rectangular, spherical,
    orthographic, one best approximated with very long telephotos
    [as in old Chinese/Japanese paintings and drawings of buildings
    made without perspective effects], etc.). In all, made by all lenses,
    the focal lengths are rated similarly (by the distance of the lens
    optical center from the sensor at infinity focus) - but the perspective
    types (and distortions within the perspective types caused by lens
    design shortcomings) may cause straight lines of subjects running
    off axis of the image center (of an unshifted lens relative to the
    sensor) to be curved, which causes a shift in image magnification
    away from the center of the image, sometimes permitting a greater
    angle of view to be photographed using some lens perspective
    types. Or, a truly "distortion-free" rectangular-perspective type
    of lens will show the same magnification in the center as a truly
    "distortion-free" spherical-perspective type of lens of the same
    FL, but as you look away from the image center, the fisheye will
    show increasingly less subject magnification, and therefore more
    included subject area (a greater angle of view).

    >> Indeed, when we get to extreme fisheyes, the idea of focal length
    >> controlling field of view breaks down.


    Not really - see above...

    >> In order to truly get 180
    >> degree FOV with conventional optics, it would take zero focal length,
    >> which is of course impossible. So extreme fisheye lenses MUST have
    >> distortion.


    Not "distortion", but a different set of perspective rules - see above...

    >> Effectively, the focal length is not constant with field
    >> angle. That "distortion" gives the field of view at the more extreme
    >> field angles.


    > One other possibility is that the 14mm f/2.8D ED AF isn't a full frame lens, as this isn't specifically mentioned in the
    > description for this lens.


    It is full-frame...

    > The 16mm f/2.8D AF Fisheye-Nikkor is specifically described as having "Full frame 180 degree fisheye coverage...", so I can only
    > guess from this that it will definitely cover the whole 24x36mm 135 film frame.


    It will...

    > Another possible reason for the 14mm f/2.8D ED AF not being as "wide" as the 16mm lens is that it might be a rectilinear
    > (distortion corrected) lens.
    > This tends to "stretch out" the edges of the image to make objects appear the same size at the same distance regardless of how
    > off-axis it is and make the angular coverage less than a non-rectilinear lens.


    Ah, close - but it doesn't really "stretch-out" the image edges. Try
    a pinhole camera - it renders perfect rectangular perspective, but has
    no optics to "stretch" things...;-)

    > I don't have either lens and can't do anything other than speculate.
    >
    > Perhaps looking through pbase.com for images tagged as being made with these lenses will answer this aspect of the question?


    See above...;-) I also have an article, "On Seeing and Perspective" on
    my web page, at www.donferrario.com/ruether/articles.html#perspective
    in which I try to explain how we see, and in which perspective type (it
    may surprise you, but it is easy to prove...;-).
    --
    David Ruether

    http://www.donferrario.com/ruether
    David Ruether, Jun 21, 2007
    #4
  5. David Ruether, Jun 21, 2007
    #5
  6. DeanB

    ink Guest

    "dj_nme" <> wrote in message
    news:467a91bb$0$22433$...
    > Don Stauffer in Minnesota wrote:
    >> On Jun 21, 8:24 am, DeanB <> wrote:
    >>
    >>>I don't understand this:
    >>>
    >>>http://www.nikonusa.com/template.php?cat=1&grp=5
    >>>
    >>>Why is it the 14mm lense has a 114 degree FOV, while the 16mm has a
    >>>full 180? Is there something special about fisheye lenses (the 16mm in
    >>>this case) vs. non-fisheye?
    >>>
    >>>Thanks for any insight!
    >>>
    >>>Dean

    <SNIP>
    > Another possible reason for the 14mm f/2.8D ED AF not being as "wide" as
    > the 16mm lens is that it might be a rectilinear (distortion corrected)
    > lens.


    The 14mm is indeed rectilinear.

    Cheers,
    ink
    ink, Jun 21, 2007
    #6
  7. "David Ruether" <> wrote in message news:f5e78m$9jm$...
    >
    >
    > "DeanB" <> wrote in message news:...
    >
    >>I don't understand this:
    >> http://www.nikonusa.com/template.php?cat=1&grp=5
    >>
    >> Why is it the 14mm lense has a 114 degree FOV, while the 16mm has a
    >> full 180? Is there something special about fisheye lenses (the 16mm in
    >> this case) vs. non-fisheye?

    >
    > See my post below...


    Oooops! Shoulda been, "above"...;-)
    But it got me thinking - and I will probably add an article on my web
    page next to "On Seeing and Perspective" called "On Lenses and
    Perspective Types" (at www.donferrario.com/ruether/articles.html).
    --
    David Ruether

    http://www.donferrario.com/ruether
    David Ruether, Jun 21, 2007
    #7
  8. In article <f5e78m$9jm$>,
    David Ruether <> wrote:
    >
    >
    >"DeanB" <> wrote in message news:...
    >
    >>I don't understand this:
    >> http://www.nikonusa.com/template.php?cat=1&grp=5
    >>
    >> Why is it the 14mm lense has a 114 degree FOV, while the 16mm has a
    >> full 180? Is there something special about fisheye lenses (the 16mm in
    >> this case) vs. non-fisheye?

    >
    >See my post below...


    Do you know if there is standard formula for fisheyes?

    For rectilinear lenses it is easy: just imagine a pinhole at the focal
    length distance of the sensor, and you can compute the projection.

    For fisheyes, I never found an obvious way to translate focal length into
    field of view.


    --
    That was it. Done. The faulty Monk was turned out into the desert where it
    could believe what it liked, including the idea that it had been hard done
    by. It was allowed to keep its horse, since horses were so cheap to make.
    -- Douglas Adams in Dirk Gently's Holistic Detective Agency
    Philip Homburg, Jun 21, 2007
    #8
  9. DeanB

    Jim Guest

    "Philip Homburg" <> wrote in message
    news:234vdj2s5fr9tgsp7idlgv4ip4@inews_id.stereo.hq.phicoh.net...
    > In article <f5e78m$9jm$>,
    > David Ruether <> wrote:
    >>
    >>
    >>"DeanB" <> wrote in message
    >>news:...
    >>
    >>>I don't understand this:
    >>> http://www.nikonusa.com/template.php?cat=1&grp=5
    >>>
    >>> Why is it the 14mm lense has a 114 degree FOV, while the 16mm has a
    >>> full 180? Is there something special about fisheye lenses (the 16mm in
    >>> this case) vs. non-fisheye?

    >>
    >>See my post below...

    >
    > Do you know if there is standard formula for fisheyes?
    >
    > For rectilinear lenses it is easy: just imagine a pinhole at the focal
    > length distance of the sensor, and you can compute the projection.
    >
    > For fisheyes, I never found an obvious way to translate focal length into
    > field of view.
    >
    >
    > --
    > That was it. Done. The faulty Monk was turned out into the desert where it
    > could believe what it liked, including the idea that it had been hard done
    > by. It was allowed to keep its horse, since horses were so cheap to make.
    > -- Douglas Adams in Dirk Gently's Holistic Detective Agency


    Doesn't a fish-eye lens really have a very large amount of pincushion
    distortion?
    It looks to me like computing the angle of view is not such a simple task.
    Jim
    Jim, Jun 22, 2007
    #9
  10. DeanB

    dj_nme Guest

    ink wrote:
    > "dj_nme" <> wrote in message
    > news:467a91bb$0$22433$...
    >
    >>Don Stauffer in Minnesota wrote:
    >>
    >>>On Jun 21, 8:24 am, DeanB <> wrote:
    >>>
    >>>
    >>>>I don't understand this:
    >>>>
    >>>>http://www.nikonusa.com/template.php?cat=1&grp=5
    >>>>
    >>>>Why is it the 14mm lense has a 114 degree FOV, while the 16mm has a
    >>>>full 180? Is there something special about fisheye lenses (the 16mm in
    >>>>this case) vs. non-fisheye?
    >>>>
    >>>>Thanks for any insight!
    >>>>
    >>>>Dean

    >
    > <SNIP>
    >
    >>Another possible reason for the 14mm f/2.8D ED AF not being as "wide" as
    >>the 16mm lens is that it might be a rectilinear (distortion corrected)
    >>lens.

    >
    >
    > The 14mm is indeed rectilinear.
    >
    > Cheers,
    > ink


    I'm surprised that Nikon doesn't mention this on their website, it seems
    like an oversight on their part.
    dj_nme, Jun 22, 2007
    #10
  11. "Jim" <> wrote in message news:rvFei.3232$...
    > "Philip Homburg" <> wrote in message news:234vdj2s5fr9tgsp7idlgv4ip4@inews_id.stereo.hq.phicoh.net...
    >> In article <f5e78m$9jm$>,
    >> David Ruether <> wrote:
    >>>"DeanB" <> wrote in message news:...


    >>>>I don't understand this:
    >>>> http://www.nikonusa.com/template.php?cat=1&grp=5
    >>>>
    >>>> Why is it the 14mm lense has a 114 degree FOV, while the 16mm has a
    >>>> full 180? Is there something special about fisheye lenses (the 16mm in
    >>>> this case) vs. non-fisheye?


    >>>See my post [above...]


    >> Do you know if there is standard formula for fisheyes?


    There must be, but I don't know what it would be - though Nikon
    made two FF fisheye designs, both rated as 16mm. One covers
    180 degrees, but the other covers 170 degrees (maybe due to
    inaccuracies in FL rating?). Some other mfgrs. rate their FF 35mm
    fisheyes as 15mm lenses. I think technically the spherical perspective
    type may be defined as one in which as the lens is rotated, identical
    subject elements at the same distance from the lens are rendered
    the same size in the middle of the image...

    >> For rectilinear lenses it is easy: just imagine a pinhole at the focal
    >> length distance of the sensor, and you can compute the projection.
    >>
    >> For fisheyes, I never found an obvious way to translate focal length into
    >> field of view.


    See above for a possibility, though optical designs could easily
    introduce slight variations on it...

    > Doesn't a fish-eye lens really have a very large amount of pincushion distortion?


    I think you meant "barrel"...;-)

    > It looks to me like computing the angle of view is not such a simple task.
    > Jim


    Probably not hard if the lens designer designed a true spherical
    perspective lens - but impossible otherwise...;-)
    --
    David Ruether

    http://www.donferrario.com/ruether
    David Ruether, Jun 22, 2007
    #11

  12. > Do you know if there is standard formula for fisheyes?
    >
    > For rectilinear lenses it is easy: just imagine a pinhole at the focal
    > length distance of the sensor, and you can compute the projection.
    >
    > For fisheyes, I never found an obvious way to translate focal length into
    > field of view.


    But to get true 180 degrees the pinhole would have to be of infinitely
    thin material. That is, the length of the pinhole itself must be
    zero, i.e., zero thickness aperture stop (pinhole) material. For a
    true rectilinear lens the extreme field ray leaves the pinhole
    PARALLEL to the aperture stop plane (the material the pinhole is in).
    Thus unless the format size is infinite, the focal length (distance
    between pinhole/stop) and focal plane must be ZERO.
    Don Stauffer in Minnesota, Jun 22, 2007
    #12
  13. On Jun 21, 8:22 pm, "Jim" <> wrote:
    >
    > Doesn't a fish-eye lens really have a very large amount of pincushion
    > distortion?
    > It looks to me like computing the angle of view is not such a simple task.
    > Jim


    Indeed, it MUST. Otherwise either the focal length must be zero or
    the format size infinite. Now, distortion is a variation in focal
    length with field angle. In a true 180 degree lens the focal length
    must change from whatever it is at small field angles to zero as the
    field angle approaches 90 degrees.
    Don Stauffer in Minnesota, Jun 22, 2007
    #13
  14. DeanB

    dj_nme Guest

    Don Stauffer in Minnesota wrote:
    >>Do you know if there is standard formula for fisheyes?
    >>
    >>For rectilinear lenses it is easy: just imagine a pinhole at the focal
    >>length distance of the sensor, and you can compute the projection.
    >>
    >>For fisheyes, I never found an obvious way to translate focal length into
    >>field of view.

    >
    >
    > But to get true 180 degrees the pinhole would have to be of infinitely
    > thin material. That is, the length of the pinhole itself must be
    > zero, i.e., zero thickness aperture stop (pinhole) material. For a
    > true rectilinear lens the extreme field ray leaves the pinhole
    > PARALLEL to the aperture stop plane (the material the pinhole is in).
    > Thus unless the format size is infinite, the focal length (distance
    > between pinhole/stop) and focal plane must be ZERO.


    In practice, it isn't possible to have a 180 degree field of view captured.
    It's possible to get very close, by curving the film plane (for example
    into a semi-circle) so that the ends are very close to the panel with
    the pinhole in it.
    Something like this (excuse the ascii art):

    /pinhole
    /
    V
    _________________ _________________
    * *
    * *
    ** **
    ** **
    *** ***
    *** ***
    **** **** <---film
    ***

    I don't know what the image would look like when developed and printed,
    perhaps distorted like a fisheye lens would make?
    dj_nme, Jun 22, 2007
    #14
  15. "Don Stauffer in Minnesota" <> wrote in message news:...
    > On Jun 21, 8:22 pm, "Jim" <> wrote:


    >> Doesn't a fish-eye lens really have a very large amount of pincushion
    >> distortion? ["barrel" and "distortion" - both I think are incorrect...]
    >> It looks to me like computing the angle of view is not such a simple task.
    >> Jim


    > Indeed, it MUST. Otherwise either the focal length must be zero or
    > the format size infinite. Now, distortion is a variation in focal
    > length with field angle.


    Only if you recognize as "correct" the perspective type "rectangular",
    and then apply its rules to fisheyes - but there are other perspective
    types that are correct (spherical, orthographic, isometric, etc.), and
    lenses that accurately follow these are not "distorted"...

    > In a true 180 degree lens the focal length
    > must change from whatever it is at small field angles to zero as the
    > field angle approaches 90 degrees.


    This cannot be true, since that would indicate that there could be
    no discernable detail (zero magnification of image parts at 180
    degrees...), and one can easily see detail at the edge of coverage
    of lenses that cover 180 degrees (or even more, like the 6.2mm
    Nikkor, with 220 degrees of coverage).
    --
    David Ruether

    http://www.donferrario.com/ruether
    David Ruether, Jun 22, 2007
    #15
  16. Re: Nikon wide angle lens question - confused on one aspect

    "dj_nme" <> wrote in message news:467bdbe5$0$22423$...
    > Don Stauffer in Minnesota wrote:


    >>>Do you know if there is standard formula for fisheyes?
    >>>
    >>>For rectilinear lenses it is easy: just imagine a pinhole at the focal
    >>>length distance of the sensor, and you can compute the projection.
    >>>
    >>>For fisheyes, I never found an obvious way to translate focal length into
    >>>field of view.


    >> But to get true 180 degrees the pinhole would have to be of infinitely
    >> thin material. That is, the length of the pinhole itself must be
    >> zero, i.e., zero thickness aperture stop (pinhole) material. For a
    >> true rectilinear lens the extreme field ray leaves the pinhole
    >> PARALLEL to the aperture stop plane (the material the pinhole is in).
    >> Thus unless the format size is infinite, the focal length (distance
    >> between pinhole/stop) and focal plane must be ZERO.


    There is also the matter of rapid illumination roll-off away from the
    image center that makes super-wide flat sensor pinhole cameras
    impractical (but, see below...).

    > In practice, it isn't possible to have a 180 degree field of view captured.
    > It's possible to get very close, by curving the film plane (for example into a **semi-circle**) so that the ends are very close to
    > the panel with the pinhole in it.
    > Something like this (excuse the ascii art):
    >
    > /pinhole
    > /
    > V
    > _________________ _________________
    > * *
    > * *
    > ** **
    > ** **
    > *** ***
    > **** **** <---film
    > I don't know what the image would look like when developed and printed, perhaps distorted like a
    > fisheye lens would make?


    It is easy to imagine (and I used to shoot paper in a camera like this,
    but I added a single glass lens element taped behind the pinhole - it
    appeared to improve image quality some) if you have ever seen images
    taken with a camera with a rotating lens. BTW, this adds one more
    perspective type, "cylindrical"...;-)
    --
    David Ruether

    http://www.donferrario.com/ruether
    David Ruether, Jun 22, 2007
    #16
  17. Re: Nikon wide angle lens question - confused on one aspect

    [This is a rewriting of my response after rethinking parts of it.]

    "dj_nme" <> wrote in message news:467a91bb$0$22433$...

    > Don Stauffer in Minnesota wrote:
    >> On Jun 21, 8:24 am, DeanB <> wrote:


    >>>I don't understand this:
    >>> http://www.nikonusa.com/template.php?cat=1&grp=5
    >>>
    >>>Why is it the 14mm lense has a 114 degree FOV, while the 16mm has a
    >>>full 180? Is there something special about fisheye lenses (the 16mm in
    >>>this case) vs. non-fisheye?




    There are various types of perspectives (rectangular, spherical,

    orthographic, reverse-spherical, cylindrical, isometric (one best

    approximated with very long telephotos, as in old Japanese

    paintings and drawings of buildings made without perspective

    effects), etc. In all, made by all lenses, the focal lengths are rated

    similarly (by the distance of the lens optical center from the

    sensor at infinity focus) - but the perspective types (and distortions

    within the perspective types caused by lens design shortcomings)

    may cause straight lines of subjects running off axis of the image

    center (of an unshifted lens relative to the sensor) to be curved,

    which causes a shift in image magnification away from the center

    of the image, sometimes permitting a greater angle of view to be

    photographed using some lens perspective types. Or, a truly

    "distortion-free" rectangular-perspective type of lens will show

    the same magnification in the center as a truly "distortion-free"

    spherical-perspective type of lens (fisheye) of the same FL, but

    as you look away from the image center, the fisheye will show

    increasingly less subject magnification, and therefore more

    included subject area (a greater angle of view).



    >> Indeed, when we get to extreme fisheyes, the idea of focal length
    >> controlling field of view breaks down.




    Not really - see above...



    >> In order to truly get 180
    >> degree FOV with conventional optics, it would take zero focal length,
    >> which is of course impossible. So extreme fisheye lenses MUST have
    >> distortion.




    Not "distortion", but a different set of perspective rules - see above...



    >> Effectively, the focal length is not constant with field
    >> angle. That "distortion" gives the field of view at the more extreme
    >> field angles.


    > One other possibility is that the 14mm f/2.8D ED AF isn't a full frame lens, as this isn't specifically mentioned in the
    > description for this lens.




    It is full-frame...


    > The 16mm f/2.8D AF Fisheye-Nikkor is specifically described as having "Full frame 180 degree fisheye coverage...", so I can only
    > guess from this that it will definitely cover the whole 24x36mm 135 film frame.




    It will...


    > Another possible reason for the 14mm f/2.8D ED AF not being as "wide" as the 16mm lens is that it might be a rectilinear
    > (distortion corrected) lens.
    > This tends to "stretch out" the edges of the image to make objects appear the same size at the same distance regardless of how
    > off-axis it is and make the angular coverage less than a non-rectilinear lens.




    Ah, close - but it doesn't really "stretch-out" the image edges. Try

    a pinhole camera - it renders perfect rectangular perspective, but has

    no optics to "stretch" things...;-)


    > I don't have either lens and can't do anything other than speculate.
    >
    > Perhaps looking through pbase.com for images tagged as being made with these lenses will answer this aspect of the question?




    See above...;-) I also have an article, "On Seeing and Perspective" on

    my web page, at www.donferrario.com/ruether/articles.html#perspective

    in which I try to explain how we see, and in which perspective type (it

    may surprise you, but it is easy to prove that we see in spherical

    perspective...;-).
    --
    David Ruether

    http://www.donferrario.com/ruether
    David Ruether, Jun 22, 2007
    #17
  18. Re: Nikon wide angle lens question - confused on one aspect

    I just put up below - "On Lenses and Perspective Types" - this
    should answer this and other posts in this thread (and even more...;-)
    --
    David Ruether

    http://www.donferrario.com/ruether


    "DeanB" <> wrote in message news:...
    >I don't understand this:
    >
    > http://www.nikonusa.com/template.php?cat=1&grp=5
    >
    > Why is it the 14mm lense has a 114 degree FOV, while the 16mm has a
    > full 180? Is there something special about fisheye lenses (the 16mm in
    > this case) vs. non-fisheye?
    >
    > Thanks for any insight!
    >
    > Dean
    David Ruether, Jun 22, 2007
    #18
  19. David Ruether, Jun 23, 2007
    #19
  20. DeanB

    dj_nme Guest

    Re: Nikon wide angle lens question - confused on one aspect

    David Ruether wrote:

    > "dj_nme" <> wrote in message news:467bdbe5$0$22423$...

    <snip>
    >>In practice, it isn't possible to have a 180 degree field of view captured.
    >>It's possible to get very close, by curving the film plane (for example
    >>into a **semi-circle**) so that the ends are very close to the panel with
    >>the pinhole in it.
    >>Something like this (excuse the ascii art):
    >>
    >> /pinhole
    >> /
    >> V
    >> _________________ _________________
    >> * *
    >> * *
    >> ** **
    >> ** **
    >> *** ***
    >> **** **** <---film
    >> *********
    >>I don't know what the image would look like when developed and printed,
    >>perhaps distorted like a fisheye lens would make?

    >
    > It is easy to imagine (and I used to shoot paper in a camera like this,
    > but I added a single glass lens element taped behind the pinhole - it
    > appeared to improve image quality some) if you have ever seen images
    > taken with a camera with a rotating lens. BTW, this adds one more
    > perspective type, "cylindrical"...;-)


    How did you orient the extra lens and how did it effect the image?
    dj_nme, Jun 23, 2007
    #20
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