Digital Camera Crops and 0.7x Teleconverters

Discussion in 'Digital Photography' started by Vin, Oct 29, 2003.

  1. Vin

    Vin Guest

    Hi,

    Just had an idea. Why hasn't anyone come up with
    a teleconverter which reduces a full frame image
    down to a 1.5 or 1.6 crop. Sort of like what those
    older Nikon DSLRs did in the body.

    Say we had a 0.7x (1/1.4x) converter. If the image
    reduced by 1.4 times, then you would gain 1 whole
    stop as well since we are concentrating it on
    half the area.

    Wouldn't this work theoretically? if we had
    perfect glass that didnt give distortion or
    chormatic abberations, this would work, would
    it not? Could we keep infinity focus on
    something like this?

    Just my thoughts anyway. If it could be built
    at the same price as the other OEM Teleconverters
    (or even twice, it better have decent glass in it),
    it would still beats paying for a current full
    frame DSLR.

    Vin.
    --
    Vin
    Melbourne, Australia
    Remove no and spam from both sides of the @ sign email address to reply
     
    Vin, Oct 29, 2003
    #1
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  2. Vin

    NJH Guest

    "Vin" <> wrote in message
    news:9sfnnb.8q2.ln@192.168.11.2...
    > Hi,
    >
    > Just had an idea. Why hasn't anyone come up with
    > a teleconverter which reduces a full frame image
    > down to a 1.5 or 1.6 crop. Sort of like what those
    > older Nikon DSLRs did in the body.


    That would be an anti-teleconverter. :)


    >
    > Say we had a 0.7x (1/1.4x) converter. If the image
    > reduced by 1.4 times, then you would gain 1 whole
    > stop as well since we are concentrating it on
    > half the area.
    >
    > Wouldn't this work theoretically? if we had
    > perfect glass that didnt give distortion or
    > chormatic abberations, this would work, would
    > it not? Could we keep infinity focus on
    > something like this?


    I shouldn't think keeping infinity focus would be a problem for an
    anti-teleconverter, since teleconverters do it without difficulty.

    Your idea is certainly intriguing. There may be something wrong with it, but
    I can't think of what it might be. Since a 1.4x converter loses you a stop,
    it does seem reasonable that a 0.7x converter would gain you a stop, and
    doing away with that pesky multiplier (or most of it) would make the thing
    worthwhile anyway.

    Neil


    >
    > Just my thoughts anyway. If it could be built
    > at the same price as the other OEM Teleconverters
    > (or even twice, it better have decent glass in it),
    > it would still beats paying for a current full
    > frame DSLR.
    >
    > Vin.
    > --
    > Vin
    > Melbourne, Australia
    > Remove no and spam from both sides of the @ sign email address to reply
     
    NJH, Oct 29, 2003
    #2
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  3. Vin

    PhotoMan Guest

    "Vin" <> wrote in message
    news:9sfnnb.8q2.ln@192.168.11.2...
    > Hi,
    >
    > Just had an idea. Why hasn't anyone come up with
    > a teleconverter which reduces a full frame image
    > down to a 1.5 or 1.6 crop. Sort of like what those
    > older Nikon DSLRs did in the body.
    >
    > Say we had a 0.7x (1/1.4x) converter. If the image
    > reduced by 1.4 times, then you would gain 1 whole
    > stop as well since we are concentrating it on
    > half the area.
    >
    > Wouldn't this work theoretically? if we had
    > perfect glass that didnt give distortion or
    > chormatic abberations, this would work, would
    > it not? Could we keep infinity focus on
    > something like this?
    >
    > Just my thoughts anyway. If it could be built
    > at the same price as the other OEM Teleconverters
    > (or even twice, it better have decent glass in it),
    > it would still beats paying for a current full
    > frame DSLR.


    Why not take all the energy and engineering required to produce the item as
    you describe it, and instead make lenses that are actually full frame with
    sensors smaller than 24 X 36 mm?
     
    PhotoMan, Oct 29, 2003
    #3
  4. Vin

    NJH Guest

    "PhotoMan" <> wrote in message
    news:dZPnb.62873$...
    >
    > "Vin" <> wrote in message
    > news:9sfnnb.8q2.ln@192.168.11.2...
    > > Hi,
    > >
    > > Just had an idea. Why hasn't anyone come up with
    > > a teleconverter which reduces a full frame image
    > > down to a 1.5 or 1.6 crop. Sort of like what those
    > > older Nikon DSLRs did in the body.
    > >
    > > Say we had a 0.7x (1/1.4x) converter. If the image
    > > reduced by 1.4 times, then you would gain 1 whole
    > > stop as well since we are concentrating it on
    > > half the area.
    > >
    > > Wouldn't this work theoretically? if we had
    > > perfect glass that didnt give distortion or
    > > chormatic abberations, this would work, would
    > > it not? Could we keep infinity focus on
    > > something like this?
    > >
    > > Just my thoughts anyway. If it could be built
    > > at the same price as the other OEM Teleconverters
    > > (or even twice, it better have decent glass in it),
    > > it would still beats paying for a current full
    > > frame DSLR.

    >
    > Why not take all the energy and engineering required to produce the item

    as
    > you describe it, and instead make lenses that are actually full frame with
    > sensors smaller than 24 X 36 mm?


    Great idea, but there are so many different sizes of sensors. The handy
    thing about lenses for 35mm cameras is that they all are designed to cover
    that 24 x 36 mm, and never any need to redesign 'em for larger or smaller
    formats--which would create a manufacturing and marketing nightmare in the
    case of digital SLRs, I should think.

    Besides, a major attraction to digital SLRs is that they allow the buyer to
    use his existing film SLR lenses--not have to buy a whole new set.

    I don't see why "all the energy and engineering required" should be so much
    anyway, just to design an anti-teleconverter. And it would only have to be
    done ONCE, then all existing lenses could be used.

    Neil
     
    NJH, Oct 29, 2003
    #4
  5. Vin

    Guest

    In message <RoPnb.16720$>,
    "NJH" <> wrote:

    >That would be an anti-teleconverter. :)


    Or a tele-inverter.
    --

    <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
    John P Sheehy <>
    ><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
     
    , Nov 1, 2003
    #5
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