How Sharp Can we go.

Discussion in 'Digital Photography' started by Don, Aug 25, 2004.

  1. Don

    Don Guest

    With the ever increasing Pixel count in Cameras, where is the turning point
    where the top of the line Lenses would be no better than the pixel count.
    From what I have seen allot of the newcomers to DSLRs are already not happy
    about the soft focus on their lenses which shows that the pixel count is
    much better than the Lens they are using. It looks to me that 6 MP was great
    for 90% of the users and now 8MP is good enough for about 98% of the users.
    I still like it to be the Camera for the weak point of the max resoultion
    as we can always change out the lens.
    Don, Aug 25, 2004
    #1
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  2. "Don" <> wrote in news:q71Xc.179971$8_6.120005@attbi_s04:

    > With the ever increasing Pixel count in Cameras, where is the turning
    > point
    > where the top of the line Lenses would be no better than the pixel
    > count. From what I have seen allot of the newcomers to DSLRs are
    > already not happy about the soft focus on their lenses which shows
    > that the pixel count is much better than the Lens they are using. It
    > looks to me that 6 MP was great for 90% of the users and now 8MP is
    > good enough for about 98% of the users.
    > I still like it to be the Camera for the weak point of the max
    > resoultion
    > as we can always change out the lens.
    >


    It is a matter of optimization. If more pixels is cheap, then
    more pixels will not decrease the resolution. It will give
    you some oversampling which will simplify the task to make
    a good anti alias filter. Smaller pixels will add to the noise
    and therefore decrease the ISO sensitivity. Or will it? If you
    have more pixels you don't have to enlarge the pixels so much.


    /Roland
    Roland Karlsson, Aug 25, 2004
    #2
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  3. Don

    jpc Guest

    On 25 Aug 2004 17:59:59 GMT, Roland Karlsson
    <> wrote:

    >"Don" <> wrote in news:q71Xc.179971$8_6.120005@attbi_s04:
    >
    >> With the ever increasing Pixel count in Cameras, where is the turning
    >> point
    >> where the top of the line Lenses would be no better than the pixel
    >> count. From what I have seen allot of the newcomers to DSLRs are
    >> already not happy about the soft focus on their lenses which shows
    >> that the pixel count is much better than the Lens they are using. It
    >> looks to me that 6 MP was great for 90% of the users and now 8MP is
    >> good enough for about 98% of the users.
    >> I still like it to be the Camera for the weak point of the max
    >> resoultion
    >> as we can always change out the lens.
    >>

    >
    >It is a matter of optimization. If more pixels is cheap, then
    >more pixels will not decrease the resolution. It will give
    >you some oversampling which will simplify the task to make
    >a good anti alias filter. Smaller pixels will add to the noise
    >and therefore decrease the ISO sensitivity. Or will it? If you
    >have more pixels you don't have to enlarge the pixels so much.



    The pixels may be smaller, but two side by side pixels that vary by 5
    percent will still vary by 5 percent

    jpc
    >
    >
    >/Roland
    jpc, Aug 25, 2004
    #3
  4. jpc wrote in news::

    > The pixels may be smaller, but two side by side pixels that vary by 5
    > percent will still vary by 5 percent
    >


    Yes - that sounds true - but whats your point?


    /Roland
    Roland Karlsson, Aug 25, 2004
    #4
  5. "Don" <> wrote in message
    news:q71Xc.179971$8_6.120005@attbi_s04...
    > With the ever increasing Pixel count in Cameras, where is the turning

    point
    > where the top of the line Lenses would be no better than the pixel count.
    > From what I have seen allot of the newcomers to DSLRs are already not

    happy
    > about the soft focus on their lenses which shows that the pixel count is
    > much better than the Lens they are using. It looks to me that 6 MP was

    great
    > for 90% of the users and now 8MP is good enough for about 98% of the

    users.
    > I still like it to be the Camera for the weak point of the max

    resoultion
    > as we can always change out the lens.


    ???

    Since when did anyone's photography demand the absolute highest resolution
    of a lens?

    --
    Martin Francis http://www.sixbysix.co.uk
    "Go not to Usenet for counsel, for it will say both no, and yes, and
    no, and yes...."
    Martin Francis, Aug 25, 2004
    #5
  6. Don wrote:
    > With the ever increasing Pixel count in Cameras, where is the turning
    > point where the top of the line Lenses would be no better than the
    > pixel count. From what I have seen allot of the newcomers to DSLRs
    > are already not happy about the soft focus on their lenses which
    > shows that the pixel count is much better than the Lens they are
    > using. It looks to me that 6 MP was great for 90% of the users and
    > now 8MP is good enough for about 98% of the users. I still like it
    > to be the Camera for the weak point of the max resoultion as we can
    > always change out the lens.


    I'd say we're pretty safe in the lens resolution department up to 40 MP or
    so.

    --
    ------------------------------
    online photo portfolio
    www.stojcic.com

    " If you saw a man drowning and you could either save him or photograph
    the event, what film would you use?" - Anonymous
    Drazen Stojcic / BUNTOVNIK, Aug 25, 2004
    #6
  7. Don

    jpc Guest

    On 25 Aug 2004 18:39:50 GMT, Roland Karlsson
    <> wrote:

    >jpc wrote in news::
    >
    >> The pixels may be smaller, but two side by side pixels that vary by 5
    >> percent will still vary by 5 percent
    >>

    >
    >Yes - that sounds true - but whats your point?


    To quote "Smaller pixels will add to the noise
    and therefore decrease the ISO sensitivity. ----Or will it?--- If you
    have more pixels you don't have to enlarge the pixels so much."


    I was asking about/ commenting on the "Or will it?" I don't see how
    the amount of enlargement in a print would effect either the noise or
    the responsivity ( microvolts/photon) --aka the ISO sensitivity-- of a
    camera.

    jpc
    jpc, Aug 26, 2004
    #7
  8. "Don" <> wrote in message news:<q71Xc.179971$8_6.120005@attbi_s04>...
    > With the ever increasing Pixel count in Cameras, where is the turning point
    > where the top of the line Lenses would be no better than the pixel count.
    > From what I have seen allot of the newcomers to DSLRs are already not happy
    > about the soft focus on their lenses which shows that the pixel count is
    > much better than the Lens they are using.


    Just the opposite. Pin sharp film lenses are very, very blurry when
    used on all DLSRs, except one. Foveon offers the only acceptably
    sharp digital sensor. P&S's are worse.

    > It looks to me that 6 MP was great
    > for 90% of the users and now 8MP is good enough for about 98% of the users.
    > I still like it to be the Camera for the weak point of the max resoultion
    > as we can always change out the lens.
    Georgette Preddy, Aug 26, 2004
    #8
  9. Don

    Bruce Murphy Guest

    (Georgette Preddy) writes:

    > "Don" <> wrote in message news:<q71Xc.179971$8_6.120005@attbi_s04>...
    > > With the ever increasing Pixel count in Cameras, where is the turning point
    > > where the top of the line Lenses would be no better than the pixel count.
    > > From what I have seen allot of the newcomers to DSLRs are already not happy
    > > about the soft focus on their lenses which shows that the pixel count is
    > > much better than the Lens they are using.

    >
    > Just the opposite. Pin sharp film lenses are very, very blurry when
    > used on all DLSRs, except one. Foveon offers the only acceptably
    > sharp digital sensor. P&S's are worse.


    I didn't know sigma did astroturf.

    B>
    Bruce Murphy, Aug 26, 2004
    #9
  10. Don

    bob Guest

    "Martin Francis" <> wrote in
    news:cgiohj$g37$:

    >
    > Since when did anyone's photography demand the absolute highest
    > resolution of a lens?
    >


    It is really common for the lens to be the weakest link.

    Of the 20 or so Nikkor lenses I have owned over the years, there were only
    ever two (maybe three) that had enough resolution to really show the limits
    of my film. (24 2.8, 180 2.8, 60 micro).

    Bob

    --
    Delete the inverse SPAM to reply
    bob, Aug 26, 2004
    #10
  11. Don

    bob Guest

    "Drazen Stojcic / BUNTOVNIK" <> wrote in
    news:cgj51s$dr4$:

    > I'd say we're pretty safe in the lens resolution department up to 40
    > MP or so.
    >


    If you can make a large enough sensor (i.e. 8x10 inches), even that isn't
    enough, but at the 1/3" size the lenses seem to be pretty much pushed to
    their limits.

    Bob

    --
    Delete the inverse SPAM to reply
    bob, Aug 26, 2004
    #11
  12. Don

    Peter Irwin Guest

    Don <> wrote:

    > With the ever increasing Pixel count in Cameras, where is the turning
    > point where the top of the line Lenses would be no better than the
    > pixel count.


    I'm not an expert at this, but I'm going to try to answer anyway.
    Feel free to tear my analysis apart.

    There are some expensive long lenses with remarkable performance.
    The highest performance lens for 35mm which I know of is the
    Leica 280 f/4.0 Apo-Telyt-R. It is claimed to be diffraction limited
    at f/4. This means that its performance is practically identical to the
    theoretical maximum for a lens at f/4.0. This means that the limiting
    resolution should be about 400lp/mm and the usually more relevant
    50% MTF point should theoretically be around 200 lp/mm,
    but Leica claims only 150 lp/mm.

    The best lens that most of us are likely to own is a camera
    manufacturer's brand fast 50mm lens. It will have a limiting
    resolution close to the 1600/f-stop formula for f-stops of
    f/5.6 and smaller, but the 50% MTF figure is likely to be
    significantly worse than an ideal lens at middle f-stops.
    I understand that a 50% MTF in the 60 lp/mm range for the
    stops from f/5.6 to f/11 would be excellent performance.

    A digital sensor has a limiting resolution of one line pair for two
    pixels. This is called the Nyquist limit. The 50% MTF point can be
    estimated to be about 2/3 the Nyquist limit given a good anti-aliasing
    filter.

    Thus, if you wanted the 50% MTF resolution limit of a 24x36mm digital
    sensor to be the same as that of the Leica 280 f/4.0 Apo-Telyt-R,
    you would need 174 megapixels.

    If you wanted the 50% MTF resolution limit of a 24x36mm digital
    sensor to be the same as a good fast 50mm at middle stops you would
    need about 28 megapixels

    >From what I have seen allot of the newcomers to DSLRs are already
    > not happy about the soft focus on their lenses which shows that the
    > pixel count is much better than the Lens they are using.


    A Canon Digital Rebel (300d) has a sensor size of about 15x23mm
    and packs 6.3 megapixels into that small sensor. This would cause
    me to expect a 50% MTF resolution of about 45 lp/mm. I'm not sure
    how the kit zoom lens performs, but it is practically a sure thing
    that it won't be as good as a decent 50mm lens.

    It is also important to note that there is a significant benefit to
    making the lens better than the sensor (or film). If lens X has
    an MTF of 50% at 45 lp/mm and the sensor has an MTF of 50% at 45 lp/mm
    then the combined MTF at 45 lp/mm will only be 25%. If you then try a lens
    with an MTF of 65% at 45 lp/mm then the combined MTF at that
    spacial frequency will be up to 32.5%.

    Most inexpensive zoom lenses offer performance which is nowhere
    near that of good fixed focal length lenses or high quality zooms.
    This will be obvious whether you use film or digital.

    Peter.
    --


    >
    Peter Irwin, Aug 26, 2004
    #12
  13. Don

    bob Guest

    Peter Irwin <> wrote in news:cgjkle$6vf$:

    > A Canon Digital Rebel (300d) has a sensor size of about 15x23mm
    > and packs 6.3 megapixels into that small sensor. This would cause
    > me to expect a 50% MTF resolution of about 45 lp/mm. I'm not sure
    > how the kit zoom lens performs, but it is practically a sure thing
    > that it won't be as good as a decent 50mm lens.
    >


    I don't disagree with any of the other things you said in your post, but in
    addition, I would expect that manufacturing tolarances are measured in
    fixed terms (i.e, +/- .000x mm). Smaller lenses will by definition have
    greater variation (error).

    Bob


    --
    Delete the inverse SPAM to reply
    bob, Aug 26, 2004
    #13
  14. In article <q71Xc.179971$8_6.120005@attbi_s04>, "Don" <>
    wrote:

    > With the ever increasing Pixel count in Cameras, where is the turning point
    > where the top of the line Lenses would be no better than the pixel count.
    > From what I have seen allot of the newcomers to DSLRs are already not happy
    > about the soft focus on their lenses which shows that the pixel count is
    > much better than the Lens they are using. It looks to me that 6 MP was great
    > for 90% of the users and now 8MP is good enough for about 98% of the users.
    > I still like it to be the Camera for the weak point of the max resoultion
    > as we can always change out the lens.


    It's always a bit of a numbers game. With P&S cameras, the lens quality
    usually lags way behind the sensor resolution. A haze of a couple
    pixels across in the center and a total blur of a few pixels in the
    corners is typical. DSLR cameras can be upgraded to lenses beyond the
    sensor's quality.

    Sensor technology still has some room for improvement. Eventually it
    will be a matter of how much money you want to spend on the lens. I
    figure consumer cameras will stop around 16MP unless somebody invents a
    way to make cheaper lenses. The use of scan-backs and large format film
    proves that the desire for higher resolution professional sensors won't
    stop any time soon.
    Kevin McMurtrie, Aug 26, 2004
    #14
  15. In article <q71Xc.179971$8_6.120005@attbi_s04>, "Don" <>
    wrote:

    > With the ever increasing Pixel count in Cameras, where is the turning point
    > where the top of the line Lenses would be no better than the pixel count.
    > From what I have seen allot of the newcomers to DSLRs are already not happy
    > about the soft focus on their lenses which shows that the pixel count is
    > much better than the Lens they are using. It looks to me that 6 MP was great
    > for 90% of the users and now 8MP is good enough for about 98% of the users.
    > I still like it to be the Camera for the weak point of the max resoultion
    > as we can always change out the lens.


    It's always a bit of a numbers game. With P&S cameras, the lens quality
    usually lags way behind the sensor resolution. A haze of a couple
    pixels across in the center and a total blur of a few pixels in the
    corners is typical. DSLR cameras can be upgraded to lenses beyond the
    sensor's quality.

    Sensor technology still has some room for improvement. Eventually it
    will be a matter of how much money you want to spend on the lens. I
    figure consumer cameras will stop around 16MP unless somebody invents a
    way to make cheaper lenses. The use of scan-backs and large format film
    proves that the desire for higher resolution professional sensors won't
    stop any time soon.
    Kevin McMurtrie, Aug 26, 2004
    #15
  16. Don

    Mitch Alsup Guest

    Peter Irwin <> wrote in message news:<cgjkle$6vf$>...
    > Don <> wrote:

    <snip nice writeup>
    >
    > It is also important to note that there is a significant benefit to
    > making the lens better than the sensor (or film). If lens X has
    > an MTF of 50% at 45 lp/mm and the sensor has an MTF of 50% at 45 lp/mm
    > then the combined MTF at 45 lp/mm will only be 25%. If you then try a lens
    > with an MTF of 65% at 45 lp/mm then the combined MTF at that
    > spacial frequency will be up to 32.5%.


    It is also important to note that when the pixel size gets smaller
    than the smallest blur diameter (either lens aberations or difraction)
    that an antialiasing filter is no longer needed.
    Mitch Alsup, Aug 26, 2004
    #16
  17. "bob" <> wrote in message
    news:Xns9550ECDE8804Cbobatcarolnet@207.69.154.201...
    > "Martin Francis" <> wrote in
    > news:cgiohj$g37$:
    >
    > >
    > > Since when did anyone's photography demand the absolute highest
    > > resolution of a lens?
    > >

    >
    > It is really common for the lens to be the weakest link.


    Not even a tenth as common as for the photographer to be the weakest link.

    --
    Martin Francis http://www.sixbysix.co.uk
    "Go not to Usenet for counsel, for it will say both no, and yes, and
    no, and yes...."
    Martin Francis, Aug 26, 2004
    #17
  18. Don

    Guest

    "Don" <> wrote:

    > With the ever increasing Pixel count in Cameras, where is the turning point
    > where the top of the line Lenses would be no better than the pixel count.


    Pixel count is irrelevant.

    Diffraction limited optics have an angular resolution 1.22*l/D, l =
    wavelength, D = aperture (in the same units). Field of view of a
    pixel is u/f, u = pixel dimension, f = focal length (same units). The
    "turning point" is when you can get at least two pixels across the
    diffraction disk, or, after some re-arrangement, when the size of the
    pixel u ~ 0.61*l*n, where n = focal ratio of the optics.

    www.google.com: "diffraction limited optics"
    www.google.com: CCD "critical sampling"

    But if pixel count is all that excites you, you can take the above
    result, set l = 0.55, assume a 35mm format, and get P = 7700/n^2
    megapixels.
    , Aug 26, 2004
    #18
  19. jpc wrote in news::

    > I was asking about/ commenting on the "Or will it?" I don't see how
    > the amount of enlargement in a print would effect either the noise or
    > the responsivity ( microvolts/photon) --aka the ISO sensitivity-- of a
    > camera.
    >


    OK. Maybe you are right, but the useful sensitivity
    is affected by the number of pixels. The more pixels,
    the more pixels per area you get in the print. When you
    average over the pixels (either when printing or when
    looking at the print) you get more details in the dark
    areas.

    Therefor, it is not obvious that you lose sensitivity
    by having more pixels on the same area.

    Maybe ISO sensitivity does not take this into account,
    but it sure is a factor.


    /Roland
    Roland Karlsson, Aug 26, 2004
    #19
  20. Don

    Guest

    "Martin Francis" <> wrote:

    > Since when did anyone's photography demand the absolute highest resolution
    > of a lens?


    www.google.com: "hubble space telescope"

    ?
    , Aug 27, 2004
    #20
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