Re: Backlit sensors

Discussion in 'Digital Photography' started by Chrlz, Mar 6, 2010.

  1. Chrlz

    Chrlz Guest

    On Mar 6, 6:07 pm, Alfred Molon <> wrote:
    > A few compact cameras with backlit sensors have been launched. Are there
    > any reviews or comparisons detailing how the performance is compared to
    > standard cameras?
    > --
    >
    > Alfred Molon


    I think the Nikon P100 is the only back-illuminated sensor camera out
    so far. The few reviews I've seen are not in depth, but they didn't
    seem overly impressed with the image quality/high ISO performance.
    (Having said that, Nikon's (non-dslr) design team doesn't exactly
    shine when it comes to wringing performance out of their pretty
    mediocre bridge and p&s cameras...)

    Fuji's upcoming HS10 has pretty wild specifications on paper. Fuji
    has been known to get a couple of their little cameras to perform well
    in the high ISO area, so that one might be more interesting. However,
    pushing a superzoom that far (24-720?...!!!) has gotta be asking for
    trouble, even if the sensor is good. There's some optical science
    standing in the way of such feats...

    As always, I think the hype will exceed the reality significantly -
    but any improvement in photon-efficiency is a step in the right
    direction.
    Chrlz, Mar 6, 2010
    #1
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  2. Chrlz

    Paul Furman Guest

    Chrlz wrote:
    > Alfred Molon wrote:
    >> A few compact cameras with backlit sensors have been launched. Are there
    >> any reviews or comparisons detailing how the performance is compared to
    >> standard cameras?

    >
    > I think the Nikon P100 is the only back-illuminated sensor camera out
    > so far. The few reviews I've seen are not in depth, but they didn't
    > seem overly impressed with the image quality/high ISO performance.


    I suspect part of the reason for putting the wiring on the back is to be
    able to get full 1080 HD video out at 30fps. Sony has done this for some
    video cameras, claiming double the sensitivity but remember doubling is
    just one stop.
    http://www.dpreview.com/news/0908/09080601sonycmos.asp
    "However, compared to conventional front-illuminated structures,
    back-illuminated structures commonly causes problems such as noise, dark
    current, defective pixels and color mixture that lead to image
    degradation and also cause a decrease in the signal-to-noise ratio."

    > (Having said that, Nikon's (non-dslr) design team doesn't exactly
    > shine when it comes to wringing performance out of their pretty
    > mediocre bridge and p&s cameras...)
    >
    > Fuji's upcoming HS10 has pretty wild specifications on paper. Fuji
    > has been known to get a couple of their little cameras to perform well
    > in the high ISO area, so that one might be more interesting. However,
    > pushing a superzoom that far (24-720?...!!!) has gotta be asking for
    > trouble, even if the sensor is good. There's some optical science
    > standing in the way of such feats...
    >
    > As always, I think the hype will exceed the reality significantly -
    > but any improvement in photon-efficiency is a step in the right
    > direction.
    Paul Furman, Mar 6, 2010
    #2
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  3. "Alfred Molon" <> wrote in message
    news:...
    > In article <hmucu8$eke$-september.org>, paul-@-
    > edgehill.net says...
    >> http://www.dpreview.com/news/0908/09080601sonycmos.asp
    >> "However, compared to conventional front-illuminated structures,
    >> back-illuminated structures commonly causes problems such as noise,
    >> dark
    >> current, defective pixels and color mixture that lead to image
    >> degradation and also cause a decrease in the signal-to-noise ratio."

    >
    > Strange. The ability to capture more light should lead to less noise,
    > not more.


    Yes. more light, but other problems caused by back-illumination, so
    there's a trade-off point where the problems caused by back-lighting are
    less than than the gains, and when that's reached, backlit sensors become
    a better choice. I think we saw something similar as CCD has been
    gradually replaced by CMOS.

    Cheers,
    David
    David J Taylor, Mar 7, 2010
    #3
  4. "Alfred Molon" <> wrote in message
    news:...
    > In article <hn013e$1f7$-september.org>, david-
    > lid says...
    >
    >> Yes. more light, but other problems caused by back-illumination, so
    >> there's a trade-off point where the problems caused by back-lighting
    >> are
    >> less than than the gains, and when that's reached, backlit sensors
    >> become
    >> a better choice.

    >
    > What other problems are you referring to?
    > --
    >
    > Alfred Molon


    The ones you originally referred to in:

    http://www.dpreview.com/news/0908/09080601sonycmos.asp

    David
    David J Taylor, Mar 7, 2010
    #4
  5. Chrlz

    Paul Furman Guest

    Alfred Molon wrote:
    > In article<hn013e$1f7$-september.org>, david-
    > lid says...
    >
    >> Yes. more light, but other problems caused by back-illumination, so
    >> there's a trade-off point where the problems caused by back-lighting are
    >> less than than the gains, and when that's reached, backlit sensors become
    >> a better choice.

    >
    > What other problems are you referring to?


    It was in the link and quote.

    http://www.dpreview.com/news/0908/09080601sonycmos.asp
    "...back-illuminated structures commonly causes problems such as noise,
    dark current, defective pixels and color mixture that lead to image
    degradation and also cause a decrease in the signal-to-noise ratio."

    CCD used to be considered better than CMOS but technology advances, CMOS
    has more room for circuitry so advanced things can be done to improve
    performance, probably similar to the back illumination issue. I believe
    the very high end scientific sensors are still CCD though. Meh, I should
    shut up, I only have the vaguest idea <g> but have seen these issues
    discussed...
    Paul Furman, Mar 7, 2010
    #5
  6. "Pete D" <> wrote in message
    news:...
    []
    > Surprisingling though some the best low noise cameras at the moment are
    > still CCD.
    >
    > I think we saw something similar as CCD has been
    >> gradually replaced by CMOS.
    >>
    >> Cheers,
    >> David


    Well, not that surprising as the point where CMOS become better will
    depend on so many factors that the point in time will be different for
    various processes, and from what factors the designers consider important.

    Cheers,
    David
    David J Taylor, Mar 8, 2010
    #6
  7. "Alfred Molon" <> wrote in message
    news:...
    > In article <hn12c5$t1f$-september.org>, david-
    > lid says...
    >>
    >> The ones you originally referred to in:
    >>
    >> http://www.dpreview.com/news/0908/09080601sonycmos.asp

    >
    > I didn't refer to any problems, but it looks that you don't know what
    > you are talking about.
    > --
    >
    > Alfred Molon



    You posted:

    _________________________________________________
    In article <hmucu8$eke$-september.org>, paul-@-
    edgehill.net says...
    > http://www.dpreview.com/news/0908/09080601sonycmos.asp
    > "However, compared to conventional front-illuminated structures,
    > back-illuminated structures commonly causes problems such as noise, dark
    > current, defective pixels and color mixture that lead to image
    > degradation and also cause a decrease in the signal-to-noise ratio."


    Strange. The ability to capture more light should lead to less noise,
    not more.
    _________________________________________________


    Your "strange" suggested to me that you had not appreciated the problems
    to which DP Review referred.

    Why the personal insult?

    David
    David J Taylor, Mar 8, 2010
    #7
  8. Chrlz

    Bruce Guest

    On Mon, 8 Mar 2010 07:55:03 -0000, "David J Taylor"
    <> wrote:

    >"Alfred Molon" <> wrote in message
    >news:...
    >> In article <hn12c5$t1f$-september.org>, david-
    >> lid says...
    >>>
    >>> The ones you originally referred to in:
    >>>
    >>> http://www.dpreview.com/news/0908/09080601sonycmos.asp

    >>
    >> I didn't refer to any problems, but it looks that you don't know what
    >> you are talking about.
    >> --
    >>
    >> Alfred Molon

    >
    >
    >You posted:
    >
    >_________________________________________________
    >In article <hmucu8$eke$-september.org>, paul-@-
    >edgehill.net says...
    >> http://www.dpreview.com/news/0908/09080601sonycmos.asp
    >> "However, compared to conventional front-illuminated structures,
    >> back-illuminated structures commonly causes problems such as noise, dark
    >> current, defective pixels and color mixture that lead to image
    >> degradation and also cause a decrease in the signal-to-noise ratio."

    >
    >Strange. The ability to capture more light should lead to less noise,
    >not more.
    >_________________________________________________
    >
    >
    >Your "strange" suggested to me that you had not appreciated the problems
    >to which DP Review referred.
    >
    >Why the personal insult?



    You seem very over-sensitive to having your ideas criticised. Do you
    take every little disagreement personally? If so, why?

    This is Usenet. Get used to it. And stop throwing your toys out of
    the pram every time someone disagrees with you. It is your ideas that
    they are disagreeing with.
    Bruce, Mar 8, 2010
    #8
  9. "Bruce" <> wrote in message
    news:...
    []
    > You seem very over-sensitive to having your ideas criticised. Do you
    > take every little disagreement personally? If so, why?
    >
    > This is Usenet. Get used to it. And stop throwing your toys out of
    > the pram every time someone disagrees with you. It is your ideas that
    > they are disagreeing with.


    Bruce,

    I felt that Alfred's comment: "it looks that you don't know what you are
    talking about." was uncalled for, and he offered no justification. It's
    not the same as saying: "I don't agree with you" or "you misunderstood
    what I wrote".

    For example, I know that we don't agree on choice of equipment, but that's
    because we have different aims and objectives. I don't say that "you
    don't know what you are talking about" just because you have different
    ideas.

    I don't take insults in my personal life, so I see no reason to do so
    here, and I use my kill-file accordingly. Banter between friends in one
    thing, a public accusation of incompetence is something else.

    Cheers,
    David
    David J Taylor, Mar 8, 2010
    #9
  10. David J Taylor wrote:
    >
    > "Bruce" <> wrote in message
    > news:...
    > []
    >> You seem very over-sensitive to having your ideas criticised. Do you
    >> take every little disagreement personally? If so, why?
    >>
    >> This is Usenet. Get used to it. And stop throwing your toys out of
    >> the pram every time someone disagrees with you. It is your ideas that
    >> they are disagreeing with.

    >
    > Bruce,
    >
    > I felt that Alfred's comment: "it looks that you don't know what you are
    > talking about." was uncalled for, and he offered no justification. It's
    > not the same as saying: "I don't agree with you" or "you misunderstood
    > what I wrote".
    >
    > For example, I know that we don't agree on choice of equipment, but
    > that's because we have different aims and objectives. I don't say that
    > "you don't know what you are talking about" just because you have
    > different ideas.
    >
    > I don't take insults in my personal life, so I see no reason to do so
    > here, and I use my kill-file accordingly. Banter between friends in one
    > thing, a public accusation of incompetence is something else.



    Well said.

    --
    john mcwilliams

    Remember: Opinions are like buttocks; only those which are well-formed
    should be shown in public.
    John McWilliams, Mar 8, 2010
    #10
  11. "Alfred Molon" <> wrote in message
    news:...
    []
    > It was Paul who mentioned those problems, not me.


    Indeed, but it was you who asked what the problems were.

    >> Your "strange" suggested to me that you had not appreciated the
    >> problems
    >> to which DP Review referred.
    >>
    >> Why the personal insult?

    >
    > "you don't know what you are talking about" is not an insult.


    I consider it to be so, when it is not backed up by reasoned and cited
    refutation of what I said. But if I get something wrong, I do appreciate
    it being pointed out so that I can learn for the next time.

    > Besides, somebody who repeats what he has read somewhere without having
    > understood this and being able to explain this, does not know what he is
    > talking about.
    > --
    >
    > Alfred Molon


    That's not necessarily true if an adequate explanation has already been
    given - unless phrasing something in a different way helps understanding.
    I saw no need to give further explanation in this case.

    If you would like something explained further you only need to ask
    politely. If I can explain, I will, if not, I will say that I don't know.

    Cheers,
    David
    David J Taylor, Mar 8, 2010
    #11
  12. Alfred Molon wrote:
    > In article <hn2ago$rir$-september.org>, david-
    > lid says...


    >> Why the personal insult?

    >
    > "you don't know what you are talking about" is not an insult.


    You don't know what you are talking about, Alfred.

    --
    john mcwilliams
    John McWilliams, Mar 9, 2010
    #12
  13. Chrlz

    Martin Brown Guest

    Alfred Molon wrote:
    > In article <hn013e$1f7$-september.org>, david-
    > lid says...
    >
    >> Yes. more light, but other problems caused by back-illumination, so
    >> there's a trade-off point where the problems caused by back-lighting are
    >> less than than the gains, and when that's reached, backlit sensors become
    >> a better choice.

    >
    > What other problems are you referring to?


    The main one for single shot colour is that for a front illuminated
    Bayer mask CCD the electronics structures help to prevent cross talk
    between adjacent pixels. When the CCD is back illuminated there is
    nothing in the way of stray photons at oblique angles. This gets
    trickier at short focal lengths with fast lenses.

    It doesn't matter so much for monochromatic scientific imaging systems
    as they are almost always oversampled anyway. But it does matter a lot
    when the adjacent channel is through a different colour filter.

    The astonishing thing remains that they can do this at all at a price
    and quality where consumer grade equipment can be made with them.

    Regards,
    Martin Brown
    Martin Brown, Mar 9, 2010
    #13
  14. Chrlz

    Martin Brown Guest

    Alfred Molon wrote:
    > In article <KNoln.36306$>,
    > |||newspam|||@nezumi.demon.co.uk says...
    >
    >> The main one for single shot colour is that for a front illuminated
    >> Bayer mask CCD the electronics structures help to prevent cross talk
    >> between adjacent pixels. When the CCD is back illuminated there is
    >> nothing in the way of stray photons at oblique angles. This gets
    >> trickier at short focal lengths with fast lenses.

    >
    > I would have assumed that this is a non-issue, since the colour filters
    > are directly on the imager, not far away from it. In any case, do you
    > have any references for this for further reading?


    You will have to look in the patent literature for details.

    I don't think there are any articles at all about the backlit Sony
    design apart from the ones already discussed.

    There is a nice article about colour imaging which doesn't get that far
    but otherwise has a lot of other good stuff.

    http://www.technologysupplies.co.uk/rapmankit.htm
    http://white.stanford.edu/~brian/psy221/reader/Wandell.Color Reproduction.pdf


    (and references therein)

    Regards,
    Martin Brown
    Martin Brown, Mar 10, 2010
    #14
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