Ready to graduate to DSLR

Discussion in 'Digital Photography' started by Freedom55, Sep 17, 2005.

  1. It depends on the imaging specifications. The P&S cameras generally
    have lower resolution standards (angular resolution).
    Well, canon does have something like a 35 - 350 mm telephoto.
    Tamron has a 28-300 or something like that. Sigma has
    a 50 to 500 or something like that. How many such lenses
    do we need to say they are not rare. They perform OK, probably
    similar to the FZ20 lens in equivalent space. It is just they
    are not top performers. And that is exactly the point.
    The DSLR lets you choose the lenses you want: ultra zooms
    to fixed focal lengths, and you trade image quality in the decision
    (along with size, weight, cost, etc--but all with regard to
    image quality).

    Roger
     
    Roger N. Clark (change username to rnclark), Sep 22, 2005
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  2. Freedom55

    Stacey Guest

    Which lens? With the slow kit lens I agree.
     
    Stacey, Sep 22, 2005
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  3. Freedom55

    Stacey Guest

    That makes sense.. And I'd be willing to bet that it doesn't have the
    shutter responce that a normal 20D does..
     
    Stacey, Sep 22, 2005
  4. I don't see where you come up with this number. DOF is dependent on
    the final image size. If you assume 1 megapixel, you've thrown away
    a lot of image detail Did you do the same with the DSLR?
    How about defining a common print size, like 8x10 inches?
    Autofocus and multiple points were invented in film SLRs long before
    the digital cameras. It is a fraction of a second to move a focus point
    compared to the old manual way of moving the camera, manually focusing
    with the microprism and moving the camera back. A moving subject will
    have changed focus.

    Examples of moving animals; focus continually varying:
    Bird taking off: focus point set on bird's head and tracked:
    http://www.clarkvision.com/galleries/gallery.bird/web/egret.c03.01.2003.img_8764.b-600.html

    Bird landing focus continually changing, focus point on bird's head:
    http://www.clarkvision.com/galleries/gallery.bird/web/c12.17.2002.img_2501.crane.silho.c-600.html

    Bear fight: focus point on bear's eyes (vertical):
    http://www.clarkvision.com/galleries/gallery.bear/web/brown_bear.c09.09.2004.JZ3F4141.b-700.html
    moments later, switch to horizontal, move focus point and continue
    tracking action:
    http://www.clarkvision.com/galleries/gallery.bear/web/brown_bear.c09.09.2004.JZ3F4233.b-700.html

    Roger
     
    Roger N. Clark (change username to rnclark), Sep 22, 2005
  5. Freedom55

    Stacey Guest


    In case you need this explained, at least with CCD sensors, you MUST use an
    interline transfer CCD to have live preview or an electronic shutter. A
    full frame transfer CCD can NOT provide a live preview feed. For this
    reason the sensor used in the olympus dSLR's can't be used in a live
    preview camera. So yes these ARE dSLR sensors as the CAN NOT be used
    without an optical finder and a mechanical shutter

    I have no idea if the canon dSLR sensors work the same way and have the
    ability to work as an electronic shutter in software and provide a live
    preview either, do you?


    http://www.dpreview.com/reviews/kodakdcs620x/

    "Full Frame vs. Interline Transfer CCD's


    Interline Transfer CCD

    Your typical consumer digital camera uses what is called an Interline
    Transfer CCD, put simply the CCD can itself control the start / stop of
    when it measures light falling on it, otherwise known as an electronic
    shutter, it does so by shifting values out of the photodiodes into "shift
    registers" then pushing all of that data out as a final image. The
    advantages to Interline Transfer CCD's are simply that, they can be
    controlled by software and don't require a mechanical shutter (though are
    often used in conjunction with one) and can produce a video feed output (a
    requirement for a live preview LCD feed).


    Because of the extra electronics required around each pixel the "fill
    factor" (size of the photodiode) tends to be quite small (about 30% of the
    pixel area). To get around this Interline Transfer CCD manufacturers place
    a layer of "microlenses" (click here for electron microscope image of
    microlenses) over the CCD to capture more light and focus it onto the
    smaller photodiode area which then gives them an better effective fill
    factor of about 70%.



    Full Frame Transfer CCD




    Kodak's professional CCD's are Full Frame Transfer, they don't have a shift
    register, this means that a mechanical shutter is absolutely required to
    control the start / stop measurement of light. The shutter is opened and
    then closed again (say 1/60s later), the whole CCD shifts data off itself
    into the serial register where it's processed as the "RAW" image. As Full
    Frame CCD's are simpler (don't have shift registers and associated
    electronics around each photodiode) they have a much better Fill Factor
    (around 70%) and don't require or use microlenses.


    The disadvantage is that you can't get a video feed out of them which is the
    main reason we don't see more manufacturers using Full Frame CCD's (we're
    all too used to our LCD preview)."

    I can't see why canon or nikon etc would include all the extra parts to
    provide live preview and electronic shutter capabilities into a sensor
    (causing the photo sites to be smaller and make manufacturing more complex)
    when the sensor is never going to be used outside of a dSLR?
     
    Stacey, Sep 22, 2005
  6. Freedom55

    Stacey Guest

    Interesting the kodak full frame transfer sensors can't provide a live
    preview. So why do you believe all dSLR sensor would work when obviously
    some don't? Should you care about "getting things right" of course...
     
    Stacey, Sep 22, 2005
  7. Freedom55

    Stacey Guest

    Exactly. Or the "crackpots" that assume the main goal of EVERY photographer
    is to shoot at nightclubs handheld using avalible light and any camera that
    doesn't excell at this is useless for anyone to even consider....
     
    Stacey, Sep 22, 2005
  8. Freedom55

    Bryan Olson Guest

    Yes, of course, just as I wrote. I've lost track of what you are arguing.
    Not sure, but I think I see the problem. The point I was making about
    decoupling exposure at data-capture from exposure in the final image, and
    the point of the expose-to-the-right-technique, is not that one should
    never let a highlight blow out.

    In most cases, one wants the saturation point of the sensor to coincide
    with a low-point, a valley, a basin, of the image's histogram. Digital
    sensors (perhaps with rare exceptions) do not degrade gracefully at the
    high end. When transitions that should look smooth go from showing detail
    to blowing out, the change is often noticeable and, when it is noticeable,
    is almost always undesirable.

    So when, as usual, the saturation point falls in histogram valley, what
    is the effect of allowing more light -- moving the histogram to the
    right as far as is possible -- while keeping the saturation point in the
    trough? The positive effect is a better signal-to-noise ratio. Obviously
    there may be other ancillary effects from the change that admitted more
    light, be it shutter speed, aperture, or additional lighting, but those
    are not the issue here. There is no general negative effect of
    significance.

    "Expose to the right" is not exactly the same thing as "highlight-oriented
    exposing". Expose-to-the-right is not really about moving histograms to the
    left, though there are cases where the histogram can alert one to problems
    that should be solved by admitting less light. It is about capturing the
    most accurate and precise data possible, under the assumption that as long
    as the data is good, subsequent rendering can scale values as needed for a
    visually appealing result.
     
    Bryan Olson, Sep 22, 2005
  9. Freedom55

    Bryan Olson Guest

    Right. Did someone tell you that frame-transfer sensors are good for
    live preview? If so, I believe they steered you wrong.
    You lost me. I believe what I wrote, except in those cases where
    I have retracted. If there is something I wrote that is wrong and
    uncorrected, please let me know.

    I'll certainly do likewise. You were correct that most DSLR
    sensors do not have the ability to support live preview. What
    I disagreed with was what you reported gathering in:

    Yet it isn't using the same parts of the sensor to do this
    from what I've gathered?

    If you've found a good source on this, please let me know. I'm a bit
    behind the times in that I have not followed how CMOS sensors (with
    live preview) differ, on the logic level, from the workings of
    interline CCD's.
     
    Bryan Olson, Sep 22, 2005
  10. Freedom55

    Frank ess Guest

    Runaway favorite for Dead Horse Thread of the Year.
     
    Frank ess, Sep 22, 2005
  11. Freedom55

    ASAAR Guest

    Agreed. The reference was to one David J.

    Well, at least you're consistent. I can see the point you're
    trying to make but I still don't buy it. A complex DSLR (or P&S for
    that matter) can't be used effectively without a considerable amount
    of study, practice and 'smarts' (the kind in the cranium, not in the
    camera). The expert photographer may appear to be doing little
    thinking, but the truly skilled usually make what they're doing
    appear easy. But take that same "complex, no-think" camera away
    from the skilled amateur or pro and put it in the hands of a fairly
    smart novice, but one who has used the camera for a month or two and
    you'll see that the camera is not as "no-think" as it seemed. Put
    another way, a good mathematician may appear to be a wizard when
    his/her talents are seen by the public. But what they don't see are
    all of the mental shortcuts that were learned that greatly simplify
    what is being done. That doesn't mean the mathematician isn't
    thinking as much, even though results can be gotten with much less
    effort than you and I might require. You and I might technically be
    able to say that we're thinking more than the mathematician, but in
    the greater sense that would be either misleading or wrong. I
    think.

    Oh, sorry. You should have top posted this. We agreed to
    disagree, and so I continued doing just that! :)
     
    ASAAR, Sep 22, 2005
  12. I was wondering if it might be anything to do with designing specifically
    for a digital sensor - i.e. one where a higher MTF was wanted only up to a
    particular spatial frequency (half the sampling frequency), whereas a lens
    for a film camera might be designed to have a higher ultimate resolution
    (1% MTF or whatever)?

    You may not /need/ a top performer on a digital camera, as it can't use
    the highest spatial frequency content!

    David
     
    David J Taylor, Sep 22, 2005
  13. Freedom55

    Chris Brown Guest

    As descriptions go, that's kind of weak on detail.
    I reiterate, how do I know that I'm not blowing out the highlights that I
    care about? Specifically, with the example of eye-whites, they will be a
    tiny part of the image, and so lost in the noise (no pun intended) of the
    histogram. Sliding it to the right until you reach the next "lump" is quite
    likely to blow them.
    Occasionally you will get a scene where the light is very flat and it will
    give you a narrow histogram, with some freedom to shift it about without
    losing anything to over or under exposure. You don't particularly need the
    preview histogram to achieve this - a light meter and an understanding of
    what you're doing will do just fine. Probably the most useful thing a
    pre-exposure histogram could do in such a situation is inform you that this
    situation exists, if it wasn't already obvious. That's quite some way from
    the mighty metering tool it was originally portrayed as in this thread.
     
    Chris Brown, Sep 22, 2005
  14. Freedom55

    Chris Brown Guest

    OK, now think about what happens to the small areas of your interesting
    subject (e.g. eye-whites ina portrait) when you do this. The bulk of your
    subjetc is going to be to the left of your "valley", the blown highlights to
    the right. If your subject has small areas which are brighter than the rest
    of it (such as the eye-whites), the chances are they're going to be in this
    "valley", and you're either going to blow them, or move them into this area
    of graceless degredation of yours. You won't know you've done it either,
    because the histogram doesn't contain any spatial information. You know
    there are small bits of the image that fit in that "valley", but you don't
    know where they are, or if they're important. Small areas of wrongly-blown
    highlights can ruin an otherwise perfectly good shot.
    No, it's a subset of it.
     
    Chris Brown, Sep 22, 2005
  15. I think what is missing from this discussion is perspective and the
    bigger picture. Yes, a histogram alone doesn't tell you much.
    But combined with the LCD image where you see intensities (crudely),
    the histogram helps the photographer quantify the intensities
    seen in the image. Of course not always, but much of the time
    it does. If I am in a difficult situation, I zoom in on various
    parts of the scene, including the main subject, and take an
    image of that portion, noting the exposure time and intensities
    recorded (from BOTH the LCD and histogram). When used together
    the LCD image and histogram can tell you a lot about your exposure,
    but by themselves are too incomplete to be very useful.

    Roger
     
    Roger N. Clark (change username to rnclark), Sep 22, 2005
  16. "Roger N. Clark (change username to rnclark)" <>
    wrote in message SNIP
    Agreed, and if the display of 4 digit numbers is an objection (due to
    LCD clutter), then even a percentage of full well would be an
    improvement.

    Bart
     
    Bart van der Wolf, Sep 22, 2005
  17. Hard when one is at the long end of one's zoom, or is using a prime<g>.

    What you need is something like a "histogram dropper" that shows a small
    rectangle that can be scrolled around the image and displays the histogram
    for just what's in the rectangle (one would need better markings on the
    histogram than one usually gets).

    By the way, having ranted against Canon countless times for not giving us
    cheapskates a spot meter, I recently realized that the "fat spot" in both my
    Fuji GS645S and Mamiya 645 Pro (it claims to be a spot, but is almost as fat
    as the Fuji's spot) nails slide exposure 90% of the time.

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Sep 22, 2005
  18. Freedom55

    Bryan Olson Guest

    Chris Brown wrote:
    [...]
    A look at your image and the depth of the trough.

    [...]
    And occasionally you'll get a scene where the expose-to-the
    right technique will not apply. Learn something or don't,
    your choice.
     
    Bryan Olson, Sep 22, 2005
  19. Expose to the right doesn't apply to (among others) every scene that you
    might want to let some of the highlights blow. Every night scene, every
    bright cloud scene, every backlit scene.

    That's a lot of scenes. (Seriously, it seems that the cases where it doesn't
    apply is exactly the set of cases where coming up with a good exposure is
    hard.)

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, Sep 22, 2005
  20. Freedom55

    Chris Brown Guest

    If the highlights in my subject are small, their contribution to the
    histogram will be negligible, but blowing them will still ruin my image, so
    this doesn't help at all.
    Eureka, I think we're getting somewhere!
     
    Chris Brown, Sep 22, 2005
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