Optical Zoom versus Cropping on PC

Discussion in 'Digital Photography' started by crypkema@gmail.com, Dec 21, 2006.

  1. Guest

    Here's a thought I had and I wonder if any of you have experience in
    this. Can you get the same effect with cropping a picture on your PC
    as you can with a large optical zoom on 6-8 megapixel cameras, assuming
    your intent is to have 4x6 or 5x8 snapshots?

    My first digital camera was an Olympus C750, a 2 megapixel camera with
    a 10x optical zoom. At only 2 megapixels, you wanted to do your
    framing when you took the shot, not on the PC because when you blew it
    up, it would look grainy.

    With the advent of 6-8 megapixel cameras, it seems you could get by
    with a 3x optical zoom and then crop the picture on a PC before
    printing. With the additional data, you should still be able to get
    good snapshots.

    So does my theory hold water, or am I looking at things wrong?

    Thank you, and Merry Christmas!
    Chris
    , Dec 21, 2006
    #1
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  2. jeremy Guest

    <> wrote in message
    news:...
    > Here's a thought I had and I wonder if any of you have experience in
    > this. Can you get the same effect with cropping a picture on your PC
    > as you can with a large optical zoom on 6-8 megapixel cameras, assuming
    > your intent is to have 4x6 or 5x8 snapshots?
    >
    > My first digital camera was an Olympus C750, a 2 megapixel camera with
    > a 10x optical zoom. At only 2 megapixels, you wanted to do your
    > framing when you took the shot, not on the PC because when you blew it
    > up, it would look grainy.
    >
    > With the advent of 6-8 megapixel cameras, it seems you could get by
    > with a 3x optical zoom and then crop the picture on a PC before
    > printing. With the additional data, you should still be able to get
    > good snapshots.
    >
    > So does my theory hold water, or am I looking at things wrong?
    >
    > Thank you, and Merry Christmas!
    > Chris
    >


    Well, sort of, but not exactly. If you zoom in optically, the enlarged
    image is recorded using all the resolution that your camera has.

    If you zoom out, and then crop the photo to simulate zoom, you have thrown
    away pixels, and the remaining image will be spread over fewer remaining
    pixels.

    The degree of image degradation would depend on such factors as the
    percentage of the photo that you "threw away" by cropping, and how many
    megapixels your camera had to begin with. Theoretically, the cropped image
    should look worse.

    It is always better to use optical zoom, rather than cropping away the
    unwanted edges of the image.
    jeremy, Dec 21, 2006
    #2
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  3. Scott W Guest

    wrote:
    > Here's a thought I had and I wonder if any of you have experience in
    > this. Can you get the same effect with cropping a picture on your PC
    > as you can with a large optical zoom on 6-8 megapixel cameras, assuming
    > your intent is to have 4x6 or 5x8 snapshots?
    >
    > My first digital camera was an Olympus C750, a 2 megapixel camera with
    > a 10x optical zoom. At only 2 megapixels, you wanted to do your
    > framing when you took the shot, not on the PC because when you blew it
    > up, it would look grainy.
    >
    > With the advent of 6-8 megapixel cameras, it seems you could get by
    > with a 3x optical zoom and then crop the picture on a PC before
    > printing. With the additional data, you should still be able to get
    > good snapshots.
    >
    > So does my theory hold water, or am I looking at things wrong?
    >


    This really does not work all that well. Let's say you are going to be
    printing 4 x 6 prints at 300 ppi, you are then looking at wanting just
    over 2MP for your print, if you start out with 8MP this give you a
    factor of close to two. So a 8MP with a 3X optical zoom would be close
    to a 2MP with a 6X optical zoom, so you are not even close to the 10x
    optical zoom on your old 2MP camera. What is more it is likely that
    your old camera had sharper pixels then many of the current compact 8MP
    cameras.

    Scott
    Scott W, Dec 21, 2006
    #3
  4. ASAAR Guest

    On 20 Dec 2006 20:10:47 -0800, wrote:

    > Here's a thought I had and I wonder if any of you have experience in
    > this. Can you get the same effect with cropping a picture on your PC
    > as you can with a large optical zoom on 6-8 megapixel cameras, assuming
    > your intent is to have 4x6 or 5x8 snapshots?
    >
    > My first digital camera was an Olympus C750, a 2 megapixel camera with
    > a 10x optical zoom. At only 2 megapixels, you wanted to do your
    > framing when you took the shot, not on the PC because when you blew it
    > up, it would look grainy.
    >
    > With the advent of 6-8 megapixel cameras, it seems you could get by
    > with a 3x optical zoom and then crop the picture on a PC before
    > printing. With the additional data, you should still be able to get
    > good snapshots.
    >
    > So does my theory hold water, or am I looking at things wrong?


    It depends on what you find acceptable and how much you intend to
    crop. Assuming that all pixels are the same (but they aren't,
    really) if you crop the image from a 6-8mp camera so that only 2mp
    remain, you'd be able to produce 4"x6" and 5"x8" (5x7?) snapshots
    roughly comparable to what your C750 produced. The 4"x6" prints
    would probably look very good, but the 5"x8" prints wouldn't hold up
    as well. But if your cropping was less drastic, throwing away only
    1/2 of all the pixels, the resulting 3mp or 4mp image should easily
    produce better prints than your C750 did.

    Additionally, different people have different requirements. I can
    do quite a bit of cropping of my camera's 4mp images and still
    produce excellent 4"x6" snapshots. But if you're familiar with the
    term "circle of confusion" you'll realize that acceptability depends
    on the viewer's vision, how close the print is that they're
    examining, whether the prints need to meet publication requirements,
    whether the prints are portraits (which can tolerate more softness),
    etc. You could probably make very nice cropped 5" x 8" prints from
    6-8mp cameras, that a few of our resident pixel peepers would get so
    close to that they'd get nose grease stains on the print before
    calling the prints "hideous". Don't believe it.

    What you can do even before getting a higher resolution camera is
    to download some of the full resolution test shots from one or more
    of the camera review websites made by one or more of the 6-8mp
    cameras you're considering (well, maybe you aren't considering
    getting one - you did say that you were examining a theory),
    cropping them and making a few 4"x6" and 5"x8" prints. Judge for
    yourself whether the prints are great, decent or horrible. Get
    opinions from friends and relatives, since your eyesight may be not
    be as good as, or may be better than theirs.
    ASAAR, Dec 21, 2006
    #4
  5. Guest

    Thank you everyone for the opinions. You've given me some food for
    thought.

    My question was more than just theory. My daughter had her purse
    stolen and in the purse was her Olympus C755. We'll need to replace it
    and so I've been debating between one of the smaller ultrazoom cameras
    like the Olympus C755, the Olympus SP-510UZ, and the larger Canon
    S2/S3.

    As I've been looking through the ads, (this is a great time to shop for
    cameras), I noticed cameras like the Canon PowerShot G7 with a 6x
    optical zoom, image stabilization (like the S2/S3) and 10 megapixels.
    It seemed like an alternative to the 12x zoom in the S2/S3.

    Merry Christmas to you all. I'll check back in case anyone else has
    some thoughts on this idea.

    Chris
    , Dec 21, 2006
    #5
  6. timeOday Guest

    Scott W wrote:
    > wrote:
    >
    >>Here's a thought I had and I wonder if any of you have experience in
    >>this. Can you get the same effect with cropping a picture on your PC
    >>as you can with a large optical zoom on 6-8 megapixel cameras, assuming
    >>your intent is to have 4x6 or 5x8 snapshots?
    >>
    >>My first digital camera was an Olympus C750, a 2 megapixel camera with
    >>a 10x optical zoom. At only 2 megapixels, you wanted to do your
    >>framing when you took the shot, not on the PC because when you blew it
    >>up, it would look grainy.
    >>
    >>With the advent of 6-8 megapixel cameras, it seems you could get by
    >>with a 3x optical zoom and then crop the picture on a PC before
    >>printing. With the additional data, you should still be able to get
    >>good snapshots.
    >>
    >>So does my theory hold water, or am I looking at things wrong?
    >>

    >
    >
    > This really does not work all that well. Let's say you are going to be
    > printing 4 x 6 prints at 300 ppi, you are then looking at wanting just
    > over 2MP for your print, if you start out with 8MP this give you a
    > factor of close to two. So a 8MP with a 3X optical zoom would be close
    > to a 2MP with a 6X optical zoom, so you are not even close to the 10x
    > optical zoom on your old 2MP camera. What is more it is likely that
    > your old camera had sharper pixels then many of the current compact 8MP
    > cameras.
    >
    > Scott
    >


    Good analysis, except I think there's an unstated assumption that the
    2mp and 8mp cameras have the same minimum focal length, since "zoom" is
    simply a ratio of maximum/minimum focal length. It might make sense to
    talk about the ratio of the two cameras' maximum focal lengths (in 35mm
    equiv).

    One factor in favor of digital cropping is that you don't have to frame
    the shot correctly in the first place. That's a huge advantage for
    action shots. I also find it handy when taking pictures of people,
    especially kids - I like to look at them directly instead of through the
    viewfinder, it makes it easier to time the shot and I can engage them
    better, but it decreases framing accuracy. Even with nature shots, I
    sometimes find one portion of the image comes out unexpectedly
    interesting (or rather the rest unexpectedly boring) so being able to
    crop is nice.

    Anyways, I don't personally find long focal lengths terribly useful
    without a reasonably large aperture, which a compact camera cannot have
    by definition. So you can zoom in to get a picture of your kid
    accepting his diploma, but you get a dark, grainy, blurred image.
    timeOday, Dec 22, 2006
    #6
  7. John Turco Guest

    wrote:
    >
    > Thank you everyone for the opinions. You've given me some food for
    > thought.
    >
    > My question was more than just theory. My daughter had her purse
    > stolen and in the purse was her Olympus C755. We'll need to replace it
    > and so I've been debating between one of the smaller ultrazoom cameras
    > like the Olympus C755, the Olympus SP-510UZ, and the larger Canon
    > S2/S3.
    >
    > As I've been looking through the ads, (this is a great time to shop for
    > cameras), I noticed cameras like the Canon PowerShot G7 with a 6x
    > optical zoom, image stabilization (like the S2/S3) and 10 megapixels.
    > It seemed like an alternative to the 12x zoom in the S2/S3.
    >
    > Merry Christmas to you all. I'll check back in case anyone else has
    > some thoughts on this idea.
    >
    > Chris



    Hello, Chris:

    If price is of particular concern, you should consider the Kodak
    P850. I have one, and am quite delighted with its 5MP resolution,
    12x zoom, optical image stabilization and plethora of automatic
    and manual functions, all coming at a surprisingly low cost.

    Then, if your kid's P850 falls victim to another purse-snatching
    incident, you won't be out a lot of money. (Relatively speaking,
    naturally. <g>)

    Good luck, and happy holidays!


    Cordially,
    John Turco <>
    John Turco, Dec 23, 2006
    #7
  8. Guest

    I ended up choosing the Canon A630 for her. In the end, I was
    pleasantly surprised at what Canon has managed to accomplish.

    Basically, they have taken the idea I had in the beginning, and made it
    almost effortless to accomplish on a digital camera.

    The A630 has a 4x optical zoom and a 4x digital zoom (8 mp). As you
    zoom in on a scene, the camera stops at the limit of what will be a
    clear shot. At that point, you can either
    1. stop and leave the zoom where it is
    2. continue zooming in and risk a degraded picture
    3. reduce the picture size (pixels) and zoom in further with what is
    termed a safe zoom.

    I spent several hours taking comparison pictures between the A710 (6x
    optical zoom with image stabilization), the A630 (4x optical zoom and
    no IS) and my S2 with 12x optical zoom and IS. Some of the shots were
    taken in my downstairs at night with poor lighting and across the room.
    By cutting the image size down on both, I could get to a 9-10x zoom
    factor and still get very good detail. The noise level was not
    noticeable till I magnified the images considerably. And while my S2
    did slightly better, the differences between the images was hard to see
    with my unprofessional eyes.

    I also took some pictures of a wine glass with the A710 and A630. The
    detail level was enough that you could see the dust on the edge of the
    glass, and this was with the digital zoom enabled.

    So while there is a compromise in that the image size is smaller than
    what the camera is capable of doing, it isn't that bad. And
    considering the image size was about what a 4 mp camera would
    produce...which is acceptable for most snapshots, I think it'll work
    for her.

    Chris
    , Dec 27, 2006
    #8
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