Comparison of dSLR to SLR

Discussion in 'Digital SLR' started by Rob, Feb 15, 2006.

  1. Rob

    Rob Guest

    I was watching Modern Marvels last nite and they had a show on the
    digital age. In it they mentioned that todays 6 to 7 megapixel
    digital cameras are the equivalent to the older SLR film cameras.

    I don't know how to do the math to compare but about 3 years ago I saw
    someone try and I thought the concensus of opinion around here was
    like 9 to 11 megapixels.

    Two questions come to mind tho the first one is probably above my
    head. How do you calculate to compare? And what is the right
    megapixel number to be equivalent to the SLR film cameras? Is it
    really a judgement call or is there a way to calculate a definitive
    number for the comparison?

    Rob, Feb 15, 2006
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  2. Rob

    Scott W Guest

    A lot depends on the film used there is a pretty large range just based
    on this.
    But even beyond that the two media are a fair bit different, with film
    having good resolution when imaging very high contrast targets but film
    also has a lot of noise with makes it look soft.

    There is no consensus on as to how many MP you need to match any given
    film and there is a lot of BS floating around. This ends up being a
    pretty subjective call and for my own part the best film scan that I
    have every seen was a pretty good match to the 8MP I get out of the
    20D. Others believe a film like Velvia matches a digital camera in
    the 12 MP range or so.

    Beyond the film that is used there is also the question of how the film
    is scanned. It takes a very good film scanner to get into the range of
    8MP out of even a good pro film.

    Scott W, Feb 15, 2006
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  3. Hi Rob
    I haven't seen anyone come up with the math that shows why I'm
    happier with my Nikon D70 (6 MP) images than my Nikon F5/Fuji-low-ISO
    film images. Even more so with Nikon D200 (10MP) images. Even
    more so at higher ISO points.

    A few years back I thought we'd need to get to 20MP or so. Silly me.

    Bottom line: modern dSLRs beat film.

    -- stan
    Stanley Krute, Feb 15, 2006
  4. Rob

    Jeremy Nixon Guest

    The problem with even trying to do this is that "megapixels" is not a
    "quality index", despite what the marketing crap tries to lead you to
    believe. There simply is not, and cannot be, some magic number of
    megapixels that will equal the quality of some arbitrary film, especially
    when it's perfectly reasonable for a digital camera with a higher number
    of "megapixels" to be of lower quality than one with fewer.
    Jeremy Nixon, Feb 15, 2006
  5. Rob

    wilt Guest

    Very subjective, what you think could be objectively evaluated!

    At first blush, you'd think you could look at spatial resolution of
    film vs. digital pixels, but then you have to say 'which film?' to
    compare against. So then, since lenses are often the limitation to
    spatial resolution, you pick a good lens and say "make digital resolve
    to that level", but then you ignore the important point that film
    performance is not merely spatial is also the tonality
    that is captured, where lens resolution itself is not the limiting
    factor. The, as some have pointed out, there is a tendency to compare
    'digitally scanned film' vs. 'native digital' and you're leaving
    performane on the table by introducing one more generation of
    reproduction via the scanner! And not everyone WANTS a digital
    file...a big enlargement on a billboard or on a institutional wall
    might be the end product which is desired. And then there is the issue
    that, with noise removal and other techniques, the native digital file
    tends to be 'improved' whereas a film image does not have benefit of
    the same 'improvement'. And lastly, you can get a 'smoothness' in a
    digital image which is compared to the inherent graininess or color
    cloud clumping that results in film and photographic paper print!
    wilt, Feb 15, 2006
  6. Rob

    wilt Guest

    Just adding my own subjective experience, to the disclaimer of
    objective comparison...

    I had 4MP point and shoot to replace my film P&S. It was good enough
    for that. But...
    I had been using 35mm film SLR for nearly 40 years, but no *affordable*
    dSLR could provide me with the same quality of photos as 35mm film,
    until the past year. I finally bought 8MP dSLR (for about the same
    amount of money as a medium format film SLR body+film magazine+metering
    prism). At 8MP, it finally had crossed the threshold of acceptability
    for me vs. 35mm film SLR...and I have shot both MF film and LF film
    cameras professionally to more strongly bias my eye in the direction of
    image quality than most amateurs/enthusiasts.
    wilt, Feb 15, 2006
  7. Rob

    Bill Funk Guest

    Trying to peg an equivalency between film and digital to only MPs is
    like trying to compare a Chevy to a Ferrari by engine size.
    Bill Funk, Feb 15, 2006
  8. For most applications that 35mm is suitable for in the first place. I
    generally agree.

    I don't have "the math" for this; I don't think we have a good enough
    numeric index of "quality" to settle this issue with math anyway,

    I do think I have a rough understanding of what's going on, though.

    It's simple: 35mm film is largely limited by artifacts (grain) which
    are made more visible by enlargement. This sets the useful limit on
    enlargement of 35mm film -- sets it rather low.

    Digital images have less digital noise than film has grain, and the
    ratio gets more in favor of digital as the ISO increases.

    And finally, the human eye mostly *doesn't notice missing detail*.
    The sorts of photos where even the human eye will notice missing
    detail tend to be shot, by professionals, with medium format or large
    format cameras. (razor-sharp silhouettes of complex clusters of tree
    branches against the sky and suchlike).

    The end result is that photos shot by pros on 35mm tend to look better
    in digital than on film.

    People, mostly amateurs, trying to do work that really wants MF in
    35mm, often complain about the lack of resolution in digital. People
    not doing that kind of work think they're crazy or overly
    anal-retentive, but they're not, they're just used to extracting stuff
    from 35mm that's barely there in film.

    To put it differently, digital images over-enlarge (those of us who've
    done a lot of darkroom work all know roughly what we mean by
    "over-enlarge", right?) considerably better than film images. And
    35mm film images are nearly always over-enlarged.
    David Dyer-Bennet, Feb 15, 2006
  9. I don't think it is so much of grain issue (except for people who can't stand
    grain) but it is much more a resolution problem.

    Digital cameras have much better MTF graphs than film. Yes, film can handle
    much higher resolutions for high contrast details, but for subjects with
    normal contrast, there is soon not enough contrast left.

    Of course, with scanners and digital prints, sharpening can make larger
    prints posible than with traditional enlargers.
    Philip Homburg, Feb 15, 2006
  10. Rob

    Skip M Guest

    One problem with comparing digital to film is, "Which film?" Are you
    comparing it to Kodachrome 25, Velvia 50 or Ektachrome 100? Agfa Ultra 100,
    Portra or Reala? Print film or transparency? The other problem is the size
    of the sensor. A compact like an Olympus E-20 will have better results than
    a point and shoot, but worse than a DSLR like a Nikon D70, even though only
    one or two megapixels separate them. And then you get into the realm of
    comparing with cameras with larger sensors, like the Canon 1Ds mkII or the
    Canon 5D, not to mention 22-40 megapixel cameras like the Hasselblad and
    Mamiya medium format bodies.
    Here's what I consider to be the easiest to comprehend breakdown of the
    whole thing, which is why I use it. The easier it is for me to comprehend,
    the better. And Roger Clark, the author, has put a lot of thought and work
    into it...
    Skip M, Feb 15, 2006
  11. Rob

    Scott W Guest

    Roger has done a lot of good work on this but it is important to not
    just look at the first plot, but to read all the article including the
    part on Apparent Image Quality. From the first plot one my believe
    that for Velvia 100 it would take a digital camera with something like
    14MP to match it, but this plot is only the resolution plot. When he
    get to what he calls the AIQ he is coming up with a DSLR having a way
    higher AIQ value then 35mm Velvia has.
    Scott W, Feb 16, 2006
  12. It rather depends on the film.

    At say 100ASA the grain in a 35mm film might manage 4,000x3,000 pixels
    (~12Mp). You need a good camera and lens to take [full] advantage.

    At 400 ASA it will be about half that, maybe less.

    In some dSLR cameras you can trade off image speed (was ASA) against shutter
    speed and aperture, giving the photographer more options.
    R. Mark Clayton, Feb 16, 2006
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