dslr vs 35mm film lens viability

Discussion in 'Digital SLR' started by Denton, Jan 27, 2006.

  1. Denton

    Denton Guest

    Hi all...
    I have started to put together a lens collection to use with my new Rebel
    XT. Currently have the kit lens, a 100-300mm usm, 50mm f1.8, 24mm f2.8 and
    have a 20-35mm usm lens comming. Other than the 100-300 lens and the kit
    lens, the other ones seem to be rated fairly highly.
    What I am trying to determine is the lens quality is more critical in terms
    of picture quality for a 1.6 dslr sensor vs. a full frame dslr sensor or
    35mm film body.
    It seems to me that the lens quality would be more critical for smaller
    sized dlsr sensors.
    Denton, Jan 27, 2006
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  2. Denton

    Steve Wolfe Guest

    I have started to put together a lens collection to use with my new Rebel
    The smaller the individual photo receptor sites, the higher resolution
    you need from a lens. That's one of the reasons for going full-frame - as
    an example, the 5D, even with 12 megapixels, still has larger receptor sites
    than the 20D at 8 mp. Because of that, you don't need *quite* as much
    resolution from your lens.

    This really shouldn't surprise anyone with more than a passing familiarity
    with photography, since going to a larger negative has, since the inception
    of photography, been the method for obtaining greater detail despite
    limitations in both optics and film. To put some numbers to it, some of the
    dSLR sensors today are theoretically capable of resolving 100 lp/mm. If you
    look at the gigapixel project, their design goals were, I believe, just a
    modest 30 lp/mm or 40 lp/mm over the film plane - but because there's such a
    large film plane, that works out to nearly unfathomable amounts of recorded

    If you want to compare the resolution requirements of film and digital, it
    depends on what kind of film you're talking about. If you're shooting some
    400-ISO film that you bought at the supermarket, then the digital sensor
    will provide far more resolution, and hence take more advantage of a
    high-quality lens. If you're talking about an ultra-fine grain, low-speed
    slide film, then it's going to have the capability to resolve more than all
    (or nearly all) dSLR cameras today.

    It should also be noted that in the situations under which most
    photographs are taken, an increase in resolution of either the lens or the
    film/sensor won't do any good, because the camera movement and/or other
    factors (such as diffraction) will limit the overall resolution anyway.

    As for your DR XT, you're not wasing good glass on it, sticking a good
    lens on it isn't going to disappoint. Besides, there are lots of
    differences between a mediocre lens and a good lens other than just
    resolution. Even getting aside from the non-visual aspects such as build
    quality and autofocus speed, you still have contrast, color, resistance to
    flare, the quality of bokeh, the shape of the aperture (visible in
    out-of-focus highlights), barrel/pincushion distortion, presence (or lack)
    of coma, astigmatism, spherical aberration, and various other deficiencies.

    Steve Wolfe, Jan 27, 2006
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  3. Once more we see the urban legend of different lenses for digital than

    Just get the best lenses out there and don't worry about it. Your
    lenses are going to be better than you are for a long time.


    "A combat photographer should be able to make you see the
    color of blood in black and white"

    David Douglas Duncan
    Speaking on why in Vietnam
    he worked only in black and white
    John A. Stovall, Jan 27, 2006
  4. Denton

    wilt Guest

    What I am trying to determine is the lens quality is more critical in terms
    of picture quality for a 1.6 dslr sensor vs. a full frame dslr sensor
    35mm film body. It seems to me that the lens quality would be more
    critical for smaller
    sized dlsr sensors. <<

    Lens quality should have a correlation simply to FRAME SIZE as has been
    proven in 100 years of film photography...a large format lens does not
    need nearly as high spatial resolution performance as a microfilm lens!

    In the context of crop vs. FF digital, the factor is that crop uses
    LESS of the image circle of an lens than FF format, so the lens need
    not perform as highly out at the edges of the image circle. So smaller
    is less demanding in this regard!
    wilt, Jan 27, 2006
  5. Denton

    wilt Guest

    Neglected also to deal with the issue that wider lenses are needed to
    get same FOV in crop format as in FF format. And wider lenses seem to
    exhibit more Chromatic Abberation, so if you want to have less CA
    appear in the frame you need better correction in the lens design.
    wilt, Jan 27, 2006
  6. Denton

    cjcampbell Guest

    I see this said a lot, but so far I have had to take the word of people
    on this board for it. Are there really any comparison shots with film
    vs. DSLR that prove this?
    cjcampbell, Jan 28, 2006
  7. Denton

    Skip M Guest

    Not a comparison of images, but you might find this informative:
    Skip M, Jan 28, 2006
  8. Denton

    Alan Browne Guest

    Beyond resolution (Wolfe and wilt replies), there are other qualities in
    higher end lenses which include build, faster apertures, constant
    aperture with zoom, internal zoom and focus, color rendition, proneness
    to vignetting (no issue with 1.6x crop), proneness to flare and some
    others I've likely missed. Avoid high ratio zooms.

    Since cameras continue to rise in resolution, and at least with Canon
    there are FF sensors, it makes sense to err on the side of resolution
    and all qualities that improve the image in your lens selections.

    With the D200 touting 10 Mpix, and rumors of a new "prosumer" Canon
    ahead of PMA 2006, moreso. Even if you're happy with 8 Mpix, you _know_
    you'll be lusting for 10 or 12, or whatever Canon do.

    Alan Browne, Jan 29, 2006
  9. [/QUOTE]

    And anyway, there is no grain on slide film. :p

    (ducks and runs). :)

    All the best,
    Angus Manwaring. (for e-mail remove ANTISPEM)

    I need your memories for the Amiga Games Database: A collection of Amiga
    Game reviews by Amiga players http://www.angusm.demon.co.uk/AGDB/AGDB.html
    Angus Manwaring, Jan 29, 2006
  10. Denton

    Stacey Guest

    John A. Stovall wrote:

    And you know this because?
    Stacey, Jan 29, 2006
  11. Because, if he was that good, he wouldn't be posting here.


    "It looked like the sort of book described in library
    catalogues as "slightly foxed", although it would be
    more honest to admit that it looked as though it had
    been badgered, wolved and possibly beared as well."

    _Light Fantastic_
    Terry Pratchett
    John A. Stovall, Jan 29, 2006
  12. Denton

    Stacey Guest

    So then by your logic, any lens is better than someone who posts to a
    photography forum? Sorry I don't buy that one as you have no idea if this
    guy can take good photographs or not.
    Stacey, Jan 29, 2006
  13. Denton

    Jeremy Nixon Guest

    I think a more precise statement would have been "Because, if he was that
    good, he wouldn't be posting *that question* here."
    Jeremy Nixon, Jan 29, 2006
  14. Denton

    Steve Wolfe Guest

    If you want to compare the resolution requirements of film and digital,
    I wasn't able to find links to the images I've seen, but in real,
    well-designed apples-to-apples tests, the best slide films have
    out-performed the dSLR images. I'll keep my eyes open and see if I can find
    them again. So many of the comparisons are poorly thought out or executed.

    Steve Wolfe, Jan 30, 2006
  15. Denton

    Stacey Guest

    Still don't buy that.

    A really good photographer might easily ask that same question. You can say
    in one way it's easier to design a good lens for a small sensor and it
    other ways it's harder. One lens might have great central performance (and
    poor edges) and work good on a crop dSLR, and another that is better across
    the whole full frame might not be as good in the center. There is no cut
    and dry answer to the question. To say "Buy expensive lenses and they will
    be better than you" is a silly statment and explains nothing.
    Stacey, Jan 31, 2006
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