Difference between lenses for film and lenses for digital?

Discussion in 'Digital Photography' started by One4All, Jan 7, 2007.

  1. One4All

    One4All Guest

    Is there a difference between lenses made for photographing with film
    vs. digital photographing? I've read that there is. I ask because I
    want to buy one of the new Pentax K cameras that will allow me to use
    my film lenses. If there is a difference, is it so small as to make the
    issue irrelevant?
    One4All, Jan 7, 2007
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  2. One4All

    bluezfolk Guest

    AFAIK they are the same, but the film lenses focal lenghts are based on
    the diagonal of the film size which may not be the same as the sensor
    size (then again it may) so there may a discrepsancy in the focal
    length. Thats why you always see digital zooms showing their 35mm
    equivalant (which is what people are used to). If I were you I'd use
    my film lenses on the digital.

    bluezfolk, Jan 7, 2007
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  3. Digital sensors reflect more light than film, so "digital" lenses may have
    different coatings, element shapes etc. to minimise any ghost images caused
    by the light reflected off the sensor surface. It's not a new phenomenon -
    I can find decades old slides where bright point images against a dark
    background have their duller ghosts imaged quite clearly. Good for the
    marketing types to have something "new" and attractive for us.
    Malcolm Stewart, Jan 7, 2007
  4. For DSLRs, the basic rule is that _most_ digital lenses can't be used with
    film, and that _most_ film lenses can be used with digital.

    (Aside: Old Canon manual focus lenses are essentially unusable on any AF
    Canon body (film or digital), and Nikon is an amazingly confusing can of

    My understanding is that Pentax is one of the better companies in terms of
    supporting old film lenses. You should be able to use both your Pentax 67
    and Pentax 645 lenses just fine (as I understand it: I went Mamiya and not
    Pentax for my MF work, and my Mamiya 645 lenses are sort of usable on my

    But you need to "read the fine print". The Dpreview Pentax discussion forum
    should be able to answer specific questions.


    David J. Littleboy
    Tokyo, Japan
    David J. Littleboy, Jan 7, 2007
  5. $Is there a difference between lenses made for photographing with film
    $vs. digital photographing? I've read that there is. I ask because I
    $want to buy one of the new Pentax K cameras that will allow me to use
    $my film lenses. If there is a difference, is it so small as to make the
    $issue irrelevant?

    There are a couple of technical differences.

    One of the technical differences is that most DSLRs have sensors
    which are substantially smaller than the 35mm film frame. Lenses
    designed for use on 35mm bodies have to project an image circle
    which is large enough to cover the 35mm frame; lenses designed for
    digital cameras can get away with projecting a smaller image circle,
    and that can make the lens smaller and lighter than an equivalent
    lens for a 35mm camera would be. (It should also be cheaper, as it
    requires fewer raw materials, but the reduction in materials costs
    doesn't always make it through the production, marketing, and
    distribution process to the end user.)

    The other is that digital sensors tend to be more reflective than
    film. Lenses include anti-reflection features, but in the film days,
    these were primarily to cut down on problems caused by light reflecting
    off surfaces within the lens itself. On a digital body, light
    reflecting off the sensor is another issue, and so digital lenses
    typically take additional anti-reflection measures designed to
    reduce the impact of such reflections.

    That said, lots of us use "film" lenses on our DSLRs with great
    results, which goes to show that a substantial part of the reason
    for existence of "digital" lenses is marketing rather than technical.[/QUOTE]
    Stephen M. Dunn, Jan 7, 2007
  6. One4All

    nick c Guest

    According to Canon there is a difference, how much of a difference or
    does the difference matter in the real world is debatable. Canon makes
    lenses they label as DO. These lenses direct light entering the sensor
    differently than conventional lenses. Conventional lenses direct light
    in an angular manner with is suitable for film but not as well suited
    for a sensor.

    Does it really matter? Will photographic differences be obvious? Not
    that I can see in a finished print. At this time, in availability of
    lenses and lens design, I think it's irrelevant.
    nick c, Jan 7, 2007
  7. One4All

    Chuck Dubois Guest

    Is there an adapter that will allow the use of lenses from other brands on
    a Canon 20D? Is there any place to buy quality used lenses?
    Chuck Dubois, Jan 7, 2007
  8. One4All

    Ken Lucke Guest


    You need only reflect that one of the best ways to get yourself a
    reputation as a dangerous citizen these days is to go about repeating
    the very phrases which our founding fathers used in the struggle for
    -- Charles A. Beard
    Ken Lucke, Jan 7, 2007
  9. One4All

    One4All Guest

    Thanks to all for their very relevant information.
    One4All, Jan 7, 2007
  10. One4All

    Steve Wolfe Guest

    Is there a difference between lenses made for photographing with film
    According to the "Eyes of EOS" book, there is one possible difference.
    Without going into technical detail, there are design characteristics of
    particular individual elements within the lens which can make the lens
    slightly more prone to flare *if* something is reflected back into the lens
    from the film plane. Because digital sensors are more reflective than film,
    Canon says that they have gone out of their way to produce lenses with more
    appropriately-curved elements to reduce that phenomenon. There is also
    consideration as to the coatings on individual elements, there is a pretty
    wide range of combinations of which elements get coated in what ways, and
    with what materials. (That can also infuence the color balance as well
    resolution or flare.)

    That being said, *good*, modern lenses (even those that weren't "designed
    for digital") don't really seem to display more flare with digital than they
    do with film, so there is evidence that if you're buying decent lenses to
    begin with, there's nothing to worry about. Cheap lenses with particularly
    bad design or particularly cheap coatings may show a bit more flare with
    digital, but such lenses are going to be poor-performers even with film.

    More than anything else, "designed for digital" seems to simply mean "This
    lens has a smaller image circle, so it won't work on a film or full-frame
    camera." (Perhaps unless you're buying bottom-of-the-barrel lenses anyway,
    in which case, you're screwed anyway.)

    Steve Wolfe, Jan 7, 2007
  11. One4All

    Paul Mitchum Guest

    In the case of Pentax lenses, you can use all K-mount lenses that have
    an A setting on the aperture ring, or which don't have an aperture ring.
    And even if they don't have an A setting on the aperture ring, you can
    change a custom setting to allow you to use the aperture ring instead of
    the thumb wheel to set aperture.

    Pentax is making digital-only lenses now ('DA' in the nomenclature), but
    the only real difference is that they produce a smaller image circle,
    since the digital sensor is smaller than film. This means you'll likely
    get vignetting if you use a digital-only lens on a film body. But other
    than that, and with the caveats that have always been true of FA-J
    lenses, there's no mechanical reason why you couldn't do it.
    Paul Mitchum, Jan 7, 2007
  12. One4All

    Einst Stein Guest

    This is the question that I am still getting new inputs from time to
    time. I only get to learn some more after I hit the problem. Here's
    what I learned so far, but may need to be corrected.

    1. nonuniform color-shift or vignet:

    With some low end (midiumn format) digital sensors, some lenses
    (partticularly in wide angle?) that work fine for films may show
    visible non-uniform color shift or vignet.
    One cause of this is the microlenses on the sensor. The
    micro-lenses imposed extra directional sensitivity, that the sensor
    elements at the cornor couldn't receive equal amount light compared to
    the elements in the center. This problem had not happen on films, and
    this problem would not shown on high end digital back. For example, I
    heard that PhaseOne P25 or P45 are types that have no problem, but
    P20/P21 may. Also, I heard all current 35mm FF digital cameras behaves
    more like P20 that P25, and should be much worse.
    This problem is usually much less in tele-lenses.

    2. Light spectrum sensitivity:

    The digital sensor has quite different wave-length sensitivity than
    films. Some lenses designed for digital era are taking care of this
    issues by different coating. I heard Carl Zeiss's new lenses (ZF) is an
    example in dealing with this problems. I can expect newly release
    lenses from Canon or Nikon may start to follow the similar practise. I
    don't have true experiences on these new lenses, so you'll need to
    search more to see if this is supported. -- but you need to take this
    more serious when choosing the filters, For example, while warmer (1A?)
    filter commonly apprears as the standard protection filter on film
    camera, you might find the neutral-er filter is more common on digital
    Einst Stein, Jan 7, 2007
  13. One4All

    Rich Guest

    Properly designed lenses for sensors differ from film lenses. They are
    telecentric, meaning the light rays enter the sensor surface as
    perpendicular as possible. This has to be compared on a case by case
    basis. However, people saying old 35mm film lenses will "vignette"
    aren't very clear on the concept. Vignetting is caused by light fall
    off at the edges of a lens's field. 35 mm lenses because they were
    made to produce an image circle 35mm or more across do well in that
    respect with smaller than FF digital sensors. Here is an example.
    Where they can fall down in performance (one area) concerns chromatic
    aberration. Most older lenses don't use ED glass and other elements
    needed to control this, so you end up with the blue fringing on
    bright-dark interfaces. What was acceptable with film is not with most
    digital sensors. But, ED glass costs money and cheap lenses are made
    to be cheap. Which is also why you see colour error showing up on most
    cheap P&S images.

    The real problems occur when poor quality film lenses are used on FF
    (Canon) sensors. The edge definition is terrible, showing all kinds of
    aberrations from CA to SA to coma. In this case, eventually the camera
    maker will have to create lenses designed to accommodate such a large
    Rich, Jan 7, 2007
  14. One4All

    Bryan Olson Guest

    "DO" here is "Diffractive Optics", which allows long-focus lenses
    to be physically smaller. It has essentially nothing to do with
    digital vs. film.
    Bryan Olson, Jan 7, 2007
  15. http://photonotes.org/articles/eos-flash/ says:

    TTL flash metering works by measuring the pulse of flash-generated
    light bouncing back off the subject and entering the lens. It
    actually measures this light reflecting off the surface of the
    film itself, in realtime, by using an off the film (OTF) sensor.
    The light from the flash bulb is quenched when the sensor
    determines enough light has been produced to achieve a
    satisfactory flash exposure to get a mid-toned subject. Since
    digital cameras do not have film, digital EOS cameras do not
    support TTL.

    So given digital sensors are more reflective than film, why is the
    same trick not used for flash metering?
    Richard Kettlewell, Jan 7, 2007
  16. One4All

    Toby Guest

    The problem comes using a DX lens on a film camera, because the image circle
    on such lenses is to small to cover the larger size of film (as compared to
    the digital sensor). It is generally perfectly fine to use lenses for 35mm
    cameras on DSLRs. Your effective focal length, as Eric says, will be ~1.5x
    that for a film camera. So a 50mm lens used on a DSLR will give you the same
    field of view as a 75mm lens on a full-frame 35mm film camera. This is great
    with telephotos, as your 300mm f4 film lens suddenly gives you the same
    frame as a 450mm f4 would :)

    It is not so great with wide angles, because your 20mm lens suddenly becomes
    equivalent to a 30mm lens :-(

    My suggestion is to buy one DX lens at the short end (like a 12-24mm or
    10-20mm) and use your present film lenses for everything else. I'm not
    familiar with Pentaxes, so be sure that your lenses are compatible with the
    new body. For instance with Nikon, if you don't have modern lenses that
    include a CPU you won't be able to meter on the cheaper DSLR bodies. I don't
    know if there is a similar caveat with Pentax lenses.

    Toby, Jan 7, 2007
  17. One4All

    tomm42 Guest

    (Aside: Old Canon manual focus lenses are essentially unusable on any
    Canon body (film or digital), and Nikon is an amazingly confusing can
    OK the Canon FD lenses can't be used for digital, the Canon mounts are
    completely different. Nikon is hardly a "can of worms" the only lenses
    that can't be used on Nikon digital are the pre 1980 lenses that don't
    have meter controls, all AI or AIS lenses can be used on digital Nikon
    bodies. The new D40 does throw things off a bit, be cause it requires a
    motor in the lens to autofocus. But still AI and AIS lenses can be
    There is really no reason not to use film lenses with digital, using
    digital lenses on film may create some problems as they are designed to
    cover the smaller APS sensor. 35mm framed digital cameras will have the
    same problem with APS sized digital lenses, digital lenses maybe
    problematical for 1.3x sensors from Canon and older Kodak DSLRs, so
    film lenses maybe your only solution here too.
    Unless the film lens is too old for the camera, Nikon, Canon, Pentax
    (may need adapters that don't let the lens function fully) or
    Minolta/Sony (older nonAF Minolta lenses). I don't think any of the
    manufacturers have any restriction on any AF lenses (except the Nikon
    My film designed Nikon 55 f 2.8 micro has to be one of the sharpest
    lenses I have ever used, all the rest of my lenses are "film lenses"
    and there is no problem on my D200. Two are pre autofocus, and work

    tomm42, Jan 7, 2007
  18. Supposedly some of the lenses designed for digital have the rays in
    image space (between rearmost surface of lens and image plane) more
    nearly parallel to optical axis than film lenses because CCD chips are
    a bit less sensitive to light striking the chip at extreme angles.
    This is only really an issue with very short focal length large
    aperture lenses (wide FOV and low f/#).

    Since the falloff with either type of "sensor" is pretty severe anyway,
    I don't worry about it much- also because I am not a fan of extreme
    wide angle shots.
    Don Stauffer in Minnesota, Jan 7, 2007
  19. One4All

    King Sardon Guest

    Supposedly, the "digital" lenses are telecentric, yet they also have a
    close backfocus. IMHO those are conflicting requirements.

    King Sardon, Jan 7, 2007
  20. One4All

    Bill Funk Guest

    Are you sure?
    Since the OP is speaking about DSLRs, he's asking about the difference
    between older lenses that aren't defined as being designed for DSLRs,
    as opposed to those that are labeled as designed for DSLRs.
    In that case, the focal lengths are the same, and (except for the case
    of Canon's EF-S lenses) can be used on film SLRs, but many will
    vignette. The focal lenght, though is the same, whether the lens is
    designed for DSLRs or not. Thus, a 50mm lens designed for a DSLR is
    the same focal length as a 50mm lens not designed for a DSLR.
    Where you see 35mm equilivents are in cameras with fixed (not
    removable) lenses (such as P&S cameras) which actually have lenses
    with (usually) shorter focal lengths suited to the smaller sensers
    these cameras have.

    The Coney Island Polar Bear
    Club hosted its annual New
    Year's Day swim in the frigid
    waters off New York City Monday.
    It wasn't completely successful.
    Paris Hilton and Britney Spears
    came out of the water just as
    drunk as when they went in.
    Bill Funk, Jan 7, 2007
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