Interesting Tidbits from Canon's EF Lens Chart

Discussion in 'Canon' started by fruitbat, Jan 30, 2004.

  1. fruitbat

    fruitbat Guest

    Just took a look at Canon's updated PDF Lens Chart, and noticed a few
    things:

    - Differentiation between Ring USM and Micro USM (it's about time!)
    - Every type of USM returns distance information for E-TTL II,
    apparently.
    - Plenty of footnotes referenced, but no actual footnotes! :p

    So, they've had distance-reading capability in USM lenses for quite
    some time. Other have mentioned Nikon patents in this context, but I'm
    not clear on the specifics myself. Anyone have more insight?

    The 70-200/4L is listed on the chart as a Micro-USM, but Canon's
    website page for that lens says Ring-USM, so maybe the chart isn't
    100% accurate...

    Also, compared to previous charts, this one's formatting almost looks
    preliminary. So get it while you can, I guess, if it's worth it...

    Jeff
     
    fruitbat, Jan 30, 2004
    #1
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  2. fruitbat

    Tony Spadaro Guest

    Everything I've read says teh 70-200 f4 is ring USM. Lens brochures have
    had that information for as long as I can remember but the trouble is
    finding the brochure when I need it.
     
    Tony Spadaro, Jan 30, 2004
    #2
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  3. $- Every type of USM returns distance information for E-TTL II,
    $apparently.

    I saw a list in the Canon EOS forum at photo.net which disagrees
    with this; it lists a number of lenses which do not return distance
    information, and the list includes many micro USM and some ring USM
    lenses. There was no attribution given for the list so it may or
    may not be accurate.

    $So, they've had distance-reading capability in USM lenses for quite
    $some time. Other have mentioned Nikon patents in this context, but I'm
    $not clear on the specifics myself. Anyone have more insight?

    Canon started putting distance information in some of their lenses
    in the early 1990s, but it has been used for very little until now
    (according to the EOS FAQ, a couple of 1990s EOS bodies used it somehow
    for portrait and close-up modes).

    I don't know the specifics on the patent issue, but it has to do
    with using distance information for flash metering. Patents are
    typically quite specific, so if you can find a different means of
    using distance information to aid your flash metering, you could
    introduce your different method without having to license the
    original patent. Or you could license it, or wait for it to expire.

    $The 70-200/4L is listed on the chart as a Micro-USM, but Canon's
    $website page for that lens says Ring-USM, so maybe the chart isn't
    $100% accurate...

    The 70-200/4 is indeed powered by ring USM.

    If this is from Canon's U.S. Web site, it'll just be another in a
    long series of typos and other errors. Canon's press release for
    the 28-300 disagrees with the information in their lens listing
    regarding how many aspherical elements it has, while the lens listing
    says the 70-300 has two UD elements (which don't appear in the
    block diagram and aren't mentioned in the press release). I've
    seen information from elsewhere claiming that these two lenses have
    the circular aperture diaphragm that Canon has been using in many of
    its recent lenses but neither the lens listing nor the press release
    say anything about this.

    I have some Canon printed brochures from a few years ago that also
    have errors in them. I don't believe Canon U.S. employs proofreaders
    or fact checkers. There were some PDFs about these lenses that were
    posted a few days ago, supposedly from Canon France, and if they're
    indeed official, then apparently Canon France doesn't, either.[/QUOTE]
     
    Stephen M. Dunn, Jan 30, 2004
    #3
  4. fruitbat

    Pål Jensen Guest

    Distance information from lenses has been available from all manufacturers
    for at least a decade....
     
    Pål Jensen, Jan 30, 2004
    #4
  5. fruitbat

    Skip M Guest

    The EF lens brochure I have says the 70-200L is ring USM.
     
    Skip M, Jan 30, 2004
    #5
  6. A cursory inspection of "EF Lens Work III", suggests that all "L" lenses,
    with the exception of the T&S lens, have ring motors. Many others have
    micro-motors, or other AF systems.

    Bill Tallman
     
    William D. Tallman, Jan 31, 2004
    #6
  7. fruitbat

    Mark M Guest

    I had previously noticed that exif data from shots on the 10D include
    "distance to subject" data.
    This was a surprise to me, since I knew that E-TTL flash tech did not
    consider this.
    I had no idea this was considered until sticking my lenses on a DSLR.
    I can't remember if my old, destroyed D30 also recorded this exif tid-bit,
    but I can find out soon enough by simply calling up those images from the
    hard drive...
    ....wait...I'll look... Yep--It's there.
    Hmmm.
     
    Mark M, Jan 31, 2004
    #7
  8. fruitbat

    MikeWhy Guest

    It's there on the 300D as well, but it reports 66m for infinity.
     
    MikeWhy, Jan 31, 2004
    #8
  9. fruitbat

    Skip M Guest

    Interesting related note, distance info is recorded on my D30 with my Canon
    lenses, but not with my Tokina 28-70 f2.6-2.8...
     
    Skip M, Jan 31, 2004
    #9
  10. fruitbat

    DM Guest

    Apparently not the now discontinued 28-70/2.8L. It doesn't deliver
    distance information. The new 24-70 does, though. Bummer.
    Erm.. I have the 70-200/4L and it is ring-USM, and damn fast at that.
     
    DM, Feb 1, 2004
    #10
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