What compact for a DSLR user?

Discussion in 'Digital SLR' started by eatmorepies, Mar 16, 2010.

  1. eatmorepies

    Ray Fischer Guest

    So it is. I hadn't noticed.
     
    Ray Fischer, Mar 21, 2010
    #41
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  2. eatmorepies

    Doug Payne Guest

    You need to pull your head out of your inner Sisyphus and get a life.
     
    Doug Payne, Mar 21, 2010
    #42
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  3. eatmorepies

    Doug Payne Guest

    You need to pull your head out of your inner Sisyphus and get a life.
     
    Doug Payne, Mar 21, 2010
    #43
  4. []
    Thanks, Alan. BTW: I took my GPS to Greenwich, and found that zero
    degrees (GPS) no longer goes through the Greenwich Meridian:

    http://www.nmm.ac.uk/explore/astronomy-and-time/astronomy-facts/history/the-longitude-of-greenwich

    http://www.search.com/reference/Prime_Meridian

    I see the indicated accuracy on my Garmin GPS 60 CSx down to 3m, using
    WAAS.

    Cheers,
    David
     
    David J Taylor, Mar 21, 2010
    #44
  5. eatmorepies

    Ray Fischer Guest

    If that's true then what does it say about you that you need to insert
    your worthless comment?
     
    Ray Fischer, Mar 21, 2010
    #45
  6. The datum of the British Ordnance Survey National Grid System
    (OSGB36), which many GPS units in the UK will default to because that
    gives the simplest cross referencing with paper maps, has a zero some
    six metres to the west of the Greenwich Meridian. It was easier to
    shift the datum as global accuracies improved rather than to rewrite
    all the maps.
     
    Chris Malcolm, Mar 22, 2010
    #46
  7. []
    My GPS is WGS84, though, Chris, and I had to walk about 100m east of the
    meridian for the GPS to say 0 longitude. I wonder what percentage are
    WGS84 and how many OSGB36?

    Cheers,
    David
     
    David J Taylor, Mar 22, 2010
    #47
  8. eatmorepies

    Chris H Guest

    This would explain the accuracy (or lack of ) of USAAF Bombers :)
     
    Chris H, Mar 22, 2010
    #48
  9. You are right. WGS84 0 meridian is just by a dustbin where paths
    It was fun looking for it!
    I understand something of co-ordinate systems, but I don't see how you can
    get an ellipsoid wrong. Perhaps your link (for which, thanks) will
    explain it.
    Actually haven't user paper maps of any accuracy since getting the GPS 60
    CSx. I also have a 12 XL, by the way.

    What did strike me as amusing, though, was when I discovered how everyone
    copies from the Internet without checking. The locations of many cities
    can be found on the Internet - including Trondheim. However, when I
    compared my satellite image (1km resolution) with an overlay of Norwegian
    ports, it was clear that Trondheim (IIRC) was miles out - it was on the
    wrong side of the inlet. We're not talking co-ordinate system errors
    here. Naturally, I assumed it was my fault, copying the values
    incorrectly, or confusing degrees.minutes and degrees.decimal. But no,
    most of the sites I checked simply have the wrong latitude and longitude
    for that delightful town, copied from each other.

    Since then, I have taken my own GPS, and checked any latitude and
    longitude I use with at least one other source (typically Google Earth or
    Garmin's MapSource & maps).

    Cheers,
    David
     
    David J Taylor, Mar 22, 2010
    #49
  10. Impossible to say, since on many it's a user-selectable option. I
    think I can select several different datums and dozens of different
    national grids. Including I think one I can make up myself.
     
    Chris Malcolm, Mar 22, 2010
    #50
  11. But I imagine that a large, possibly very large, percentage of GPS users
    never alter the datum, or would even know what a "datum" was. It's likely
    that the as-sold state is what matters.

    Cheers,
    David
     
    David J Taylor, Mar 23, 2010
    #51
  12. Which is probably why some of the European models are sold set up as
    default with whatever the local national mapping grid datum is. I have
    a suspicion based on reading the GPS newsgroups that compared to the
    US in at least some parts of Europe the national mapping grid
    co-ordinate system is more used than Lat Long for location references.

    In the early days of GPS that 100 metre systematic offset between
    WGS84 and OSGB36 caused a lot of grief to British hillwalkers who
    hadn't read the manual, and to the emergency services when they tried
    to tell them where to come based on letters and numbers they didn't
    understand on their GPS screens :)
     
    Chris Malcolm, Mar 23, 2010
    #52
  13. Chris-

    You really become a twat when you bring in an anti- US flag at no
    provocation whatsoever. It's tiresome and rather puerile.
     
    John McWilliams, Mar 23, 2010
    #53
  14. eatmorepies

    Chris H Guest

    Well the USAFF does have a reputation for it. Though in my case it is
    personal experience. (Kurdistan 1988)
     
    Chris H, Mar 23, 2010
    #54
  15. I know that some of the road mapping GPS systems have a fixed datum
    which is unalterable, or is perhaps altered automatically by the maps
    loaded. The user can't change it or find out what it is. And I don't
    know what it is. My personal experience is with the non mapping hiking
    GPS units which are intended to be used in conjunction with local
    paper or computer-based maps.

    I have two of those, a Mk 1 Garmin eTrex Summit, and a Mk 2 eTrex
    Yellow. The Summit came set to GPS and Lat/Long, and I had to select
    the UK OS national grid and the appropriate datum to go along with
    it. Many people had problems with that because they selected the
    national grid but didn't also select the national grid datum. The
    Yellow came set up with the UK OS national grid and datum, and unlike
    the Summit, could not separate them -- if you selected the OS grid,
    the correct datum for it was automatically set.
     
    Chris Malcolm, Mar 23, 2010
    #55
  16. C'mon. You're intelligent enough to know I don't comment on the veracity
    of your anti-US barbs, most of which I agree with.

    It's that this isn't the place for it.
     
    John McWilliams, Mar 24, 2010
    #56
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