TR: Beacons Today

Discussion in 'General Fitness' started by Paul Saunders, Dec 19, 2004.

  1. ste®

    ste® Guest

    "W. D. Grey" <[email protected]> wrote in message
    news:[email protected]
    | In article <[email protected]>, ste®
    | <[email protected]> writes
    | >Yes, I guess we can't appreciate how wide it is, not knowing the area.
    But
    | >I guess you're well pleased at the 'wideness' of your lens? After xmas,
    | >I'll be weighing up a Sigma 12-24 v Canon 10-22... (I'm sure the Canon
    will
    | >win, but I'd rather wait for LL to post their results, once he gets a new
    | >lens that is!)
    | Have a look at this link
    |
    | http://www.luminous-landscape.com/reviews/lenses/Canon-10-22mm-test.shtml
    | --
    | Bill Grey
    | http://www.billboy.co.uk

    Thanks Bill. I have read that, but it only made me eager to see the
    shoot-out between the two lenses. It's obvious from the comparison shot
    between the 10-22 and the 12-24 that the 12-24 is either much worse, or more
    likely, he's got a dud model (as per the notes on the bottom of the page).

    I'll have a google as there must be other lens testers out there.

    Ste
     


  2. W. D. Grey wrote:

    > Try 20 secs (Aperture priority) at f 8 and check the histogram.
    > Digital is so user friendly :)


    That would come out almost black in those conditions!

    The easiest way to do it is to whack the film speed up to max (either
    1600 or 3200), set the aperture to the widest, then do a few quick test
    shots. Once you've determined the optimum exposure, reset the film
    speed and aperture to sensible values, then calculate the necessary
    shutter speed. Then take the pic!

    Paul
    --
    http://www.wilderness-wales.co.uk
     
  3. Judith wrote:

    > Nice photo. The surface of the water wasn't like that when Bill and I
    > were there last month!


    I bet it wasn't! I've only once camped there when there were serious
    waves across the lake.

    Paul
    --
    http://www.wilderness-wales.co.uk
     
  4. W. D. Grey wrote:

    > Excellent shots Paul, I particularly likes /38 46, and a few more
    > lakeside ones but my fav is 82 - the first night shot.


    Ah, so you liked 38 in spite of the flat light? Presumably the
    composition. I must take that in better light.

    > I look forward to giving my lens a work out.


    I'm sure you do!

    Paul
    --
    http://www.wilderness-wales.co.uk
     
  5. Phil Cook wrote:

    > Hey these are really great. Have you thought of blending two shots for
    > these long exposures? One very long exposure for the land and one for
    > sky that keeps the stars as points?


    Oddly enough I didn't, but it's a very good point. I shall bear it in
    mind for next time.

    > As for footprints it depends on where they are, sometimes a few can
    > add to a photo. It's nice to have the option of adding a few yourself
    > but I admit there are rather too many by the Llyn.


    Yeah, too many visitors early in the day, unavoidably passing the SE
    corner of the lake. At least I had the most of the lakeside to myself.
    Being the first to break the snow around the lake made the walking a lot
    harder, but at least I was able to choose viewpoints carefully without
    ruining the snow.

    Probably the first and the last to circumnavigate the lake in that snow,
    it's gone now...

    Paul
    --
    http://www.wilderness-wales.co.uk
     
  6. W. D. Grey

    W. D. Grey Guest

    In article <[email protected]>, Paul Saunders
    <[email protected]> writes
    >
    >> Try 20 secs (Aperture priority) at f 8 and check the histogram.
    >> Digital is so user friendly :)

    >
    >That would come out almost black in those conditions!


    maybe - but the principle is right.
    --
    Bill Grey
    http://www.billboy.co.uk
     
  7. W. D. Grey

    W. D. Grey Guest

    In article <[email protected]>, Paul Saunders
    <[email protected]> writes
    >W. D. Grey wrote:
    >
    >> Try 20 secs (Aperture priority) at f 8 and check the histogram.
    >> Digital is so user friendly :)

    >
    >That would come out almost black in those conditions!


    Both Paul and I missed my faux pas above ..!

    I should have said try Aperture priority f 8 and check the histogram.

    You can't set 20sec in Aperture priority - you set the aperture. The
    camera decides the shutter speed.
    --
    Bill Grey
    http://www.billboy.co.uk
     
  8. W. D. Grey wrote:

    >>> Try 20 secs (Aperture priority) at f 8 and check the histogram.
    >>> Digital is so user friendly :)

    >>
    >> That would come out almost black in those conditions!

    >
    > Both Paul and I missed my faux pas above ..!
    >
    > I should have said try Aperture priority f 8 and check the histogram.
    >
    > You can't set 20sec in Aperture priority - you set the aperture. The
    > camera decides the shutter speed.


    Quite! Also, aperture priority decides the exposure, whereas the whole
    point of checking the histogram afterwards is for a manual exposure.

    Since night shots usually require longer exposures than 30 seconds, you
    have to use the B setting. I haven't checked, but I suspect the B
    setting only works in manual mode, for obvious reasons.

    Again, if testing night exposures, start with the widest aperture and
    highest ISO rating to quickly determine the correct exposure, then
    change to a lower ISO and smaller aperture and compensate the shutter
    speed accordingly. This probably could be done using aperture priority,
    but you'd still have to check the histogram and correct if necessary,
    then switch to manual mode for the longer exposure.

    An important point about apertures and star trails. As we know, a
    smaller aperture is compensated for by a longer shutter speed, so no
    matter how small the aperture, we can make the scene as bright as we
    want by increasing the exposure time (longer shutter speed).

    However, when photographing stars, this is only true up to a point.
    That point (if you excuse the pun) is when the apparent movement of the
    stars starts to create a trail, so you get a line rather than a point of
    light. Since the stars move (I know it's not really the stars moving),
    a longer exposure time won't make a star any brighter once it's moved to
    a different position. Therefore, the aperture you use determines the
    maximum brightness of the stars, and consquequently the limiting
    magnitude (the faintest stars that can be seen).

    So if you want the brightest stars (and more faint stars), you'll need
    to use the widest aperture. Using f8 may give you better depth of
    field, but f4 will give you more and brighter stars.

    In fact, I read that for this kind of night photography you should use
    the widest aperture, in spite of the widest aperture usually producing a
    lower quality image. In fact, if you're really serious about night
    photography, it would be best to use fixed focal length lenses with very
    wide apertures. A 50mm f1.4 lens would be superb for this, although not
    very wide (80mm equivalent). You can get a 35mm f2 I believe, and maybe
    even a 28mm f2, but they're not cheap and still not very wide on a DSLR
    (28 is equivalent to 45). I don't think wider lenses go as bright as
    f2.

    With this in mind, my Canon G3 was rather good with its f2 lens,
    equivalent to 24mm with the wide-angle adapter. Unfortunately there was
    a maximum of only 15 seconds exposure time and no B setting, so no good
    for star trails.

    Currently I think the the most practical option for DSLR night
    photography is the new Sigma 18-50 EX lens, which is f2.8 throughout the
    whole range. Not as bright as the fixed lenses, but considerably
    cheaper and reasonably wide, and of course it's a zoom, saving money
    weight and bulk on a collection of fixed lenses.

    One more thing, there's a rule for star trails, the 600 rule. If you
    divide 600 by the focal length (equivalent focal length for digital),
    that's the maximum number of seconds you can expose for before trails
    start to appear, so for example;

    600mm lens - 1 second
    300 - 2 secs
    200 - 3 secs
    135 - 4.4 secs
    80 - 7.5 secs
    50 - 12 secs
    35 - 17 secs
    24 - 25 secs
    16 - 37.5 secs

    These exposure times, combined with the widest f-stop, will give you the
    brightest possible stars without trails appearing.

    Oh, and for best results, choose a moonless night and a location far
    away from city lights.

    Paul
    --
    http://www.wilderness-wales.co.uk
     
  9. W. D. Grey

    W. D. Grey Guest

    In article <[email protected]>, Paul Saunders
    <[email protected]> writes
    >Oh, and for best results, choose a moonless night and a location far
    >away from city lights.


    Kingsway Roundabout - I think not :)

    It is surprising how small the distance you have to travel can be to
    achieve the required unpolluted darkness.
    --
    Bill Grey
    http://www.billboy.co.uk
     
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