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DOF question

livefreenskilivefreenski Registered Users Posts: 163 Major grins
edited July 8, 2006 in Technique
on a shot this weekend i was trying to capture a rock skipping across a lake but it was impossible to have each puddle in focus including the airborne rock

I just had the lense that comes with the digital rebel... i tired various f-stop configs i just couldnt get this capture to work

what type of lense would I need to capture something like this because this stitition has arose a dozen times now and i like to make a purchase hahaha i just got my bonus ;)

regards
-ty

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    DanielBDanielB Registered Users Posts: 2,362 Major grins
    edited July 6, 2006
    on a shot this weekend i was trying to capture a rock skipping across a lake but it was impossible to have each puddle in focus including the airborne rock

    I just had the lense that comes with the digital rebel... i tired various f-stop configs i just couldnt get this capture to work

    what type of lense would I need to capture something like this because this stitition has arose a dozen times now and i like to make a purchase hahaha i just got my bonus ;)

    regards
    -ty

    can you give us an example shot? at f/8 it should have given you enough DOF to get all puddles in unless you were starting real low to the waterne_nau.gif
    Daniel Bauer
    smugmug: www.StandOutphoto.smugmug.com

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    NikolaiNikolai Registered Users Posts: 19,035 Major grins
    edited July 7, 2006
    Ty,
    on a shot this weekend i was trying to capture a rock skipping across a lake but it was impossible to have each puddle in focus including the airborne rock

    I just had the lense that comes with the digital rebel... i tired various f-stop configs i just couldnt get this capture to work

    what type of lense would I need to capture something like this because this stitition has arose a dozen times now and i like to make a purchase hahaha i just got my bonus ;)

    regards
    -ty

    You may need to go hyperfocal.

    I recently made a chart for myself, here's a copy:

    79572762-L.jpg

    AFAIK, it should do just fine for your DRebel.

    For instance, if you shoot at 50mm, set your aperture to f/22. Chart gives you 5.9m, roughly 6m, i.e. 18ft. This means everything from 9ft to infinity would be in focus.
    Note, that f/8 calls for 16m HF distance, i.e. 48ft, so your near DOF border will be at 24 ft, which may be too far...ne_nau.gif

    Apertures as low as f/22 may call for higher ISO, though.

    HTH
    "May the f/stop be with you!"
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    livefreenskilivefreenski Registered Users Posts: 163 Major grins
    edited July 7, 2006
    [/quote] Apertures as low as f/22 may call for higher ISO, though.

    HTH[/quote]

    yes that was the problem once i got the f-stop to the correct point the photo would be to dark. then and if i went above 1600+ with the ISO the photo would look ..... not so hot so i figure the wide angle would be easier?
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    NikolaiNikolai Registered Users Posts: 19,035 Major grins
    edited July 7, 2006
    Wide angle, ISO 1600+, etc.
    yes that was the problem once i got the f-stop to the correct point the photo would be to dark. then and if i went above 1600+ with the ISO the photo would look ..... not so hot so i figure the wide angle would be easier?

    ISO 1600+... Are you talking about 1800 or 3200?

    Well, since you didn't post or pointed to any of your shots, as well as did not specify the distance, lighting, time of day, etc, it's rather hard to recommend any change in focal length. Naturally, shortening the focal length helps to increase DOF, but that's kinda trivial fact ne_nau.gif
    Without you bringning more specifics I'm not sure if I (or anybody else) can help....
    "May the f/stop be with you!"
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    livefreenskilivefreenski Registered Users Posts: 163 Major grins
    edited July 7, 2006
    the composer on this is awful.. i had better but this is the idea
    img93199ti.th.jpg

    ISO: 800
    Shutter:1/500S
    Aperature: f4.0
    Focal Length: 75mm
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    NikolaiNikolai Registered Users Posts: 19,035 Major grins
    edited July 7, 2006
    I see
    the composer on this is awful.. i had better but this is the idea


    ISO: 800
    Shutter:1/500S
    Aperature: f4.0
    Focal Length: 75mm

    Well, Ty, I know this is not a "whipping post", but ... All this ruckus about spending $400 for a new lens - all for this? headscratch.gif
    • How about doing it in a broad daylight?
    • How about taking multiple shots and stacking them, since a calm water usually provides for a seamless blending?
    • How about throwing the stone further than a three year old, and thus gaining proper distance for the DOF?
    The possibilities for the self-improvement are endless...mwink.gif

    As a side note, instead of throwing $400 for "a" lens, I would wholeheartedly recommend to spend $250 on an academic version of PS CS2, and the rest on photography, post-processing and color-correction books.

    HTH
    "May the f/stop be with you!"
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    wxwaxwxwax Registered Users Posts: 15,471 Major grins
    edited July 7, 2006
    the composer on this is awful.. i had better but this is the idea
    img93199ti.th.jpg

    ISO: 800
    Shutter:1/500S
    Aperature: f4.0
    Focal Length: 75mm

    Hold the lens in landscape mode (long side up) and angle it so your skip goes from one corner of the frame, across the diagonal, to the other corner.

    Try f11, maybe f16. Give yourself whatever ISO you need, in order to raise your shutter speed to about 1/200th or faster.

    Prefocus on where you think the first skip will be, so you're not asking your autofocus to do too much work.

    Once you've nailed a few shots with these techniques, start slowing down your shutter (and lowering your ISO to compensate) so you can get some motion blur on your rock.

    No need to spend a few hundred dollars on a lens.

    That Nik, he's a nasty one, eh? lol3.gif
    Sid.
    Catapultam habeo. Nisi pecuniam omnem mihi dabis, ad caput tuum saxum immane mittam
    http://www.mcneel.com/users/jb/foghorn/ill_shut_up.au
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    NikolaiNikolai Registered Users Posts: 19,035 Major grins
    edited July 7, 2006
    Sid,
    wxwax wrote:
    No need to spend a few hundred dollars on a lens.
    My point exactly mwink.gif
    wxwax wrote:
    That Nik, he's a nasty one, eh? lol3.gif
    I sure can be, pardner! :D
    "May the f/stop be with you!"
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    erich6erich6 Registered Users Posts: 1,638 Major grins
    edited July 8, 2006
    With the kit lens try shooting at the shorter focal lengths (wide) and get closer to the action. That'll give you a better sense of depth and direction in your perspective and will help increase your DOF. I think you can get this at 17 mm with ISO 400 at f/8 to f/11 if you wait for decent lighting. You could get improved lighting with more direct sunlight or waiting for some fog/haze around the water in morning/evening sun.

    If you absolutely have to have higher ISO's I recommend getting the DxO software. This will cost you less than a new lens and will make your kit lens output look great plus buy you a couple of stops with its noise reduction.

    Erich
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