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Thread: Short DoF blur. What's the probem?

  1. #1
    whited3's Avatar
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    Short DoF blur. What's the probem?

    Hi folks.

    This image was taken with my 7D + Canon 50mm f1.4 @ 1/5000, 1.4. What causing the blur around the buds?

    I expected to have some of the buds out of focus with a DoF of ~38mm (450mm from the lens).

    Thank you in advance.


    Short DoF blur.  What's the probem?

    Short DoF blur.  What's the probem?

  2. #2
    Glenn NK's Avatar
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    Re: Short DoF blur. What's the probem?

    My first thought was chromatic aberration, but this lens shouldn't exhibit anything noticeable according to:

    http://www.photozone.de/canon-eos/15...review?start=1

    But perhaps with this colour it does happen - I really can't think of anything else, except perhaps poor bokeh.

    Glenn

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    Re: Short DoF blur. What's the probem?

    I would think you need more DOF. 1.4 is paper thin. With that lens I am thinking right around F5 maybe as far as F8 with the large size of area the flower buds cover, of course that may differ some according to how much you want in focus.


    I get this feeling I am missing something in your question here.
    Last edited by jeeperman; 24th December 2011 at 05:57 AM.

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    Re: Short DoF blur. What's the probem?

    Quote Originally Posted by whited3 View Post
    Hi folks.

    I expected to have some of the buds out of focus with a DoF of ~38mm (450mm from the lens).
    Hi Mark, I think Paul has you on the right track, as a 38mm DoF (about 1.5") ain't much when the
    flower is large. I would try it at f/3.5 on up until you captured the shot you wanted.

    Mike

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    Re: Short DoF blur. What's the probem?

    If you assume that the hydrangea flower, is 150 mm across, and your DOF @ 1.4 for 450m focal length is 38mm then about about 25% of the flower will be in focus, which appears to be about what your photo shows

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    whited3's Avatar
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    Re: Short DoF blur. What's the probem?

    Quote Originally Posted by jeeperman View Post
    I get this feeling I am missing something in your question here.
    I suppose my question is...is the blur (halo) around the buds due to the DoF or something else? I expecteded a lot of them to be unfocused but the "halo" just looks strange.

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    Re: Short DoF blur. What's the probem?

    See I was missing something. I see it now and am unsure what to make of it. Hmmmm......

    Perhaps Glenn is onto something with the Bokeh thought.....maybe it is just at that point between soft and all the way gone. Be interested to see what a few steps deeper DOF does ....one step at a time. The sharp areas don't seem to have any halo, but then I don't think I have ever seen these halos in similar images I have taken with my Minolta 50mm 1.7 in or out of the in focus area.
    Last edited by jeeperman; 24th December 2011 at 09:06 AM.

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    herbert's Avatar
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    Re: Short DoF blur. What's the probem?

    Is this an jpeg straight out of the camera? The halos could be sharpening artifacts from the jpeg processing.

    A quick check on dofmaster.com shows that for 45cm a 50 f1.4 would have a depth of field of 3.9 mm. So most of the flower will be out of focus.

    If you can then go back and shoot the flower again at multiple f-stops, and with a tripod if you have one and manual focus. This will produce a series of shots with the same focus point and you can see exactly how the depth of field expands as you move through the f-stop range. You will also see how your halos change.

    Alex

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    Shadowman's Avatar
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    Re: Short DoF blur. What's the probem?

    Even at 1/5000s the wind could be causing the buds to vibrate.

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    Re: Short DoF blur. What's the probem?

    Quote Originally Posted by Shadowman View Post
    Even at 1/5000s the wind could be causing the buds to vibrate.
    For that reason I use flash to expose my flowers. It gives me a good DoF from a small aperture, fast movement-free exposure times and, best of all, the flash doesn't reach the background which gets lost causing the real subject to stand out.

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    whited3's Avatar
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    Re: Short DoF blur. What's the probem?

    Quote Originally Posted by herbert View Post
    Is this an jpeg straight out of the camera?
    No. Taken in RAW and converted in CS5.

    Quote Originally Posted by herbert View Post
    A quick check on dofmaster.com shows that for 45cm a 50 f1.4 would have a depth of field of 3.9 mm. So most of the flower will be out of focus.
    So much for my math skills. 3.8mm, not 38mm!

    Quote Originally Posted by herbert View Post
    If you can then go back and shoot the flower again at multiple f-stops, and with a tripod if you have one and manual focus. This will produce a series of shots with the same focus point and you can see exactly how the depth of field expands as you move through the f-stop range. You will also see how your halos change.

    Alex
    Done that. I'll post them up. And yes, the halo disappears.

  12. #12
    whited3's Avatar
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    Re: Short DoF blur. What's the probem?

    @ f6.3, 1/320

    Short DoF blur.  What's the probem?

    Short DoF blur.  What's the probem?

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    Moderator Donald's Avatar
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    Re: Short DoF blur. What's the probem?

    CiC - Solutions for all problems.

    Well done, Mark. That is now a very nice image. The water droplets are wonderful.

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    Re: Short DoF blur. What's the probem?

    Nicely done Mark.

    I recall having problems myself trying to get a decent shot of some Calla Lillies in a vase.
    It took a couple sessions (and a LOT of help from the CiC folks), but finally got it right.

    3 Flowers In A Vase

    Those of us in the Northern Hemisphere sure do appreciate seeing all the fresh flowers
    growing down in AU (and NZ, too!) as it's the beginning of a long, cold and very wet
    Winter here...Short DoF blur.  What's the probem?

    Mike

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    Re: Short DoF blur. What's the probem?

    My guess is that the flower in question is an agapanthus while somewhere in the thread there was a mention of hydrangea. I'm not sure but would someone kindly tell what its actual name is ? Of course this is an off-topic excursion...
    Cheers.

  16. #16
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    Re: Short DoF blur. What's the probem?

    Hydrangea ( /haɪˈdreɪndʒⁱə/;[1] common names Hydrangea and Hortensia) is a genus of about 70 to 75 species of flowering plants native to southern and eastern Asia (China, Japan, Korea, the Himalayas, and Indonesia) and North and South America. By far the greatest species diversity is in eastern Asia, notably China, Japan, and Korea. Most are shrubs 1 to 3 meters tall, but some are small trees, and others lianas reaching up to 30 metres by climbing up trees. They can be either deciduous or evergreen, though the widely cultivated temperate species are all deciduous.

    Having been introduced to the Azores Islands of Portugal, they are now very common there, particularly on Faial, which is known as the "blue island" due to the vast number of hydrangeas present on the island, Terceira, named the "lilac island" for hydrangeas of that colour, on Flores Island ("Island of Flowers") and São Miguel, named the "green island" for its floral biodiversity.

    Species in the related genus Schizophragma, also in Hydrangeaceae, are also often known as hydrangeas. Schizophragma hydrangeoides and Hydrangea petiolaris are both commonly known as climbing hydrangeas.

    There are two flower arrangements in hydrangeas. Mophead flowers are large round flowerheads resembling pom-poms or, as the name implies, the head of a mop. In contrast, lacecap flowers bear round, flat flowerheads with a center core of subdued, fertile flowers surrounded by outer rings of showy, sterile flowers.

    A quick reply from Wikipedia. Hope it helps!

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