isolate object

Discussion in 'Photography Beginners' Forum' started by akazoly, Jan 4, 2008.

  1. akazoly

    akazoly TPF Noob!

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    I want to capture a flower, or something and isolate the subject. I want to see blur in background.

    I set my Nikon 18-55 lens to 18 and F3.5. I try to capture the subject but I don't see blur in background, why ?
     
  2. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    The effect you are looking for is a result of a shallow DOF (depth of field).

    Setting your aperture to your lens's max, is a good start. It will also help if you zoom the lens out to the max.

    Also, the distance between the subject and the background will also affect how the out of focus areas (called Bokeh) look. If you can, shoot at an angle that puts the background as far away as possible and get as close to the subject as you can.

    Getting a shallow DOF is easier with a lens that has an even bigger aperture. Something like F1.8 or F1.4 etc.
     
  3. akazoly

    akazoly TPF Noob!

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    I need a big distance between subject and background at F3.5 ? 2-3 metre or more ?
     
  4. Mav

    Mav TPF Noob!

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    The longer your focal length, the tighter the DOF will be. And the larger your aperture (smaller f/number), the tighter the DOF will be. And the closer you are to the subject, the tighter the DOF will be also.

    Since the 18-55 doesn't have either a very long focal length or a large aperture, it's pretty difficult to get subject isolation with it, and even when you do, the results aren't exactly going to be creamy smooth either. But on that particular lens, reframe your flower so that you're zoomed all the way to 55mm, get closer to the flower, and make sure the lens aperture is set wide-open, which is f/5.6 on that particular lens. That'll probably give you a tighter depth of field than when framed at 18mm and f/3.5.

    I'll try to post some examples later.
     
  5. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    The more the better.
    Can you take it outdoors? Then maybe the background would be 10-20m or more. That would definitely help.

    F3.5 just isn't very big...maybe go out and buy yourself a 50mm F1.8.
     
  6. Mav

    Mav TPF Noob!

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    A sample from my 18-55 at 55mm and f/6.3. This was shooting at some low branches with higher ones blurred in the background. Program auto mode.

    [​IMG]


    Yes, a large distance between your subject and the background will be of great help to the lil 18-55. :)
     
  7. akazoly

    akazoly TPF Noob!

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  8. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    That lens will certainly allow you to get a very shallow DOF. Also, the large aperture will allow you to get faster shutter speeds, which is good for shooting handheld in lower light and/or stopping action.
     
  9. Puma

    Puma TPF Noob!

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  10. Mav

    Mav TPF Noob!

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    Yep, that's the one.

    Here's an extremely crappy example, but on this leaf shot you can see the center in focus, and both the front and back edges out of focus. This was at or near close focus distance and f/1.8

    [​IMG]


    This is at f/4

    [​IMG]


    Before you pull the trigger on that, though, keep in mind that it doesn't focus all that closely, which can be a bit of a problem for floral photography. The reproduction ratio is only 1:6.6 or something on the 50/1.8 which leaves you pretty far away. I had good success with the 55-200mm lens which focuses much more closely at 1:3.5 (1:4.2 for the VR version).

    Here's two samples from that:

    120mm @ f/8

    [​IMG]


    135mm @ f/6.3

    [​IMG]



    For that last one, below is the tree I was shooting. If you look closely on the left you can make out the specific branch I was shooting, and about the angle and distance between that and the fairway (side of a golf course)

    [​IMG]



    A better lens than either of these for floral photography is a 55 or 60mm f/2.8 micro, for about $300 used or so. These will close focus all the way down to 1:1 which will give some outstanding floral shots, if you do this sort of thing regularly. I've also read elsewhere that a Kenko 12mm extension tube on the 50mm f/1.8 will help it get a ton closer. I've seen some great examples of that too, but have not personally ever tried it. I saw a Kenko tube set used for dirt cheap but hesitated and then somebody else beat me to it. :mrgreen:
     
  11. Stratman

    Stratman TPF Noob!

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    Here's a shot of some roses with my SMC-M 50mm F 1.4 @ F1.4, I like the bokeh on this shot, i was about as close as i could get to the in focus rose, and it produced a nice result. Love the bokeh on this old lens !!

    [​IMG]
     
  12. LoKaM

    LoKaM TPF Noob!

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    I love that picture of your dog Puma.

    It's almost like it's in 3D
     

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