Blur background with kit lens

Discussion in 'Sony Cameras' started by robbyrob, Feb 20, 2012.

  1. robbyrob

    robbyrob TPF Noob!

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    Ok I am a noob at photography and never realized the thinking that went into taking some of the awesome pictures I have seen here. I see most portraits have blurred background. I have been reading my manual and specs on most pic in flickr and see that most pics were shot with a low aperture of f1.2 to 2.4. Reading another thread on here of prime lenses I saw a link to a page which showed a picture shot by a cannon at f3.5 which had the background blurred. This leads me to beleive I can get the same effect with my kit lens.

    Ive tried to shot in A mode at f3.5 but it doesn't seem to come out with background blurred. any tips you guys can give me or something I could be missing. I try to focus on one item of person but photo comes out all in focus. I was thinking maybe changing my focus to single focus and maybe that would do the trick.

    Thanks

    Rob

    Sony A390 with kit lens


     
  2. Mach0

    Mach0 TPF Supporters Supporting Member

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  3. o hey tyler

    o hey tyler Been spending a lot of time on here!

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    It may have been this photo that you saw, I might have posted it in a prime lens thread because I am huge fan of prime lenses.

    [​IMG]

    I shot this at f/3.5, but I did so with an 85mm focal length on a full frame camera, which gives me more reduced DoF than on an APS-C camera w/ the same settings, focal length, and subject framing.

    The longer your focal length, the shorter the DoF at f/3.5... So for example, if you're shooting at 18mm @ f/3.5 your DoF is going to be 1.48 meters. If you're shooting at 85mm @ f/3.5 your DoF will be .05 meters.

    As you can see, there's a drastic difference that focal length will make at a constant aperture. So the least DoF you can get with your current setup is 55mm on your kit lens at f/5.6 which would be .15 meters (without knowing the close focus distance of the lens).
     
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  4. Josh66

    Josh66 Been spending a lot of time on here!

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    Just make sure the background is far from the subject (and you are close) and it should be doable.
     
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  5. robbyrob

    robbyrob TPF Noob!

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    thanks you all for your help with this.. Mach0 and o hey tyler thanks for the technical aspect. It helped me learn and understand DOF in relation to the subject and lens. O|||||||O thanks for the layman's terms. Sometimes I need to hear the "for dummies" version to understand the technical. in all I took this picture which i think put what all you said into perspective. I wasn't worried about composition or didn't even do any post production. That's a whole other war going on in my head. Just trying to do it one technique at a time and actually have fun taking pictures. Well here the pic I took which had the effect I wanted and didn't even need to get another lens to do it..

    thanks guys

    [​IMG]
     
  6. Crollo

    Crollo TPF Noob!

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    That looks pretty good. Just get a farther background and stick a human face in the middle [or wherever fits compositionally] and you're golden. :)
     
  7. rickztahone

    rickztahone TPF Noob!

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    Just so that you know, the technical term is bokeh. As you noticed, the LARGER the aperture, the better the bokeh. As o hey tyler explained, this has to do with DOF (depth of field). The closer the subject is to the lens the easier it is to get bokeh but a lot of it depends on the lens as well.

    The following photograph depicts bokeh at f4. The lens has a 2.8 potential but you can see that the bokeh is still there. some lens just have a harder time with the DOF.
    [​IMG]
    Griffith Plant by rickztahone, on Flickr
     
    Last edited: Mar 1, 2012
  8. MTVision

    MTVision Been spending a lot of time on here!

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    You get a shallow depth of field from large apertures not small.
     
  9. rickztahone

    rickztahone TPF Noob!

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    lol, yeah, sry that's what i meant. It still confuses me at times.

    OP, LARGER aperture's for bokeh

    (FIXED)
     
  10. DiskoJoe

    DiskoJoe Been spending a lot of time on here!

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    Go get you a Minolta 50mm f1.7

    They are pretty cheap and give you almost a full range of aperture.
     
  11. rickztahone

    rickztahone TPF Noob!

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    also, Rob, what specific lens are you shooting with?
     
  12. rickztahone

    rickztahone TPF Noob!

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    This.

    I was actually going to get the 50 1.7 but i think i might go with the Sigma 50 1.4 instead. But i have heard nothing but good things about the 50 1.7
     

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