aperture question

Discussion in 'Photography Beginners' Forum' started by swmocity, Jul 23, 2009.

  1. swmocity

    swmocity TPF Noob!

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    and yes i have looked it up already...ive seen some full body picture where the background is completely out of focus...to get the background out of focus u would have to use 2.8...2.2...i understand that...but what i dont understand is how is it possible to use a low fstop but still manage to get the full body in focus and the background blurred...dosent a low fstop decrease the DOF?
     
  2. Bitter Jeweler

    Bitter Jeweler Been spending a lot of time on here!

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    DOF changes with your distance from the focused subject.
     
  3. Markw

    Markw No longer a newbie, moving up!

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    Care to elaborate?

    Mark
     
  4. Sachphotography

    Sachphotography TPF Noob!

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    Well. Um...hmmm.. I am confused. Why would you want to use a low f stop but have a wide DOF they slightly contradict each other. What are you trying to do? The only way to use a lens at a low F stop would be to position you self further away from the object in which you are taking a picture. Does that help? If you are not further away, your DOF will be shallow
     
  5. swmocity

    swmocity TPF Noob!

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    i just happeen to look at the picture on the net and it kind of confused me...it was a full body picture of two people, like a downtown street location...but the background was all the way out of focus but the people werent...to get the background completely wouldnt u have to use a low fstop? which decreases the DOF...but somehow the subjects entire body was still in focus
     
  6. swmocity

    swmocity TPF Noob!

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    or maybe it was the distance between the subject and the background and not so much of the fstop...i cant find the link to the picture
     
  7. Markw

    Markw No longer a newbie, moving up!

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    That sounds like it could be it. The low F-stop does give you a shallow DOF, but that DOF is still wherever you focus, so if the photographer focused on the people, they would be in focus, but anything behind them and infront of them would be out of focus. The further in the foreground and further in the background you go, the more out of focus the image will become with any F-stop. The severity of the blurred back and foreground is just dramatically increased with a low F-stop.

    Hope that makes sense.
    Mark
     
  8. Dao

    Dao No longer a newbie, moving up!

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    Aperture is one of the factor when calculating DoF. There are other factors controlling the DoF.


    Go here
    Online Depth of Field Calculator

    While you are there, choose the camera and play with the settings.

    Now, set the Focal Length, F-stop and the subject distance.
    Change one settings at a time. i.e., if you want to know the effect of aperture on DoF, just change the Aperture.

    Pay attention to the Depth of Field - Near limit and Far limit.

    Anything within the range of Near limit and Far limit are going to be in focus. As you will see, you can make it so that the distance between Near limit and Far limit (DoF) is couple feet long (even if the Aperture is wide). In that case, both person should be in focus.
     
  9. Sachphotography

    Sachphotography TPF Noob!

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    Im lost.... sorry. I don't know what you are asking. Only thing I can think of would be the distance between the background and the people
    but that was already said.
     
  10. Markw

    Markw No longer a newbie, moving up!

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    That link was extremely informative (sp?). Helped alot with my understanding. Thanks.

    Mark
     
  11. swmocity

    swmocity TPF Noob!

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    yes one more question...so basically its like a "focus circle" i guess?...does the DOF start out in the middle then expands out in a circular pattern...hopes that make since...its kind of hard to explain lol
     
  12. swmocity

    swmocity TPF Noob!

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    thank you...this explains it all
     

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