focus and blurred background

This is a discussion on focus and blurred background within the Composition forums, part of the Photography Tips category; I'm trying to get that effect in a portrait where the face of the person is on focus, but the background is blurried, but I ...


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  1. #1

    Join Date
    Dec 2010
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    I'm trying to get that effect in a portrait where the face of the person is on focus, but the background is blurried, but I have some questions:

    1) to do it, I use the lowest f/ value (in my camera it's 2.8) and focus on the face. This way I should get a shallow depth of field. Is it the correct way to do it?
    2) I do it with manual focus, but can I achieve the same effect with autofocus (obviously having the camera focus on the person's face)?
    3) Is there a maximum distance that can lie between the camera and the person in the portrait?
    4) Is there a maximum distance that can lie between the person's face and the background?
    5) Can I get this effect while zooming? and if yes, is there a maximum distance?

    Thanks




  • #2
    Senior Member
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    PHOTO EDITING NOT OK
    Quote Originally Posted by alphabravo View Post
    I'm trying to get that effect in a portrait where the face of the person is on focus, but the background is blurried, but I have some questions:

    1) to do it, I use the lowest f/ value (in my camera it's 2.8) and focus on the face. This way I should get a shallow depth of field. Is it the correct way to do it?
    2) I do it with manual focus, but can I achieve the same effect with autofocus (obviously having the camera focus on the person's face)?
    3) Is there a maximum distance that can lie between the camera and the person in the portrait?
    4) Is there a maximum distance that can lie between the person's face and the background?
    5) Can I get this effect while zooming? and if yes, is there a maximum distance?

    Thanks
    I can help with a few and other folk might give you the more technical answers

    1. Yes,basically that's the way to do it-f2.8 will give you the least dof but this will also apply to the face you have in focus so: if you have the eyes in focus at f2.8 then the ears may not be and so on. You can alter what you have by increasing the f-number(narrowing the aperture) until you strike the balance that you like best.

    2.Yes, manual or auto will give the same dof for a given lens

    3.

    4.Try not to have the subject too close as this will cause harsh shadows if you shoot with flash

    5.If you mean closing in on a subject by using the lens and not you physically moving, then the answer is still yes.

    Remember that each lens,for a given f-number will give a different dof and the best way for you to get to learn what that means just take lots and lots of shots of the same thing but each at a different aperture.Make notes as you go and then you'll have some reference to interpret what you see on screen.Afterall a few ones and zeros don't cost anything...

    Karin


    Taking photos that please me, but if you like them too then it's a bonus!

  • #3

    Join Date
    Dec 2010
    Posts
    12
    thanks,

    you made it much clearer





    Quote Originally Posted by Kiasmum View Post
    Quote Originally Posted by alphabravo View Post
    I'm trying to get that effect in a portrait where the face of the person is on focus, but the background is blurried, but I have some questions:

    1) to do it, I use the lowest f/ value (in my camera it's 2.8) and focus on the face. This way I should get a shallow depth of field. Is it the correct way to do it?
    2) I do it with manual focus, but can I achieve the same effect with autofocus (obviously having the camera focus on the person's face)?
    3) Is there a maximum distance that can lie between the camera and the person in the portrait?
    4) Is there a maximum distance that can lie between the person's face and the background?
    5) Can I get this effect while zooming? and if yes, is there a maximum distance?

    Thanks
    I can help with a few and other folk might give you the more technical answers

    1. Yes,basically that's the way to do it-f2.8 will give you the least dof but this will also apply to the face you have in focus so: if you have the eyes in focus at f2.8 then the ears may not be and so on. You can alter what you have by increasing the f-number(narrowing the aperture) until you strike the balance that you like best.

    2.Yes, manual or auto will give the same dof for a given lens

    3.

    4.Try not to have the subject too close as this will cause harsh shadows if you shoot with flash

    5.If you mean closing in on a subject by using the lens and not you physically moving, then the answer is still yes.

    Remember that each lens,for a given f-number will give a different dof and the best way for you to get to learn what that means just take lots and lots of shots of the same thing but each at a different aperture.Make notes as you go and then you'll have some reference to interpret what you see on screen.Afterall a few ones and zeros don't cost anything...

  • #4

    Join Date
    Apr 2011
    Posts
    18
    PHOTO EDITING NOT OK
    DoF is based on aperture, distances between camera, target and backround and also of focal length.
    Larger the aperture, more DoF
    You should have camera closer to target than is distance between target and background.
    If distance between camera and target remains the same, the longer focal length provides more DoF

  • #5

    Join Date
    Jul 2011
    Posts
    1
    QUOTE
    I'm trying to get that effect in a portrait where the face of the person is on focus, but the background is blurried, but I have some questions:

    1) to do it, I use the lowest f/ value (in my camera it's 2.8) and focus on the face. This way I should get a shallow depth of field. Is it the correct way to do it?
    2) I do it with manual focus, but can I achieve the same effect with autofocus (obviously having the camera focus on the person's face)?
    3) Is there a maximum distance that can lie between the camera and the person in the portrait?
    4) Is there a maximum distance that can lie between the person's face and the background?
    5) Can I get this effect while zooming? and if yes, is there a maximum distance?

    Thanks
    Alphabravo,

    Good questions they all are, and I'll try and answer them as clearly as I can.

    You are right that using the smallest possible f-number creates the lowest possible depth of field (i.e. the smallest possible area that is in focus.) However, other things also play a roll, for instance the focal length of the lens, the distance from the subject and the size of your sensor.

    In general, the depth of field is greater for a shorter lens, for a longer distance from the subject and for a smaller sensor.

    As all of these things play a role, it is difficult to give a definitive answer about how to create the exact amount of depth of field you need.

    There are three ways of getting around this. First, many cameras now have a depth of field preview button, which closes down the f-stop and shows you a preview of what can be expected. (The DOF preview button will normally have no effect if pressed when you have the smallest f-number selected, as what you see is already what you will get.) Secondly, you can take a picture on a digital camera and review the result on the back of the camera and finally, you can use a depth of field calculator if your needs are very exact.

    I have posted a link to a site that does automatic depth of field calculations below, and it really is a great resource. The other two sites are also handy in learning more about the general concept of depth of field and I would recommend reading widely on the subject, as it really is the key to starting to separate your pictures from the mediocre.

    Depth of Field Calculator
    Basic Photography
    Wikipedia - Depth of Field

    I hope that helps.

  • #6
    Junior Member
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    Aug 2017
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    PHOTO EDITING OK
    is using a prime lens would help with this?

  • #7
    Member
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    Apr 2017
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    PHOTO EDITING OK
    You could also get a similar effect in a photo editing software by applying blur to a selected background area on an image you have already taken.


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