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Thread: OOF blur/bokeh quality when focusing to infinity

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    Default OOF blur/bokeh quality when focusing to infinity

    I had a good read on this forum regarding this OOF blur relating to when a lens focuses to infinity , but i jus can't seem to be able to find the thread now.

    can some1 help me?

    eg, when the lens focus to infinity on the subject, can i expect nice bokeh quality from the lens or will be background be simply Out of Focus blur?
    Stirring up emotions with pics - cyliew

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    Bokeh depends on lens characteristics and image composition. Focusing to infinity, etc, has nothing to do with bokeh.
    Alpha

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    Default Re: OOF blur/bokeh quality when focusing to infinity

    i hv uploaded 2 photos here....
    same shutter speed and aperature value, jus different focusing distance

    pic 1, focusin not to infinity.

    DSC_1371 by ijnek, on Flickr

    pic 2, focusing distance at infinity

    Focus distance infinity by ijnek, on Flickr

    look at the same area, the left leg the mouse behind it.
    in pic 1, the mouse clearly is more blur compare to the 1 in pic 2...

    probably my question should hv been DOF when focusing to infinity...
    Last edited by ijnek; 7th January 2013 at 09:24 PM.
    Stirring up emotions with pics - cyliew

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    Moderator Octarine's Avatar
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    Default Re: OOF blur/bokeh quality when focusing to infinity

    Do read up about the basics of Depth of Field and the contributing factors. Pay attention to focal length - Use the many online calculators and compare the results.
    EOS

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    Default Re: OOF blur/bokeh quality when focusing to infinity

    distance to subject & distance from subject to background plays a part in determining your oof blur as well

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    Default Re: OOF blur/bokeh quality when focusing to infinity

    That right! Same shutter speed and aperture value also doesn't give you the same exposure when u zoom in...

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    Default Re: OOF blur/bokeh quality when focusing to infinity

    thx...i found the point tat i'm tryin to confirm.

    Depth Of Field and camera to object distance - The second control you can employ to control depth of field is the distance between the camera and the object you are shooting. The greater this distance is the more depth of field you will have.

    will probably confirm y i need a 85mm etc for a full body portrait instead of using a 50mm
    Stirring up emotions with pics - cyliew

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    Default Re: OOF blur/bokeh quality when focusing to infinity

    Quote Originally Posted by ijnek View Post
    pic 2, focusing distance at infinity

    Focus distance infinity by ijnek, on Flickr

    look at the same area, the left leg the mouse behind it.
    in pic 1, the mouse clearly is more blur compare to the 1 in pic 2...

    probably my question should hv been DOF when focusing to infinity...
    You sure the 2nd pic is focused to infinity?

    From the EXIF of Pic 2
    Focus Distance 2.51 m

    Doesn't look like focused to infinity to me. Actually it shows in your pic... how can the lens be focused to infinity if the things behind the toy are blur?


    Quote Originally Posted by ijnek View Post
    thx...i found the point tat i'm tryin to confirm.

    Depth Of Field and camera to object distance - The second control you can employ to control depth of field is the distance between the camera and the object you are shooting. The greater this distance is the more depth of field you will have.

    will probably confirm y i need a 85mm etc for a full body portrait instead of using a 50mm
    DOF is affected by 4 things only:

    1. Focus distance: not necessarily subject to camera distance, the distance to camera from the point where the lens is focused on.
    2. Aperture used
    3. Focal length
    4. Circle of confusion: Explanation here

    Quote Originally Posted by ijnek View Post
    I had a good read on this forum regarding this OOF blur relating to when a lens focuses to infinity , but i jus can't seem to be able to find the thread now.

    can some1 help me?

    eg, when the lens focus to infinity on the subject, can i expect nice bokeh quality from the lens or will be background be simply Out of Focus blur?
    When you really focus to infinity, there will be NO background blur. Because everything far away will look sharp to you. But you might get some foreground blur, if the foreground is too close to you.

    This picture is shot at F3.5 at around 45mm focal length, focused to infinity. Notice how everything looks to be in focus. Why I chose such a large aperture? Simply because I did not bring my tripod with me. So I have to up my ISO and open up my aperture to get a fairly fast shutter speed. And at the same time, I know that since the elements in my picture are all in infinity range for the lens, I can get it all sharp at F3.5. Even if I used F2.8, the picture would have been reasonably sharp.
    Last edited by daredevil123; 8th January 2013 at 08:18 AM.

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    Default Re: OOF blur/bokeh quality when focusing to infinity

    thx dd123, i'm quite sure it's at inifinity as i'm using the 50mm and i checked the focusin shows it's at infinity.
    if i remember correctly, the marking shows it's at inifinity which i checked b4 snappin the pic.

    also, ur pic helped me a lot to understand this better.

    at this point, i'm quite sure that when focus to infinity, the back ground will b sharp and bokeh effect will hardly b there.
    which is y I should hv a longer focal length length if i wan to do a full body portrait pic with bokeh effect.
    the 50mm would not be suitable as i would need to be further away from subject and the distance to subject might be at infinity....

    thx and do correct me if i'm wrong again
    Last edited by ijnek; 8th January 2013 at 10:14 AM.
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    Moderator daredevil123's Avatar
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    Quote Originally Posted by ijnek View Post
    thx dd123, i'm quite sure it's at inifinity as i'm using the 50mm and i checked the focusin shows it's at infinity.
    if i remember correctly, the marking shows it's at inifinity which i checked b4 snappin the pic.

    also, ur pic helped me a lot to understand this better.

    at this point, i'm quite sure that when focus to infinity, the back ground will b sharp and bokeh effect will hardly b there.
    which is y I should hv a longer focal length length if i wan to do a full body portrait pic with bokeh effect.
    the 50mm would not be suitable as i would need to be further away from subject and the distance to subject might be at infinity....

    thx and do correct me if i'm wrong again
    The focus scale markings is iffy because it is not linear. It might seem you are at infinity mark but slightly off only you will be at 3m or so... i am very sure your lens at pic 2 is not at infinity.

    You should try at least 135mm or even something like 180 or 200mm if you want good background blur for full body.
    Last edited by daredevil123; 8th January 2013 at 10:19 AM.

  11. #11

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    Quote Originally Posted by ijnek View Post
    thx dd123, i'm quite sure it's at inifinity as i'm using the 50mm and i checked the focusin shows it's at infinity.
    if i remember correctly, the marking shows it's at inifinity which i checked b4 snappin the pic.

    also, ur pic helped me a lot to understand this better.

    at this point, i'm quite sure that when focus to infinity, the back ground will b sharp and bokeh effect will hardly b there.
    which is y I should hv a longer focal length length if i wan to do a full body portrait pic with bokeh effect.
    the 50mm would not be suitable as i would need to be further away from subject and the distance to subject might be at infinity....

    thx and do correct me if i'm wrong again
    Uhm. There is no "bokeh effect". Next, if you want to do a full-body portrait and want to blur the background, then shoot at a large aperture (such as f/2.8) and focus on the subject and make sure there is good distance to the background (a few meters).

    I don't know why you are even bringing infinity focus into this. Also, if the subject distance is at infinity... do you know what infinity means? ;-)
    Alpha

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    Default Re: OOF blur/bokeh quality when focusing to infinity

    thx dd123.

    that was 1 point i was tryin to tell another guy...cos the talk was if he has a 50mm, can't he just take lots of steps back to snap a full body shot with bokeh effect.it's a a dx body, so the view is narrower and he need more distance for a full body shot.

    i was tryin to tell him once his lens focus to infinity distance, his background blur would not be as pretty etc....
    Stirring up emotions with pics - cyliew

  13. #13

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    Quote Originally Posted by ijnek View Post
    thx dd123.

    that was 1 point i was tryin to tell another guy...cos the talk was if he has a 50mm, can't he just take lots of steps back to snap a full body shot with bokeh effect.it's a a dx body, so the view is narrower and he need more distance for a full body shot.

    i was tryin to tell him once his lens focus to infinity distance, his background blur would not be as pretty etc....
    "Pretty" or "not pretty" background blur has nothing to do with focusing on infinity. Not sure why you think there's a link.
    Alpha

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    Default Re: OOF blur/bokeh quality when focusing to infinity

    Quote Originally Posted by ijnek View Post
    thx dd123.

    that was 1 point i was tryin to tell another guy...cos the talk was if he has a 50mm, can't he just take lots of steps back to snap a full body shot with bokeh effect.it's a a dx body, so the view is narrower and he need more distance for a full body shot.

    i was tryin to tell him once his lens focus to infinity distance, his background blur would not be as pretty etc....
    The bokeh thingy that you are talking about only got to do with the aperture AND the distance of the subject to the background. Got nothing to do with focusing... The larger the distance your subject to the background, the more OOF you will get, the larger the aperture, the more "bokehish" it gets.

    Focusing to infinity only means that from x point on wards to the "seeable" infinity everything is sharp. Imo, it's more or less related to hyperfocal distance.
    Too many great equipments but too little quality photos. [My Flickr] | [My Blog]

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    Default Re: OOF blur/bokeh quality when focusing to infinity

    hmmm...

    pls pardon my ignorance.

    with what dd123 mention, when i focus to infinity, there will be no background blur.

    every lens has a focusing distance range before it goes to infinity.
    Stirring up emotions with pics - cyliew

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    Default Re: OOF blur/bokeh quality when focusing to infinity

    I suggest taking a look at Online Depth of Field Calculator

    So, you know when you will have blurish background/foreground and when not...
    Too many great equipments but too little quality photos. [My Flickr] | [My Blog]

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    Default Re: OOF blur/bokeh quality when focusing to infinity

    Quote Originally Posted by ijnek View Post
    hmmm...

    pls pardon my ignorance.

    with what dd123 mention, when i focus to infinity, there will be no background blur.

    every lens has a focusing distance range before it goes to infinity.
    This depends on the focal length of the lens, the aperature and also the focus distance. If you get it right you will get half the focus distance till infinity in focus or what is called the hyper-focal distance.
    Shoot First, Ask Questions Later...
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    Default Re: OOF blur/bokeh quality when focusing to infinity

    thx, i checked that and i'm pretty sure abt focusing distance with related DOF.
    i changed the subject distance value to checked the Total Depth of Field.

    my concern is every lens has a focusing distance range before it reaches infinity....
    Stirring up emotions with pics - cyliew

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    Default Re: OOF blur/bokeh quality when focusing to infinity

    Quote Originally Posted by ijnek View Post
    thx, i checked that and i'm pretty sure abt focusing distance with related DOF.
    i changed the subject distance value to checked the Total Depth of Field.

    my concern is every lens has a focusing distance range before it reaches infinity....
    What is this concern that you are concerned about?

    So long you know the focal length and the aperture, you can easily know where is the point that it will start focusing to infinity.
    Last edited by SkyStrike; 8th January 2013 at 11:12 AM.
    Too many great equipments but too little quality photos. [My Flickr] | [My Blog]

  20. #20

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    Quote Originally Posted by ijnek View Post

    my concern is every lens has a focusing distance range before it reaches infinity....
    What about it? Lol. Of course it has a range. If not discrete extremes?
    hi

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