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Thread: How to blur out the Background? NEED HELP!

  1. #1
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    Default How to blur out the Background? NEED HELP!

    im using Sony Vegas 7 and the Sony DSC h5. I trying music video production, an in most videos they do an effect where the person is veiwable(you can see the person) but the background is blur. I want to know how do I do that....is it done in sony vegas or Its usually done with the camera?

    Thanks!

  2. #2

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    It would normally be done in camera. The effect is known as depth-of-field and is achieved by using a larger aperture (Iris). It is easier with longer focal lengths.
    There are techniques to do it digitally, although I'm guessing you would need something like After Effects to achieve it. Not a Vegas user, so I don't know about that, but it is easier to do in camera.

  3. #3
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    You COULD achieve an approximation in Vegas Pro.

    Place a copy of the same video on two tracks synced up.
    Use Bezier masks to draw around the subject in the foreground on the top track.
    Use a defocus or blur effect on the lower track.

    However,
    This will quickly become very tediaous as you have to redraw/move the mask for every frame (assuming the subject is moving)
    It is not really a DOF effect as with real DOF objects nearer the camera are less out of focus than those futher away.

    You won't achieve much in the way of DOF with an H5 as one of the critical factors in creating large DOF is the sensor size. The sensor on your camera is onlu 1/2.5 in wheras "proper" cameras shoot on (have a "sensor" size of 35mm)

    There is a market in "35mm adapters". Whether one is available which will fit your camera I don't know, but even if it is it will cost considerably more than your camera.
    Tim

  4. #4

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    Quote Originally Posted by TimStannard View Post

    You won't achieve much in the way of DOF with an H5 as one of the critical factors in creating large DOF is the sensor size. The sensor on your camera is onlu 1/2.5 in wheras "proper" cameras shoot on (have a "sensor" size of 35mm)

    .
    It is interesting the differerence in terminology between still and video shooting!
    Depth-of-field refers to the amount of an image that is in acceptable focus, therefore to achieve this effect you want a small depth-of-field!
    Sensor size has a bearing on it inasmuch as where a large depth of field is required, it is easier to achieve with a smaller sensor and conversely a shallower DOF is easier to get with a larger sensor.
    However, sensor size is not the only variable. Distance to the subject and focal length also have a bearing. Longer focal lengths (i.e. zoom in) will help.

    Another way that will help is to use manual focus (if available) and focus on a point closer than your subject, keeping the subject just within that acceptable focus. That will help to throw the background OOF.

  5. #5

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    Use loooong zooms (and a good tripod) and higher shutter speeds, that normally sorts it out, if iris is auto

  6. #6

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    Best done in camera. But, there is an FX for this in NewBlue FX 2 which works quite well.

  7. #7
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    Im pretty new to photoghraphy and cameras..so some the things you guys talking about I have no idea what your talkin about like the DOF and the Sensor. Can someone explain them both?

    And Timstannard you mentioned the 35mm adapter, Ive been looking for an adapter that will fit my sony dsc h5. Suppose I brought a canon adapter would I be able to connect it to a sony camera and use it? and which one would work best with mine?

    To Archie, that NewBlue Fx is this a Plugin effect that I can use in Sony Vegas?
    Last edited by DTMG; 10-27-2009 at 06:11 PM.

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    Sorry, DOF is simply an abbreviation for depth of field (explained by IanA)
    By "sensor" I was trying to come up with a term that described the area onto which the lens projects an image. In Digital camcorders/cameras, these are, indeed electronic sensors (CCDs or CMOS might be abbreviations you've seen in adverts/specifications). In traditional photography, this is the actual film or frame.

    Can't help with 35mm adapters I'm afraid. I just know they exist and have had the principle explaine dto me (on this very forum)

    And finally, on Archies behalf, YES NewBlueFX do a good selection of plugins which work with Vegas (at a reasonable cost as well). Archie is a bit of a fan.
    Tim

  9. #9

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    Quote Originally Posted by DTMG View Post
    Im pretty new to photoghraphy and cameras..so some the things you guys talking about I have no idea what your talkin about like the DOF and the Sensor. Can someone explain them both?
    Firstly, you have jumped into one of the most confusing areas of photography there is to understand. But once you have nailed it, you will be genuinely liberated from the obstacles that the majority of no-hopers can't be bothered to hack or crack.

    Secondly, you really are going to have to realise that video cameras are a very limited tool in capturing all that you wish. They are truly hopeless things, when it comes to wanting more. But with a little coxing and being realistic as to what they CAN dish up, you wont be too disappointed.

    Thirdly, you are going to need to take your time and read and read and read. You have much to learn. Pressing that red button IS the simplest, and beguiling things of all the things to do. Understanding more of what you can do with your video camera is a 1000 paces away from that finger press.

    OK - Here is a link intro into DoF = Depth of Field. What you are after is to be able to create "Shallow" DoF. This in turn gives you that blurred background. And guess what - if you DID have somebody near to the camera, and slightly to the side they TOO would be blurred. Here's that link:

    Understanding Depth of Field in Photography

    PLEASE Note the comment of using ZOOMs!

    OK, DoF adaptors are neither SONY nor Canon nor Panasonic (I'm almost sure they don't supply off-the-shelf adaptors like a wide-angle adpator!!) nor . .whatever . . these "bolt-on" 3rd party machines sit directly in front of your camera and dictate what your video camera sees on the backside of the adaptor. Your VidCam has been concerted to a "dumb" gadget simply recording what the DoF adaptor shows it. Now, and here is the clever bit, on the front end of these machines we can snap, or twist on, a humongous selection of still camera lenses that were meant for 35mm stills cameras. See that? 35mm format? that's like 3.5cms in each direction! THAT'S BIG!! What is the size of your sensor in your Video camera? That's your first task - go find out just WHAT the size of your sensor is. Think about, and then slump down in disappear. It will be tiny. And what YOU are wanting to do - along with me too - is get as best a blurry background as poss.

    So that's the DoF Adaptor "skidded" over. Read up more on these puppies and see the prices too.

    My approach is to keep the aperture open wide; get as close to the SUBJECT as feasible and control the light coming in ( IRIS is wide open) with ND filters both IN-camera and added to my Matt Box. You can control light coming in with the shutter seed but I find I start introducing movement abnormalities/artifacts.
    Last edited by Grazie; 10-27-2009 at 10:02 PM.

  10. #10

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    Quote Originally Posted by Grazie View Post
    a humongous selection of still camera lenses that were meant for 35mm stills cameras. See that? 35mm format? that's like 3.5cms in each direction! THAT'S BIG!!.
    35mm film is actually 36mm x 24mm! Go figure!!

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