1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

The F factor

Discussion in 'Camcorders, Action Cams & Video Editing Forum' started by zOOm BooM, Jan 11, 2003.

  1. zOOm BooM

    zOOm BooM
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Hi there, I hope you can help me.

    Two questions:
    1 - I have a JVC GR-DV2000 which has a F1.8 lens. It's performance in low light is not the best since it does not have the "night shot" features of some other cameras.

    I'm looking to upgrade to JVC GR-DV3000 and noticed that it has a F1.2 lens. JVC claims this gives the camera better "Low light" capability as a F1.2 lens will let in more light. I accept this however.... I have been checking and here's one comment that concerns me:

    "Put simply, a larger aperture (smaller f-number, eg. f/2) has a shallow depth of field, anything behind or in front of the main focus point will appear blurred. A smaller aperture (larger f-number, eg. f/11) has a greater depth of field, objects within a certain range behind or in front of the main focus point will also appear sharp."

    The GR-DV3000 seems to have the largest aperture of any digital camcorder on the market at this time.

    Can anyone please explain to me how much of an effect this will have on day-to-day usage of the camera?

    2 - The JVC GR-DV3000 is supposed to have a night shooting mode JVC calls "NightAlive". The only place I have seen this mentioned is in JVC's promotional material. No review I have seen has ever included this. Does this work and how effective is it? Also, if it is really effective and really good, then why the need for a F1.2 lens?

    Thanks.
     
  2. umpf75

    umpf75
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Hi zOOm BooM

    Perhaps I can call upon my SLR camera knowledge to help explain part of your question.

    To get the correct exposure the camera uses the aperture ( f-stop) and the shutter speed together.

    Open the aperture up by one stop and you can increase the shutter speed to get the right exposure again. So why do this? Well you are right about the depth of field. So if you have total manual control then this is what you can play with. For example. A shot of a person with a back ground which you can "force" out of focus using the aperture is often used by photographers so the viewer focuses on the person. To get the exposure right just increase the shutter spead.

    So during general day to day exposure on automatic mode what happens? Well this depends on the camera and the programming of the auto exposure mode. certainly for still (SLR ) phtography a general is that inorder to capture a picture and not have camera shake then you shutter speed will need to be as quick as the lense is long eg 100m lens 1/125 of a second.

    Most cameras are programmed to use 1/125 or 1/250sec shutter speeds and alter the aperture. this gets rid of camera shake on the whole. so if the light level drops the camera opens up the aperture until it cannot open it any more. If it still needs more light to get the exposure right then it starts to slow the shutter down.

    So this rather long waffle means in general conditions it makes no difference at all - unless you want to control the depth of field.


    It really comes into effect as the light fades and then the camera can keep the shutter speed higher for longer and avoid camera shake. In video terms that means crisper frames.

    Hope that helps
     
  3. umpf75

    umpf75
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Part two of your question.... Night Alive.

    What digital can do over normal film is electronically manipulate the image. Basically turn the bightness up as you would on the TV. If you have no light then there is nothing to turn up. If you have an f1.2 lens then you have more chance of capturing light in the first place to then be able to turn the brightness up on.

    So the JVC gives itself an advantage by caputing more light to start with which gives a better picture to then be able to adjust to give you Night Alive.

    How good it is I don't know specifically for the JVC

    How ever I have just gone through this dilemma with chosing my first camcorder and decided that there were several other factors against the JVC.

    1) Tape is bottom loading. If you are recording in low light using a tripod you will have to take the camera off to change tape.
    2) It has no mic socket and that to me was not good. Esp if you want to use a remote mic.

    So hope this part two helps
     
  4. zOOm BooM

    zOOm BooM
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Thanks umpf75, that was very helpful. I think I will go for this now. I do not have a need for an external mic but I did notice that the JVC has a "zoom mic" which is supposed to pick up the voice of the subject that you zoom in to.

    Thanks again.
     

Share This Page

Loading...