More questions

Discussion in 'Photography Beginners' Forum' started by Raeanne06, Mar 8, 2007.

  1. Raeanne06

    Raeanne06 TPF Noob!

    Joined:
    Mar 8, 2007
    Messages:
    4
    Likes Received:
    0
    Location:
    Ellsinore
    Can others edit my Photos:
    Photos OK to edit
    More "home study" book questions.


    1) Will a hand held camera with a 100mm lens, used with a shutter speed of 1/50 or faster produce a sharp image?

    2) After you focus a zoom lens, will it remain in focus as you change the focal length?

    3) Does perspective distortion result from the lens being too close to the subject, regardless of the focal length of the lens?
     
  2. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

    Joined:
    Dec 16, 2003
    Messages:
    33,817
    Likes Received:
    1,811
    Location:
    Edmonton
    Can others edit my Photos:
    Photos NOT OK to edit
    It feels like we are doing your homework for you. If these are questions in the back of the book...I'm sure the answers are in the book for you to learn.

    1) Probably not, the rule is that you would want a shutter speed of 1/focal length to get sharp shots

    2)Some do, some don't...the answer is probably no.

    3)I'm not sure :scratch:
     
  3. PetersCreek

    PetersCreek TPF Noob!

    Joined:
    Aug 5, 2005
    Messages:
    239
    Likes Received:
    4
    1) It depends. The general rule of thumb for handholding is to use a shutter speed of one over the focal length...in this case, 1/100th. I've violated the rule on occasion and gotten acceptably sharp pictures...but not as a rule. Add to that...there are other factors that can affect image sharpness.

    2) It depends on the lens but I don't care much. I'll always check focus after zooming.

    3) Theoretically, I suppose it does since all lenses translate our 3D vision to a 2D surface. More practically though, at the longer focal lengths, it becomes less noticeable. But it's not limited to cases of being too close to the subject, either. Very long focal lengths introduce their own "distortion" by compressing the perspective we normally visualize.
     
  4. fmw

    fmw No longer a newbie, moving up!

    Joined:
    Sep 30, 2006
    Messages:
    2,598
    Likes Received:
    137
    1. Not for me. If I want a sharp image with a 100mm lens, I'll go for 1/250 or higher. I don't have arms of granite, I'm afraid.

    2. The others are correct, some do some don't.

    3. Perspective distortion relates to both focal length and camera to subject distance. You can't separate them. In general longer lenses will forshorten perspective and wide angles will extend it but the effects could be reversed depending on the camera to subject distance. As an example, the reason we like the 100mm lenses you mentioned in the other post for portraits is that we can get far enough away from the subject to prevent perspective distortion and still get a frame filling image. Distance and focal length go hand in hand.
     
  5. EOS_JD

    EOS_JD TPF Noob!

    Joined:
    Feb 15, 2007
    Messages:
    1,698
    Likes Received:
    0
    Can others edit my Photos:
    Photos OK to edit
    As said above it depends how you shoot. If you can hold still prop yourself up against a wall or something you'll get a decent result. the 1/focal length is not really a written rule because everyone handholds differently. It's a guide.

    Try it and see how it works out.

    JD
     

Share This Page