Results 1 to 6 of 6

Thread: Fx Dx

  1. #1

    Join Date
    Apr 2011
    Location
    Cambridge, NZ
    Posts
    52
    Real Name
    Tom

    Fx Dx

    Hi,

    After some clarification here,

    I have a D7000, using an FX 35-70, If i use a DX 35mm prime would the picture size be the same as if i was using the fx lense at 35mm,

    Cheers

  2. #2
    rob marshall

    Re: Fx Dx

    Quote Originally Posted by Tuck View Post
    Hi,

    After some clarification here,

    I have a D7000, using an FX 35-70, If i use a DX 35mm prime would the picture size be the same as if i was using the fx lense at 35mm,

    Cheers
    Whatever lens you put on any camera it will produce the same image on that same camera provided the focal length is the same. It's the camera that makes the difference, not the lens.

  3. #3
    Black Pearl's Avatar
    Join Date
    Jan 2011
    Location
    Whitburn, Sunderland
    Posts
    2,397
    Real Name
    Robin

    Re: Fx Dx

    The number on all lenses is the actual focal length, it only has an apparent difference when you put the lens on a body with a smaller (crop) sensor.

    Therefor all 35mm lenses are 35mm and all will be the equivalent to 52.5mm on your D7000

    As a matter of interest which 35-70mm are you using......I hope the f2.8 one?

  4. #4

    Join Date
    Apr 2011
    Location
    Cambridge, NZ
    Posts
    52
    Real Name
    Tom

    Re: Fx Dx

    Thanks for your help,
    so the difference in the DX lense is that the image is taken from the whole diameter of the lense as opposed to a centre portion of the lense in the case of an FX,

    and so at the same listed focal length of each FX and DX lense the pictures will be the same.

    No its the 3.3-4.5, which i dont think is very good, was an old freebe from my dads days with film

  5. #5
    rob marshall

    Re: Fx Dx

    Quote Originally Posted by Tuck View Post
    so the difference in the DX lense is that the image is taken from the whole diameter of the lense as opposed to a centre portion of the lense in the case of an FX,
    No! The lens always projects the same image area. But in a DX camera (crop factor) the image overspills the smaller sensor, so you get what appears to be an enlarged image. But it isn't at all - it has just 'overspilled'. On a full frame camera the full image output from the lens gets onto the sensor because the sensor is physically larger. That is why cheap lenses on a full-frame camera often get distorted at the edges (the worst part of a lens), but on a crop factor camera it will 'crop out' those outer areas.

    Have a look at this http://www.cambridgeincolour.com/tut...ensor-size.htm
    Last edited by rob marshall; 18th June 2011 at 08:11 AM.

  6. #6
    Black Pearl's Avatar
    Join Date
    Jan 2011
    Location
    Whitburn, Sunderland
    Posts
    2,397
    Real Name
    Robin

    Re: Fx Dx

    so the difference in the DX lense is that the image is taken from the whole diameter of the lense as opposed to a centre portion of the lense in the case of an FX,
    Yes! A DX lens projects a smaller circle than a FX lens. In practice you tend to get a better edge-to-edge/corner-to-corner performance using a FX lens on a DX body as you are only using the centre of the circle which is the sharpest and most evenly illuminated. A DX lens will tend to be a little softer at the corners and have a little more light fall off as you are using all of its imaging circle - that said they are generally cheaper to buy, lighter and they all have the Silent Wave Motors so AF with the entry level bodies.

    As your D7000 is a DX body that has an internal AF drive you can pick and choose lenses at will to suit your end needs and budget.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •