Results 1 to 15 of 15

Thread: newbie need help about lens n crop factor

  1. #1

    Default newbie need help about lens n crop factor

    hi there! im using canon 1000D and tried to use fisheye lens but was wondering why i cant get full 180 degrees of angle..is it due to the crop factor of my sensor or what??

  2. #2
    Senior Member zac08's Avatar
    Join Date
    Feb 2005
    Location
    East
    Posts
    11,755

    Default Re: newbie need help about lens n crop factor

    Quote Originally Posted by anyone View Post
    hi there! im using canon 1000D and tried to use fisheye lens but was wondering why i cant get full 180 degrees of angle..is it due to the crop factor of my sensor or what??
    Yes... the 1.6x crop will reduce your field of view.
    Michael Lim
    My Flickr Site

  3. #3

    Default Re: newbie need help about lens n crop factor

    how many mm is ur fisheye? for 16mm fisheyes, you normally wont notice much on a 1.6crop sensor.
    try using a 10 or 8mm fisheye
    Last edited by wdEvA; 6th January 2009 at 04:11 PM.

  4. #4

    Default Re: newbie need help about lens n crop factor

    Quote Originally Posted by anyone View Post
    hi there! im using canon 1000D and tried to use fisheye lens but was wondering why i cant get full 180 degrees of angle..is it due to the crop factor of my sensor or what??
    I just helped some friends buy the Canon Digital Rebel XSi. When shooting with a camera that is not full frame, like in your case, multiply the focal length by 1.6. So if you are shooting with a 15mm fixed lens your camera produces and image that is at a focal length of 24mm. 15mm x 1.6 = 24mm I hope this helps you.

  5. #5
    Moderator ortega's Avatar
    Join Date
    Nov 2004
    Location
    Singapore, Singapore, Singapor
    Posts
    23,686
    Blog Entries
    7

    Default Re: newbie need help about lens n crop factor

    google it for more [crop factor]

    or click this if you need spoon feeding

    http://www.kenrockwell.com/tech/crop-factor.htm

  6. #6
    Senior Member
    Join Date
    Jun 2003
    Location
    Singapore, Bedok
    Posts
    1,785

    Default Re: newbie need help about lens n crop factor

    Quote Originally Posted by jvanhatten View Post
    I just helped some friends buy the Canon Digital Rebel XSi. When shooting with a camera that is not full frame, like in your case, multiply the focal length by 1.6. So if you are shooting with a 15mm fixed lens your camera produces and image that is at a focal length of 24mm. 15mm x 1.6 = 24mm I hope this helps you.
    The smaller sensor does crop the full image, but the 1.6x math does not apply to fisheyes, only linear lenses. Eg a 10mm linear lens on a 1.6x gives a 16mm linear viewpoint (=16mm on FF), but a 10mm fisheye does not give a 16mm fisheye viewpoint: it gives a cropped 10mm fisheye viewpoint. A full-image 16mm fisheye still gives a 180 degrees diagonal viewpoint. A fisheye designed to give 180 degrees diagonal viewpoint will do so for it's intended image(sensor) size, independent of its actual focal length.
    Last edited by ST1100; 6th January 2009 at 05:10 PM.

  7. #7
    Member
    Join Date
    May 2004
    Location
    Thomson Road
    Posts
    67

    Default Re: newbie need help about lens n crop factor

    interestingly, how do u measure the view angle in an image?
    I own Nikon D90. My primary camera comes with Whatsapp.

  8. #8
    Senior Member
    Join Date
    Jun 2003
    Location
    Singapore, Bedok
    Posts
    1,785

    Default Re: newbie need help about lens n crop factor

    Quote Originally Posted by ch130176 View Post
    interestingly, how do u measure the view angle in an image?
    The lens will come with specs: horizontal view angle, vertical view angle, diagonal view angle.

    Imagine an isosceles triangle. The focal length of the lens is the height of the triangle, the width, height or diagonal of the sensor is the length of the base (36/24/43 for FF). The top angle of the triangle is the view angle. Hope this makes sense.

    Applies only to linear lenses.

  9. #9
    Senior Member jnet6's Avatar
    Join Date
    Apr 2004
    Location
    not here often anymore
    Posts
    8,169

    Default Re: newbie need help about lens n crop factor

    Quote Originally Posted by anyone View Post
    hi there! im using canon 1000D and tried to use fisheye lens but was wondering why i cant get full 180 degrees of angle..is it due to the crop factor of my sensor or what??
    what FE lens are you using?? one of the possible cause is that your fish eye is not for digital, try the tokina FE zoom 11-17, it should be better.

  10. #10

    Default Re: newbie need help about lens n crop factor

    Quote Originally Posted by jnet6 View Post
    what FE lens are you using?? one of the possible cause is that your fish eye is not for digital, try the tokina FE zoom 11-17, it should be better.
    No, that would have nothing to do with it. It doesn't matter if it's "for digital" or not. It all has to do with the FOV and his crop sensor.
    Alpha

  11. #11
    Senior Member jnet6's Avatar
    Join Date
    Apr 2004
    Location
    not here often anymore
    Posts
    8,169

    Default Re: newbie need help about lens n crop factor

    Quote Originally Posted by Rashkae View Post
    No, that would have nothing to do with it. It doesn't matter if it's "for digital" or not. It all has to do with the FOV and his crop sensor.
    even with full frame, not much lenses can do 180 deg of view.

  12. #12

    Default Re: newbie need help about lens n crop factor

    Quote Originally Posted by jnet6 View Post
    even with full frame, not much lenses can do 180 deg of view.
    On my old crop camera, my 7.5mm FE does almost 180 degrees. On FF, it actually turns into a FE circle in the center of the frame.
    Alpha

  13. #13
    Senior Member jnet6's Avatar
    Join Date
    Apr 2004
    Location
    not here often anymore
    Posts
    8,169

    Default Re: newbie need help about lens n crop factor

    Quote Originally Posted by Rashkae View Post
    On my old crop camera, my 7.5mm FE does almost 180 degrees. On FF, it actually turns into a FE circle in the center of the frame.
    Ya, firstly must let T/S understand type of lenses and crop factor or what type of camera body he has.

  14. #14
    Senior Member
    Join Date
    Jun 2003
    Location
    Singapore, Bedok
    Posts
    1,785

    Default Re: newbie need help about lens n crop factor

    Quote Originally Posted by jnet6 View Post
    even with full frame, not much lenses can do 180 deg of view.
    No rectilinear lens (non-fisheye) can do 180 degrees, *all* fisheyes can do 180 degrees diagonal FOV for the image size they were designed for.

  15. #15
    Senior Member jnet6's Avatar
    Join Date
    Apr 2004
    Location
    not here often anymore
    Posts
    8,169

    Default Re: newbie need help about lens n crop factor

    Quote Originally Posted by ST1100 View Post
    No rectilinear lens (non-fisheye) can do 180 degrees, *all* fisheyes can do 180 degrees diagonal FOV for the image size they were designed for.
    ok, thks!

Bookmarks

Posting Permissions

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