2 Replies Latest reply on Aug 9, 2013 8:18 PM by MadManChan2000

    Helping LPC "build a more robust solution"...

    Señor Happy Level 1

      In this threadhttp://forums.adobe.com/message/3360946#3360946 – the Adobe staffer participating mentions in his reply that Lens Profile Creator "...would love to see chart images shot from a variety of camera position/orientation (roll & pan). It will help the software find a more robust solution."


      I can see by rummaging through any number of discussions related to individuals attempting to build their own camera-lens profiles that others are finding the directions included with the LPC software more than just a bit confusing. My own careful reading (several times over) has me interpretting the shoot instructions to place the target stationary then, with the camera also stationary (and centered on the target only taking up between 25% and 50% of the image frame):

      1) shoot dead-on, target in center;

      2) tilt camera up, shoot target with top edge aligned to the top, center edge of the viewfinder; then

      3) tilt camera down to shoot with the bottom edge of the target aligned to the bottom/center of the viewfinder;

      4) pan right to have the left edge and bottom edge of the target aligned to the lower left corner of the viewfinder;

      5) tilt up a bit to have the lens level but the target aligned with the left edge of the viewfinder;

      6) tilt up a bit more for the target's left and top edges aligned in that corner of the viewfinder; then

      7) pan left so that the target's upper and right edges align to the top and right of the viewfinder;

      8) down a bit for the lens almost level yet positioned so that the right edge of the target aligns with the right edge of one's viewfinder, and

      9) finally tilt down once more so that the last shot has the target's right and bottom edges align witht the lower right corner of the viewfinder.


      Now THAT would provide Pan and Roll and pretty much simulate real world conditions – where a photographer chooses a position to shoot their subject, then decides to pan up, down, right or left from that point in space for optimum composition. Right?


      If, as the staffer goes on to say "No need for the target to be perfectly vertical" then this manner of shooting for eventual processing within the software may be the way to go?




      One other thing I'm not finding an answer on:

      Even utilizing the smallest PDF graph included (printed to a US Letter size page), setting my 24mm-135mm lens to its shortest focal length (24mm) at its closest focusing point ("1.41' " or approximately 16 inches) the graph target fills my camera's viewfinder completely!


      > Aren't I supposed to do a series of 9 shots using my zoom lens'

        1) Shortest focal length, at its "minimum focus distance", "2x's its minimum focus distance" and "5x its minimum focus distance" or Infinity;

        2) then move on to the lens' longest focal length to do the same; and

        3) finally complete the series for an über profile by selecting a mid-way focal length to do the process one last time?


      * As I say above, setting my lens to its minimum focus distance at its shortest focal length that 'Letter' size graph fills the entire viewfinder.

      I'm not able to achieve a 25% - 50% subject ratio within my image frame.


      Should I just forget about shooting this series at the lens' "minimum focus distance" because of this problem?

        • 1. Re: Helping LPC "build a more robust solution"...
          Señor Happy Level 1

          Okee dokee. JUST saw the answer to the second part of my querry.


          I will simply scale the 'Letter' size target to half its size and have a graph that is filling only "25% to 50%" of my viewfinder for that series of shots (my lens' shortest focal length).


          However, still interested in guidance on the first part of my question, maintaining a static camera/target position then panning and tilting to achieve my 9 shots for each focal length + focus setting.

          • 2. Re: Helping LPC "build a more robust solution"...
            MadManChan2000 Adobe Employee



            It is not enough to shoot 9 images from a single position.  You really need to move the camera position, not just change the angle.  This is particularly important for longer focal lengths (say, longer than 50 mm).


            My recommended procedure is, for a given optical configuration (focal length, focus distance, f-number), shoot 9 images.  In each of the images, the chart should cover roughly 1/9th of the frame (e.g., 1/3 in each dimension).  Shoot the images as follows:


            1.  Shoot 3 images from a fixed "center" position.  The first shot can have the chart in the center of the frame.  For the 2nd and 3rd shots, rotate the camera up and down, respectively, so the chart appears along the bottom-center and top-center of the images, respectively.


            2.  Do the same as #1, but move the camera to the left.  Do not change the focus on the lens.  Adjust your position so that the chart remains in focus.  This will result in 3 more images.  One of them will have the chart aligned with the left-middle of the image, another with the top-left corner, and another with the bottom-left corner.


            3.  Do the same as #1, but move the camera to the right.  Again, do not change the focus on the lens. 

            This will result in your final 3 images.  One of them will have the chart aligned with the right-middle of the image, another with the top-right corner, and another with the bottom-right corner.


            Thus, in summary, shoot 9 images, 3 each from 3 different positions.


            To give you a visual example, see this document


            http://www.adobe.com/special/photoshop/camera_raw/lensprofile_creator/lensprofile_creator_ userguide.pdf


            and go to Page 8, and look at Step 5.  There is an illustration of the Lens Profile Creator software, and if you look closely at the bottom of the window, there is the filmstrip at the bottom with thumbnails showing the images shot for a single optical configuration.  They show how the chart occupies roughly 1/9 of the frame, aligned with various edges and corners.