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R
rqfugate
Participant
May 18, 2019
Question

Anyone get Flat-Field Correction to work? - LR Classic 8.3

  • May 18, 2019
  • 5 replies
  • 4213 views

What am I doing wrong? Position Calibration file and RAW file next to one another in the Library Grid view. Select both files. Library ->  Flat-Field Correction -> default boxes checked. No DNG file produced. Progress bar runs in a few seconds. Nothing comes out. No error messages. No DNG file anywhere on the computer. Tried checking other boxes in the dialog - no change. Same on both Desktop and Laptop same behavior. Mac OS 10.13.6. Stumped.

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5 replies

GoldingD
GoldingD
Legend
May 26, 2019

Ahh a much much better discussion on how:

Adobe Flat Field

    Todd Shaner
    Todd Shaner
    Legend
    May 26, 2019

    I already posted that link in my reply #8 above. As I suggested let's continue the discussion at the above mentioned Photoshop Family post. This is the best way to get Adobe's attention and have them address the current usability issues with the Flat Field correction tool in LR Classic.

    GoldingD
    GoldingD
    Legend
    May 25, 2019

    Having looked at:

    https://laurashoe.com/2019/05/14/whats-new-in-lightroom-classic-8-3-may-2019-release-new-features-and-more/#flat

    Are you sure that the DNG file was not created and the original RAW file removed from the catalog, and you are looking at the new DNG?

    Todd Shaner
    Todd Shaner
    Legend
    May 26, 2019

    davidg36166309  wrote

    Having looked at:

    https://laurashoe.com/2019/05/14/whats-new-in-lightroom-classic-8-3-may-2019-release-new-f eatures-and-more/#flat

    Are you sure that the DNG file was not created and the original RAW file removed from the catalog, and you are looking at the new DNG?

    A request to retain the original raw file in the catalog along side the Flat Field DNG file has been made at the below Problem report. I also added the issue of astrophotography images being detected as calibration frames. Please add all further comments at the below link along with your 'Me To' vote and 'Follow.' Thank you.

    New Flat-Field Correction DNG should not remove/replace the original RAW in the catalogue | Photoshop Family Customer Co…

    GoldingD
    GoldingD
    Legend
    May 25, 2019

    Looks like part of the issue is the clear as mud instructions at Adobe,at least the following one:

    Flat-Field Correction

    First or last image included in a selection of images to be corrected must be the calibration frame. Lightroom attempts to if determine first or last is it, chooses one, and treats either those following it as normal, Just how does LR determine that, and what if it gets it wrong. And does our sort order effect what lightroom thinks is first or last. And just how to create the calibration frame.

    So, on to searching for better info?

    Here is one, hmm, this is where I noticed an expo-disk mentioned;;

    https://lightroomkillertips.com/may-2019-update-for-lightroom-classic-lightroom-and-adobe-camera-raw/

    That page seems to treat this a a one image correction.

    Oh and:

    https://laurashoe.com/2019/05/14/whats-new-in-lightroom-classic-8-3-may-2019-release-new-features-and-more/#flat

    GoldingD
    GoldingD
    Legend
    May 18, 2019

    I see that some of the Adobe online directions were calling for or perhaps. recommending using a plastic diffuser card, an an example of that would be a Expo-Disk (and now I cannot provide a reference on that).

    One source talks about using a flat white wall.

    Adobe Flat Field

    R
    rqfugateAuthor
    Participant
    May 18, 2019

    New information.

    On my computer:

    Flat-Field Correction works on .RAF Fuji files and Nikon D810 .NEF files but NOT D850 .NEF files.

    GoldingD
    GoldingD
    Legend
    May 18, 2019

    To ask a dumb question, And, no, I have not used this yet, so perhaps very dumb.

    For the D850, you used a calibration image specific to that camera and the lens in question? Not using one shot in the D810.

    Different metadata for camera.

    Todd Shaner
    Todd Shaner
    Legend
    May 19, 2019

    Could those concerns be mitigated using:

    • A display known to have excellent uniformity, such as the more expensive NEC and Eizo displays
    • Focusing so that the display is completely out of focus, to blur moire
    • Using a very long shutter speed to take care of the display refresh rate

    Below is a Calibration file created using my very uniform NEC PA272w monitor with the central 2/3 area of the screen filling the camera's frame. I can see streaks caused by moire' interference and speckles due to small non-uniformities in the screen. Whether or not this will affect the Flat Field DNG is dependent on the sample size Adobe has selected for calculating the vignetting and color shift correction. You can check your Calibration files by moving the LR Tone Curve end points inward to the sides of the histogram data as shown below.

    Adobe needs to provide much more detailed user Help information concerning HOW to create the Calibration image files to insure the most accurate results.

    Flat-Field Correction

    "For best results, shoot the calibration frame with a plastic diffuser card under the same optical configuration i.e. same lens, f-stop number, focal length, focal distance etc. to create the calibration frame."

    What diffuser card, how uniform does it need to be, what type of lighting, how do you insure uniformity concerning all of these possible influences. Remember, we are trying to correct small lens anomalies. If the Calibration image file also has equal or larger anomalies then we are not going to achieve proper correction.

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