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Thread: LCC / white sheet?

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    LCC / white shading?

    (Ack, white shading, not white sheet)

    I am trying to learn about LCC (Lens Cast Calibration?) files (in Phase One terminology), white shading in Sinar Brumbaer terminology, but I am finding little about it.

    As I understand it, one makes an exposure with a particular lens at a particular distance with a particular aperture, of a particular scene, and uses this to correct the lens cast in the file.

    A shortcut is to do a general LCC file of a white wall, evenly lit, but this will not give full correction in all cases.

    How does this work with Sinar Exposure? Is it possible to convert Sinar back files to DNG and to use LCCs in Capture One?

    Thanks for any information on this.
    Last edited by carstenw; 5th November 2008 at 14:57.
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    Re: LCC / white sheet?

    Carsten:

    The LCC feature in Capture one only works with a Phase back file. The function is disabled with other RAW file types.

    Robert

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    Re: LCC / white sheet?

    If you are using a Sinarback and you want to apply a user shading file to a shot, I believe you can only do it after having creating a user shading previously, then selecting it at the time of shooting tethered. This is true with the current version of eXposure anyway (6.0.1) but I believe future versions will have the ability to apply a user shading file retrospectively to a shot.

    The way to do it using eXposure is as follows:

    1. Cover the lens with an opaque white piece of plastic, ideally the Sinar filter part# 551.43.098
    2. Shoot an exposure with even light coming through the filter, (for example directly into a softbox) and neutralize the shot using the color picker. The color values in the centre of the shot must be in the high 240's or low 250's - not blown out and with a linear curve, and no contrast or brightness applied. Any lower RGB values than this will create more noise when a shot is done with the resulting user shading applied.
    3. Activate the Shading Calibration function from the Capture menu.
    4. Capture another shot with the opaque filter covering the lens agin using the same exposure as before.
    5. Save the resulting file giving it a name that refers to the lens used and aperture e.g Contax 80mm f5.6
    6. Close the Shading Calibration function.
    7. Go to the Capture tab in the Controls 'dockwidget'.
    8. Go to the Shading Calibration plugin and select the newly created file from the list. If it is not there, quit and restart the software.
    9. Take a new shot of a neutral target such as a grey card with the new Shading Calibration selected. the color will be way off, so neutralize the new shot.
    10. All files shot subsequently will have the new Shading Calibration applied to them. Beware - whenever you restart the software the default factory shading file is selected, so you must always manually select a file before each shoot. I have also found that sometimes the selected shading calibration file will mysteriously go back to the factory setting, so keep an eye on it during your shoot.
    11. You can create a library of Shading calibration files with different lenses and apertures in the studio under controlled conditions so that whenever you are out on a shoot you simply need to select the appropriate file to suit your lens and aperture before you take a shot. As I said above, I believe future versions of eXposure will allow you to apply these files after a shoot, so you could shoot untethered then apply the shading cal files in post processing.

    In my experience with the 33mpx Dalsa chip (eMotion 75LV) a shading file is *essential* due to the color shifts in the factory file, even when using a standard lens. See example below - Standard Contax 80mm at 5.6, left shot with factory shading, right shot with my shading cal file applied. Notice the green centre and magenta edges in the left hand shot. (ignore the dirty marks on my color card!)

    I don't know how to apply a shading file with Brumbaer software, but I believe there might be a way.

    Ben
    Last edited by bdp; 5th November 2008 at 19:00.

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    Re: LCC / white sheet?

    With the Phase back in C1, you set your shot up, shoot a normal frame and the white frame. Then in post, you open the LCC file, generate the LCC correction, then open the regular image and apply the LCC correction. You done
    Jack
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    Re: LCC / white sheet?

    Yeah, I've probably made it sound more complicated than it really is, but a few of the finer points make a difference, such as careful attention paid to the exposure during the shading file creation. It's a very quick process, and once you've got your library of shots you will be able to apply them just like in the Phase software, when the next version of eXposure is released.

    Ben

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    Re: LCC / white sheet?

    Compared to the Phase workflow, the Sinar seems very complicated! On a technical camera, shifts also come into play, so there's no way but to do the LCC on every shot. I'm sure Rainer V has an easier explanation of the steps required, as well as the Brumbaer workflow. Rainer, if you can add to this?

    Cheers,
    Kumar

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    Re: LCC / white sheet?

    Yes, to do one on location to suit the particular movements of a technical camera, you would just hold the diffuser over the lens and increase your exposure about 1.5 to 2 stops to get a nice bright shading file, save it, then select it and shoot your shot. Pretty simple. Of course you can only do this if shooting tethered at the moment with eXposure. After eXposure 6.1 is released it will be just as simple as with the Phase software, even simpler, and you will be able to shoot untethered shading ref files then batch apply them to shots previously taken. This is, I believe, how the Brumbaer DNG converter does it at the moment.

    Ben
    Last edited by bdp; 5th November 2008 at 21:01.

  8. #8
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    Re: LCC / white sheet?

    Wow that was a very detailed explanation! I make these files all the time and I would have never thought it could be so complicated until I saw it writen down!
    Here's the deal; Phase users will always tell you how easy it is to do everything - like "Boom- you are done" and the same is the case in the Sinar software - only you can also take things to the "next" level if you wish. In fact, in both Captureshop and eXposure, all you need to do is go to the "Capture" pull-down menu and follow the step by step instructions and guess what? You're done!

    There are 3 different types of correction files you can make.
    1. You can make a sensor file (useful if you scuff the cover glass etc.)
    2. You can make a lens reference (this is the type that most will make using a white plexi disk in front of the lens to even out bad illumination from lens casts, or mixed lighting scenarios, or view camera movements, or fall-off from wide lenses etc)
    3. You can make a Scene reference (mostly used by art repro people to even out the illumination on the painting etc).

    Truthfully, it should take you no more than a minute to make and apply this file.

    I have not seen the newer version of eXposure where you can make the files before, during or after the shoot (or untethered) but it will be released in the next few weeks.

    The way it works in Brumbaer is very clever as it allows for a fully automated workflow and I would expect that eXposure will do something similar. Brumbaer date and time stamps every file and what this means is that you can name your reference file to fit into the time slot you want. In other words, when you start to process the files they will automatically use the white reference on all the shots until the next time stamped refernce file appears and then it starts applying the new file and so on. That's why Rainer loves that tool so much, because he can let his computer do all the work while he hangs out at the pool or bar or whatever....

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    Re: LCC / white sheet?

    Yes, in reality it is simple, but some new users might like to be hand-held through the steps for the first time they do it, hence my detailed explanation!

    Really you can start at step 3. Steps 1 and 2 only ensure you have a good exposure to get the best possible shading file. I could have just said: 1. Pull down the shading cal option and capture a shading file 2. Save it and select it for next capture - that's it, but I thought people might like to know how to do the process in detailed steps, and how to get the best out of it. Once you've done it once or twice it is second nature.

    Looking forward to 6.1 if it does the shading refs as smartly as Brumbaer!

    Ben
    Last edited by bdp; 5th November 2008 at 22:10.

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    Re: LCC / white sheet?

    Ben, thanks a lot for the detailed explanation. Since I will initially be shooting untethered, I guess I am stuck just using the factory shading file for now, or switching to Brumbaer until 6.1 comes out, but that is fine since I will be learning the system and workflow for a while anyway.

    I guess in the end I will try all three shading files, just to make sure that I am comfortable with them, but I doubt I will do a scene shading unless needed. I guess I need to develop a feel for that.


    With Brumbaer, is it possible to "bake" the lens cast correction into a DNG and continue working in another package?
    Carsten - Website

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    Re: LCC / white sheet?

    Hi Carsten,

    Yes, if you read Stefan's explanation of how eMotionDNG works at http://www.brumbaer.de/Tools/Brumbaer_Tools.html he says "eMotionDNG allows the use of white reference files to remove color casts, supports calibration with Gretag Color Checkers, removes centrefolds and has an advanced highlight recovery".

    How to actually do it is another question. I'm sure a search on here or an email to Stefan will explain it.

    Ben

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    Re: LCC / white sheet?

    Thanks again, Ben.
    Carsten - Website

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    NHScottishGuy
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    Re: LCC / white sheet?

    Carsten,

    When you say "bake' into the DNG I think you mean will it always be a part of the file? In this case - yes. The Brumbaer tools is not a software that really takes any great learning. Essentially what it does is converts your Sinar eMotion BR and AI files into a DNG ready to go anywhere. As part of that process it applies White Ref files and any color matrix that you provide via capturing of a Macbeth chart etc.
    So I guess to answer your question, the references are baked into the DNG pie.

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    Re: LCC / white sheet?

    Dave,

    yes, that is what I meant, thanks. I don't have the back yet, so I am mentally trying to prepare by going through workflow in my head, and trying to figure out what knowledge I am missing, so that I can get moving quickly once I have the back, so some of my questions might sound a little weird.
    Carsten - Website

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    Re: LCC / white sheet?

    Carsten you should try and get the software that comes with the back you are thinking about and get some raw files from folks here and see if that workflow fits your needs and without driving you crazy.
    Photography is all about experimentation and without it you will never learn art.

    www.guymancusophotography.com

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    Re: LCC / white sheet?

    Quote Originally Posted by Guy Mancuso View Post
    Carsten you should try and get the software that comes with the back you are thinking about and get some raw files from folks here and see if that workflow fits your needs and without driving you crazy.
    Great idea, Guy. I had thought of that earlier, but forgot about it again.
    Carsten - Website

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    Re: LCC / white sheet?

    Quote Originally Posted by bdp View Post
    Yikes! Does Sinar's software have chromatic aberration correction like Capture One? That's a pretty obtrusive green chromatic aberration halo.

    Doug Peterson, Head of Technical Services
    Capture Integration, Phase One Dealer | Personal Portfolio

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    Re: LCC / white sheet?

    While for simplicity of workflow it might be easier to take a shot at the beginning of any new sequence I would point out the following factors which do and do not make a difference from our experience with Phase One backs:

    aperture: minimal*
    focus-distance: moderate (if the change is large)
    shutter speed: none
    lens length: major
    lens shift/tilt: major

    *in this case I define "minimal" as "you could measure it, probably, but it will not be significant"

    Doug Peterson, Head of Technical Services
    Capture Integration, Phase One Dealer | Personal Portfolio

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    Re: LCC / white sheet?

    Carsten,

    Here is a link to Phase One's Knowledge Base to show you and tell you about LCC.

    Mac LCC:

    http://www.phaseone.com/HOME/Content...ite%20-%20Main

    Windows/ PC LCC:

    http://www.phaseone.com/HOME/Content...ite%20-%20Main

    Chris Lawery
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    877-217-9870 | National Atlanta / Miami
    404-234-5195 | Cell
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    Re: LCC / white sheet?

    Thanks, Doug and Chris, I will read my way through that.
    Carsten - Website

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    Re: LCC / white sheet?

    Quote Originally Posted by carstenw View Post
    Great idea, Guy. I had thought of that earlier, but forgot about it again.
    I know C1 you can get a demo mode from the past , pretty sure you can today. Not sure on Phocus, Leaf or Sinar software though have to check on there sites
    Photography is all about experimentation and without it you will never learn art.

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    Re: LCC / white sheet?

    Quote Originally Posted by Guy Mancuso View Post
    I know C1 you can get a demo mode from the past , pretty sure you can today. Not sure on Phocus, Leaf or Sinar software though have to check on there sites
    Leaf Capture is free so there's no demo version. Some raw files are available on our website but not these "specialised" ones.

    Our custom gain workflow/s might be combining the best of all worlds, with three main pluses:

    1. The corrections are embedded into new raw files that can be archived and/ or converted in any 3rd party converter
    2. Falloff (vignetting) correction can also be embedded into these new raw files
    3. For tethered shooting there's a wizard that guides you how to create and load a custom gain file

    Post shoot correction:

    1. Shoot a gain file (using the supplied diffuser filter) at the beginning/ end of a sequence of shots. If you change the aperture and shift, shoot another gain file. The filter takes about 2 stops so you have to compensate by using longer exposure.

    2. In Leaf Capture, select "Leaf MOS" as the processing format and press "settings":



    Select the preferred method and type in the required fall-off correction.

    3. Select the gain file and the images that need to be corrected and press "process"

    This will create new copies of RAW files that are corrected and ready to go into any 3rd party converter or archiving (this applies to Moire reduction as well BTW).

    Shooting tethered:

    You can use the same workflow as above or you can use a wizard that will guide you through creating a custom gain file and loading it to the back:




    Etc.etc. or you can load a file that was created/ stored before:



    Here's a before/ after with 15% falloff correction:



    Hope this helps, the whole process is described in the LeafCapture help guide

    Good night from Copenhagen.
    Yair
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    Re: LCC / white sheet?

    Thanks Yair for jumping in there
    Photography is all about experimentation and without it you will never learn art.

    www.guymancusophotography.com

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    Re: LCC / white sheet?

    And those who don't want to use Leaf Capture, they can use the Custom Gain Adjuster which is a standalone batch utility so they can go straight into LR/ Aperture with corrected RAW files.

    Yair
    Yair Shahar | Product Manager | Phase One | Mamiya Leaf
    e: [email protected] | m: +44(0)77 8992 8199 | yaya's blog

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