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Thread: IQ160 tiling issue

  1. #51
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    Re: IQ160 tiling issue

    Quote Originally Posted by Paul2660 View Post
    I have seen the "ripple" effect with both the 160 and now 260. This is with mainly the SK35 on shifts of more than 6mm.

    I used the 160 for over a year and did not notice I was getting it, however on a shot I took in the fall of 2013 where I was shifting in low light 15mm with the SK43, I saw it in spades. I was also using the 40mm Rod (testing) and did not see this problem, so I figured it was an issue with the 43SK and IQ260.

    I inquired with DT and they confirmed this, and also stated that the LCC should remove it in post.

    When I worked up the 43mm shot, the LCC (when processed no loaded in C1) did removed most of it, however some was still present. The 40mm shot was much cleaner.

    I then went back over some of my shots from 2013 and started to find places where I had gotten this, just not noticed it since I did not have a sky or solid color involved. Again worst offender was the SK35, with a few problems from time to time with the SK43.

    I did find a series in brighter light, that C1 (7.2) would not totally resolve the issue with some shots taken with the SK35. The issue was mainly in a shot that was around 9mm of shift which is pushing that lens too much on a 160-260. There was enough loss of color saturation that the portion of the image that had it the worse was cropped.

    However both 160 and 260 can show this problem at times.

    I can't see how the Canon 17mm TS-E would get it since it's out so much further from the sensor, however I would figure that you could take an LCC just like on a tech camera and apply it? I have never tried this but had though of doing it just to help with the light fall off. One of these day's I may try it with my 24mm TS-E II on a 6D.

    I have never opened any of my shots from the tech camera in LR as I don't prefer their LCC process (tried it but never could figure it out). However it's interesting that the problem files open clean in LR (the ones from the DF).

    Paul
    An LCC with the 17 TSE would be tough to pull off due to the front element of that lens.

    If anyone has a curved LCC plate that could be used, I'd be more than happy to buy it off them!

    Kind regards,

    Gerald.

  2. #52
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    Re: IQ160 tiling issue

    Quote Originally Posted by gerald.d View Post
    If anyone has a curved LCC plate that could be used, I'd be more than happy to buy it off them!

    Kind regards,

    Gerald.
    For what do you need a curved LCC-plate? It must be possible to use the 17mm Canon with a Lee Filter-holder:

    DIY Canon TS-E17mm filter holder - YouTube
    (and part II)

    or
    LinsenSchuss.de - Fotografie von Dane Vetter | Hobby Fotograf aus Jestetten - Canon TS-E 17mm f/4L Filterhalter
    (but this is in german)

    And if you could mount the Lee-holder you would have different options: the Lee front cap or perhaps a 45% plexiglas (I use this) or changing the Filter Guides to a wider version (possible is 1, 2 and 4mm), so that you can use your own LCC-card.

    There's actually no system directly from Lee like the SW-150 for the Nikon 14-24, but if you have some time to craft, it should be possible.
    __________________
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    P.S.: If your wife knows everything... it's mostly not good for your gear.
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  3. #53
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    Re: IQ160 tiling issue

    Neither of those are designed taking into account when the lens is used on a MFDB. You'd get significant vignetting unfortunately.

    Something like this might work though...



    (frosted glass lamp shade)

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    Re: IQ160 tiling issue

    Gerald, I'd experiment with acrylic balls as used for decoration:

    http://www.decowoerner.com/en_GB/Acr...-1-4767.2.html

    Not sure if you get them in white. If not, you would have to try a small sandblaster.

    Chris

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    Re: IQ160 tiling issue

    Peter,

    I think it is a common problem. Several people have had similar problem.
    I bought a brand new IQ180 when it first came out and had to change to a new one which continued having problems off-and-on especially with B&W. I was told it was caused by the border of sensor stitching.
    It's more prominent in the sky and with B&W especially after contrast adjustment.
    You are not alone. I would contact the dealer and have the back calibrated or changed.

    Pramote

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    Re: IQ160 tiling issue

    Pramote,

    Thanks, I'm in the process of getting it sorted out. Will let you know of the outcome..

    Peter
    Peter
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    Re: IQ160 tiling issue

    Done some extensive testing with C1 7.2.2 today, and the only conclusion I can come to at this point is that

    1) Capture One has a tiling suppression algorithm, ie it does not only rely on calibration data and/or LCC, it also tries to suppress tile lines further after calibration data is applied (which probably is a good idea as calibration data cannot be 100% perfect)

    2) This tiling suppression algorithm can in some situations go haywire and make things worse rather than better.

    I was confused with a tile line that showed up in C1 but was invisible in RawTherapee. Programmer as I am, I modified the raw file by shifting the image data 500 pixels to the side and then reopened it in C1. You'd think that the tile line would move 500 pixels to the side right? Or perhaps stay in the same position where the actual sensor tile is. Neither of that happened, instead the tile line disappeared! This made me come to the conclusion above. That is when the image was shifted the tiling suppression algorithm got new image data to work with and succeeded that time.

    I don't have the C1 source code of course so I cannot say for sure that I've described how it works correctly, but the current version surely has some issues with the tiling suppression.

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    Re: IQ160 tiling issue

    After further testing it seems like 1) this sometimes-failing tiling suppression algorithm is not run in tethered mode (ie then tiles go away), and 2) it's not run for P65+ but it is for IQ160, ie if I change tags so that C1 thinks the IQ160 file is a P65+ file the tiling issue goes away. Tested with 7.2.2.

    So if you're an IQ160 owner and experiences tiling issues you can do a sanity check and see if the problem is still there in tethered mode. If it disappears then, it's not a problem with the back's calibration, but with C1.

    I've done this investigation as a part of IIQ format compatibility testing in RawTherapee and Lumariver HDR (where I contribute to development), using C1 as reference... I've been pulling my hair why tiling has appeared in C1 when it was not there in the other programs. If someone is going to make a bug report to Phase One I can contribute with some technical details from my investigation, or just refer to this thread. A C1 developer which knows how the program is designed will realize in minutes what the problem is. It's a lot harder for me that can only see how the program reacts to changes I make to the raw files.

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    Re: IQ160 tiling issue

    For everyone's information I got my IQ160 replaced. My dealer arranged for me to test a number of backs and pick the one I found best.
    It is way better than the first unit, but still show tiling/lines when using my Cambo with Rodie 40HR, SK60XL and SK120 ASPH. However my prelimary findings is as torger writes that the tiling disappears when shooting tethered which also was what was happening with the issues I had with the Aptus-II 10 I had briefly but returned for this reason.
    I will do some more testing shooting the same files tethered and to CF and see what it shows.
    More later...

    Peter
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    Re: IQ160 tiling issue

    The whole thing about it going away when tethered, is odd. I can't see why C1 would use a different algorithm. However since I am now tethering as often as I can with the 260, I will try to check some of my files on a day when I shoot both ways.

    Edit:

    After more thought on this, I guess it could be due to the fact the the tethered images are loaded directly into C1 and non-tethered are on the card and don't have anything loaded until you import them into C1. However it has always been my understanding that no algorithms are run for tiling/center folding/edge rippling until you process the LCC in C1. When you tether, you still don't process the LCC as it's recorded in the Capture Folder.

    Still an interesting issue.

    Paul
    Last edited by Paul2660; 9th May 2014 at 06:16.

  11. #61
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    Re: IQ160 tiling issue

    Only Phase One knows for sure... it's quite easy to get confused as tests go either this way or the other, so I cannot say for sure I'm describing things correctly. What I do know 100% certain is that the current C1 does under some circumstances introduce tile lines which are not there in the raw data, even before LCC. This must be classified as a bug in C1. It's harder to figure out exactly under which circumstances this occurs.

    The calibration data embedded in the back (and raw file) should remove tiling to a very high degree, if your back is properly calibrated you should not have any problem in normal use. If you use a 645DF and only do typical image processing you probably never have any problems. However with technical wides tiling can get a little bit visible anyway (as the sensor changes behavior slightly with tech wides), and/or with super high contrast processing (as calibration cannot be 100% exact) and then you need to apply LCC or in some other way suppress tile lines.

    Actually I do not know if C1's LCC algorithm does support tiling suppression (they store LCC in a compressed format, and if that means 2D blurring, it won't be good for tiling removal), or if there's a separate algorithm that suppress tile lines without LCC guidance. Both is possible.

    The problems we've seen indicates that there is a tiling suppression algorithm in there, which currently is unstable and does mistakes now and then (depending on exactly what pixels that are along the tile lines, explaning why behavior is so confusing, ie works sometimes, fails sometimes). Adobe's DNG converter also have a tiling suppression algorithm (I've asked Adobe's developers), so it's not unlikely that C1 also has it.

    Latest on tethered vs non-tethered is that it you can get the opposite behavior. To me this indicates that it's not about that, but simply about what exact pixels that are in the image, even if images are almost exactly the same there will be some pixel differences and if a tiling suppression algorithm is unstable it can throw it off on one image and not on the other.

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