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Author Topic: Sensor artefacts  (Read 2313 times)
Lakelander
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« on: May 28, 2013, 03:58:38 AM »
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I have just purchased a P65 DB which is my experience of MF digital.
Looking at the LCC images I have taken I am seeing a slight artefact
In the image. A checker board effect roughly in 6 segments split down
the middle of portrait format image. Although very slight it is visible
though I doubt if it could be seen on an actual image.
I can't find a previous thread covering this, I would like to know more.
Thanks All

Lakelander

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Doug Peterson
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« Reply #1 on: May 28, 2013, 04:33:35 AM »
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I have just purchased a P65 DB which is my experience of MF digital.
Looking at the LCC images I have taken I am seeing a slight artefact
In the image. A checker board effect roughly in 6 segments split down
the middle of portrait format image. Although very slight it is visible
though I doubt if it could be seen on an actual image.
I can't find a previous thread covering this, I would like to know more.
Thanks All

Do you see it in capture one v7.1.2 or in third party software?

Are you using a tech/view camera or SLR?

Is the line visible before adjusting the image or only after severe adjustment (e.g. an s-curve+curves+levels)?

A correctly calibrated and properly functioning back will not show any such lines if:
- viewed in up-to-date capture one
- using supported lenses (e.g. not Schneider 24XL)
- reasonable photographic adjustments
- running up-to-date firmware

If using third party software it's even more important to make sure you are up to date since some of the early implementations of support in LR and ACR were especially poor/ugly. You'll most likely find capture one does a better job of rendering the phase files anyway, but to each his own.

It is rare, but possible, for a back to be out of calibration. If in warranty, or if recently purchased from a dealer then this would be a free service. If out of warranty and purchased privately it would be a paid service, so if you've just purchased this back used from a private individual you'll want to figure out if you're in calibration ASAP so you can return it (or negotiate for the seller to pay for the required service). If you bought from a good dealer the back would have been tested for calibration prior to sale (at least we do this, I assume other good dealers do as well) but just call them and they'll take care of you (including helping you determine it you have a problem in the first place).
« Last Edit: May 28, 2013, 04:48:43 AM by Doug Peterson » Logged

DOUG PETERSON (dep@digitaltransitions.com), Digital Transitions
Dealer for Phase One, Mamiya Leaf, Arca-Swiss, Cambo, Profoto
Office: 877.367.8537
Cell: 740.707.2183
Phase One IQ250 FAQ
torger
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« Reply #2 on: May 28, 2013, 05:51:30 AM »
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When viewing a single LCC file the contrast is usually auto-increased to unnatural high levels, making these lines more visible. Digital backs usually employ multiple readout channels which cause some slight variation between segments, it's never 100% perfect, so if you increase contrast of an LCC to maximum you'll see it on any back with multiple readout channels. But the differences are so small that it's not a problem in real image making.

However, in rare occasions the back is poorly calibrated causing the differences to be unnaturally large so it actually becomes a problem in real image making, then it must be sent back to the dealer/factory for recalibration.

Unfortunately I'm not aware what the limits are and how to check them, ie how to know if your back is behaving within the tolerance level or if it is in need of re-calibration. A single LCC shot contains all the information needed to make such a check, but I don't know of any tool that can analyze it for this particular issue.
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Doug Peterson
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« Reply #3 on: May 28, 2013, 06:21:39 AM »
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Just one minor correction torger: some backs require factory service, some backs can (in nearly all cases) be calibrated in the field. Notably phase one p+ backs do not require a trip anywhere and can be almost always calibrated via a dealer <48 hours (often quite fast) by simply sending a few files back and forth.
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DOUG PETERSON (dep@digitaltransitions.com), Digital Transitions
Dealer for Phase One, Mamiya Leaf, Arca-Swiss, Cambo, Profoto
Office: 877.367.8537
Cell: 740.707.2183
Phase One IQ250 FAQ
Lakelander
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« Reply #4 on: May 28, 2013, 12:55:09 PM »
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Thanks Doug and Torger

I only have Lightroom 3 at the moment until I get a WiFi connection sorted.
Then I can use Capture DB software to view files, I will be buying Capture one 7.
I'm using a Alpa TC and Schneider Alpa Helvetar 28 5.6 XL with P65+.
LCC card from Phaseone +2 stops and +3 stops same artifacts.
I'll check with dealer about firmware ?
And post an image of the artifacts..

Thanks for the help (:
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Lakelander
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« Reply #5 on: May 28, 2013, 01:37:06 PM »
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Here is an enhanced shot off the LCC image, corner of artifact near dust spot top right.
I have cleaned the sensor since this shot Lol
Firmware -
Main  5.2.2
Boot  2.3
FPGA 1.2.4
DPLD 1.0
PAVR 1.0.3
UIFC 1.0.1
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gerald.d
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« Reply #6 on: May 28, 2013, 01:37:47 PM »
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I believe I'm right in saying that you don't need to pay anything to use Capture One with a Phase digital back.
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Chris Livsey
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« Reply #7 on: May 28, 2013, 01:49:16 PM »
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I believe I'm right in saying that you don't need to pay anything to use Capture One with a Phase digital back.

Correct, I own a venerable P20 and have the luxury of running the latest Capture One release.
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Doug Peterson
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« Reply #8 on: May 28, 2013, 02:58:12 PM »
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I believe I'm right in saying that you don't need to pay anything to use Capture One with a Phase digital back.

Right on.

To elaborate there are three versions/editions of Capture One:
Capture One LE - a "lite" version with fewer features
Capture One DB - all features, but only works with Phase One / Leaf digital backs
Capture One Pro - all features, and works with Nikon/Canon/etc

Basically it's free to use their software with their own hardware but costs $ to use their software with other manufacturer's hardware.
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DOUG PETERSON (dep@digitaltransitions.com), Digital Transitions
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Doug Peterson
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« Reply #9 on: May 28, 2013, 03:01:30 PM »
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Here is an enhanced shot off the LCC image, corner of artifact near dust spot top right.

Best to work with your dealer on this I think.

There aren't many of us that can examine a file from an exotic combination like the Schneider 28XL and the 65+ and no what baseline to compare against, and we'd only want to examine the raw file, not a screen grab or processed jpg from older versions of third party software.

You might find this reference chart detailing the compatibility of various lens+back combos useful:
http://www.digitaltransitions.com/page/tech-camera-overview

That chart is contingent on using Capture One and it's "wide angle tech cam" LCC option.
« Last Edit: May 28, 2013, 03:13:28 PM by Doug Peterson » Logged

DOUG PETERSON (dep@digitaltransitions.com), Digital Transitions
Dealer for Phase One, Mamiya Leaf, Arca-Swiss, Cambo, Profoto
Office: 877.367.8537
Cell: 740.707.2183
Phase One IQ250 FAQ
Lakelander
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« Reply #10 on: May 29, 2013, 07:15:40 AM »
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Thanks All

I will leave the issue to one side until I am up to date with software and
have read Doug's reference document Thanks for the Doug Smiley

My dealer said it was the physical CCD spacing lines, which sound's sensible.

Either way Thanks for your help

Lakelander
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torger
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« Reply #11 on: May 29, 2013, 07:25:59 AM »
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My dealer said it was the physical CCD spacing lines, which sound's sensible.

What exactly is "physical CCD spacing lines"? There should not be any gaps on the sensor as far as I know. You can probably see a slight pattern if you look at the sensor as it has been exposed multiple times when manufactured, but that should not cause pixel misalignments or gaps, right?
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Paul2660
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« Reply #12 on: May 29, 2013, 08:34:50 AM »
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No sure about that answer.    The sensor is one piece and the lines are read out's as I understand it.  It's how the data is read from the various sections of the chip helps with speed of getting the data off.   The calibration process that Doug mentioned is very key to making sure that the lines will be removed during the raw conversion.   In the vast majority of shooting situations, they should not show up in the converted raw file as the back should be correctly calibrated.  I don't think  the lines are gaps, as if they were then some form of image interpolation would have to be done to create the pixels to close the "gap". 

All 60mp and 80mp Phase chips show these lines.  I can't speak to Leaf or Hassi.  The older Phase chips, 39mp CCD from Kodak did not show these lines.

Your LCC may show these, but the calibration that Doug referred to should remove this in all but the most extreme situations.  Some people call these lines centerfolding or tiling and you can search on the web as there has been a lot written about this issue.   The SK28 may have an issue like my SK43, but still in most situations the lines should be taken out in Capture One.  There was a very good review of the SK28 and Rod 28 on www.getdpi.com review section and no issues of centerfolding/tiling were mentioned.   The review was done using a IQ160 which has the same chip as the P65+.  The review is a very good read.

Here is a link:  http://www.getdpi.com/forum/lens-accessory-reviews/34991-rodenstock-28mm-hr-vs-schneider-super-digitar-28xl.html

The back and Capture One should remove the lines and as your LCC's load into Capture One you should see the lines disappear as the LCC is browsed by Capture One. 

I often see the tiling when I look at my LCC"s on the IQ160 LCD, but in 98% of the time they are totally removed in Capture One.  If I shift my 43SK to extreme amounts (15mm or more) or underexpose the frame I might see some tiling.  The 43SK is known for this issue.  The Rodenstocks don't seem to have this issue.  Tiling also seems to show up on the screen more on shifts then center images. 

Definitely get Capture One loaded and try it on the effected files.   You may need to open a case with Phase One, is there any warranty on the back? 

Paul Caldwell

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Paul Caldwell
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Doug Peterson
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« Reply #13 on: May 29, 2013, 10:38:25 AM »
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I often see the tiling when I look at my LCC"s on the IQ160 LCD, but in 98% of the time they are totally removed in Capture One.  If I shift my 43SK to extreme amounts (15mm or more) or underexpose the frame I might see some tiling.  The 43SK is known for this issue.  The Rodenstocks don't seem to have this issue. Tiling also seems to show up on the screen more on shifts then center images.

The issues that appear with a 80mp + 43XL combo with large shifts is what is being referenced by the word "limited" in our compatibility chart in our Tech Camera Overview. With "limited" combinations the final image will be immaculate with limited movements, beyond which you'll see (subtle but meaningful) uncorrected tiling and loss of color fidelity.

The moderately-retrofocus design of the rodenstock wide angles avoid this issue at the cost of increased lens weight/size/cost and a small amount of distortion.
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DOUG PETERSON (dep@digitaltransitions.com), Digital Transitions
Dealer for Phase One, Mamiya Leaf, Arca-Swiss, Cambo, Profoto
Office: 877.367.8537
Cell: 740.707.2183
Phase One IQ250 FAQ
Lakelander
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« Reply #14 on: May 29, 2013, 11:19:58 AM »
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Thanks again Guys

I'm Very Happy with the images I have now and these VERY slight issues i'm sure will
be more than dealt with by Capture one.
When I was using film grain would be far more intrusive to an image.

Cheers
Lakelander
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KevinGSaunders
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« Reply #15 on: May 30, 2013, 06:48:42 AM »
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Doug,

I had to send my Afi 12 back to Israel and bring out the Aptus 75s and learned it no longer works with Capture One in DB mode. I asked Tech support to change that and hope they will.
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yaya
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« Reply #16 on: May 30, 2013, 02:34:28 PM »
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Doug,

I had to send my Afi 12 back to Israel and bring out the Aptus 75s and learned it no longer works with Capture One in DB mode. I asked Tech support to change that and hope they will.

Hi Kevin, this is not going to change I'm afraid. The DB mode works with Aptus-II and AFi-II backs but not with previous models. You need to purchase the PRO licence for that

However you can use it in Trial mode for 60 days and that is a full working version and works with your Aptus 75S

Best

yair
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torger
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« Reply #17 on: June 01, 2013, 10:19:25 AM »
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I thought I was using my 75 with C1 in db mode. Perhaps license have changed recently? I mostly use rawtherapee so it was a while ago I used C1. Would be nice with a full license anyway so I can do 35mm work in it too.
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KevinGSaunders
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« Reply #18 on: June 03, 2013, 07:28:13 AM »
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Hi Yair,

Thanks. I have a pro version, but use a laptop or a mobile cart mounted desktop for tethering. Since I have my big desktop set up as well, this means deactivating one of the computers out in the studio and it is a big pain to hand copy and type in the license code every time. I asked them to put a "remember" feature in so rapid deactivation and activation could happen, and I am eagerly awaiting it.

When my Aptus II 12R comes back from Israel for calibration and cleaning, I will not need to worry about this either!

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