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Author Topic: leaf aptus 75 split sensor-colorshift? for Jair..  (Read 23997 times)
markowich
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« on: August 12, 2006, 06:47:08 AM »
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 Dear friends,
I just noticed a very disturbing issue on (actually all) my leaf aptus 75 files.There
is a sharp color shift/contrast change across the vertical middle line of the images. It is noticable in very bright zoes and even more so in very dark zones.
When looking at the Aptus 75 sensor it becomes apparent that it consists of two equally big parts which are joined together veritically. Is it possible that the color shift stems from this sensor design issue? Actually, I should add that this color shift occurs on all my files, sometimes worse and sometimes less noticable, independent of whether I capture the images with my ALPA SWA (with Schneider Digitar lenses, 24mm and 47mm) or with my Hasselblad H1 using various lenses. I uploaded two (very big) jpgs, which show this ugly effect, on my pbase page:

   www.pbase.com/markowich

in the gallery entitled : leaf_aptus_75_test. To see it clearly, look for the vertival middle line of the images.

Both files were converted to jpg using ACR (please believe me that the colorshift also occurs when converting with Leaf Capture!!!),  no postprocessing done.
I would be grateful for an explanation and for a (software?) fix, or for advice on how to proceed further. In particular, a response of Jair, who has been very helpfully active on this forum would be highly appreciated. Of course I can provide
the original RAW files via ftp.
With best regards, Peter Markowich
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Graham Mitchell
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« Reply #1 on: August 12, 2006, 07:28:40 AM »
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Hi Peter,

I have seen this before.

Contact user 'rehnniar'. He worked with the developer of http://www.brumbaer.de/Tools/Tools.html

to optimise the developer for the e75.

At first there was the same problem you have seen, but they tweaked the processor and the seam became invisible.
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markowich
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« Reply #2 on: August 12, 2006, 08:00:59 AM »
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Hi Peter,

I have seen this before.

Contact user 'rehnniar'. He worked with the developer of http://www.brumbaer.de/Tools/Tools.html

to optimise the developer for the e75.

At first there was the same problem you have seen, but they tweaked the processor and the seam became invisible.
[a href=\"index.php?act=findpost&pid=73130\"][{POST_SNAPBACK}][/a]

Thanks for the reply! But please... let me say that I find this kind of performance
completely inacceptable for a 30 000.-  Euro technology. I am expecting a fix from Leaf in their Capture software or, maybe, my sensor is particularly bad such that it has to be replaced.
Best, Peter
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alba63
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« Reply #3 on: August 12, 2006, 12:15:39 PM »
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Thanks for the reply! But please... let me say that I find this kind of performance
completely inacceptable for a 30 000.-  Euro technology.
[a href=\"index.php?act=findpost&pid=73133\"][{POST_SNAPBACK}][/a]


Hello, I am an outsider in this topic because I only shoot a normal 24x36 DSLR, I have now seen this vertical line issue several times. What I dont really understand is that IF the sensors are really 2 24x36mm stitched together, I am a bit amazed about the price of those camera backs. A 24x36sensor doesn't seem to cost that much anymore to manufacture, however the MF backs - which have of course more advantages than just sensor size and pixels - are much much more...

Peter, I have looked at your other galleries, I was impressed by your 2005 Brazil pictures, and particulary by the Iguassu shots. Were they made with film or digital? And if digital, with a MF back or a DSLR?

regards, Bernhard
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markowich
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« Reply #4 on: August 12, 2006, 12:56:05 PM »
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Hello, I am an outsider in this topic because I only shoot a normal 24x36 DSLR, I have now seen this vertical line issue several times. What I dont really understand is that IF the sensors are really 2 24x36mm stitched together, I am a bit amazed about the price of those camera backs. A 24x36sensor doesn't seem to cost that much anymore to manufacture, however the MF backs - which have of course more advantages than just sensor size and pixels - are much much more...

Peter, I have looked at your other galleries, I was impressed by your 2005 Brazil pictures, and particulary by the Iguassu shots. Were they made with film or digital? And if digital, with a MF back or a DSLR?

regards, Bernhard
[a href=\"index.php?act=findpost&pid=73153\"][{POST_SNAPBACK}][/a]


Hi Bernhard,
thanks for the compliment! The Brazil shots were taken with a Kodak 14nx.
Best, Peter
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pprdigital
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« Reply #5 on: August 12, 2006, 01:37:41 PM »
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Thanks for the reply! But please... let me say that I find this kind of performance
completely inacceptable for a 30 000.-  Euro technology. I am expecting a fix from Leaf in their Capture software or, maybe, my sensor is particularly bad such that it has to be replaced.
Best, Peter
[a href=\"index.php?act=findpost&pid=73133\"][{POST_SNAPBACK}][/a]

There is a beta version of the Custom Gain Adjuster which will eventually find it's way into LC 10 that is available. This will eliminate the variance, although it also has the effect of raising the gamma a bit, so be aware that you don't blow highlights out. Leaf will have an adjustable slider to adjust for the gamma at a future date.

For now it is a stand alone app, and in beta form. If anyone requires it, please contact me offline: shendrix@ppratlanta.com.

So far, I have only had one customer who has reported this, so at least at this stage, it appears to be not widespread. Recall also that all digital back sensors have variances and bad pixels as a result of the manufacturing process. There is no such thing as a pristine, perfect sensor. That is why all digital backs either have a calibration file imbeddded into the firmware or on a separate CD that is essentially a re-mapping of that individual CCD, to make an adjustment for the variances and bad pixels. When you do a custom gain file, you're basically creating a re-map of that intial factory calibration.

Steve Hendrix
PPR Digital
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Steve Hendrix
markowich
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« Reply #6 on: August 12, 2006, 01:53:34 PM »
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There is a beta version of the Custom Gain Adjuster which will eventually find it's way into LC 10 that is available. This will eliminate the variance, although it also has the effect of raising the gamma a bit, so be aware that you don't blow highlights out. Leaf will have an adjustable slider to adjust for the gamma at a future date.

For now it is a stand alone app, and in beta form. If anyone requires it, please contact me offline: shendrix@ppratlanta.com.

So far, I have only had one customer who has reported this, so at least at this stage, it appears to be not widespread. Recall also that all digital back sensors have variances and bad pixels as a result of the manufacturing process. There is no such thing as a pristine, perfect sensor. That is why all digital backs either have a calibration file imbeddded into the firmware or on a separate CD that is essentially a re-mapping of that individual CCD, to make an adjustment for the variances and bad pixels. When you do a custom gain file, you're basically creating a re-map of that intial factory calibration.

Steve Hendrix


Hi Steve,
thanks for the comments and hints. I agree completely with you, there is certainly a lot of variance in the sensors....but I am wondering if mine isn't far below average....in any case I have never seen this kind of sensor behavior and I wonder if it is not
intrinsically related to the Salsa sensor architecture. I also have a P45, which does not have this problem.....
In any case I would really like to have Leaf come up with a solution soon. I just came back from a trip to China where I used the Leaf back extensively and today I realized what I got....my mistake, I should have done more extensive testing before....
Best, Peter
PPR Digital
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markowich
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« Reply #7 on: August 12, 2006, 01:55:47 PM »
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sorry, of course it should be Dalsa instead of Salsa...
Peter
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markowich
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« Reply #8 on: August 12, 2006, 02:23:03 PM »
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sorry, of course it should be Dalsa instead of Salsa...
Peter
[a href=\"index.php?act=findpost&pid=73159\"][{POST_SNAPBACK}][/a]


ps: Yair just emailed me saying that my back has to be replaced. I appreciate his fast response!
Peter
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ericstaud
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« Reply #9 on: August 12, 2006, 06:05:42 PM »
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Hello Peter,

I have the same issue.  Leaf is replacing the back.  I will be stuck with this one until they do.  Using the Custom Gain Adjuster is the only workaround (aside from switching to retrofocus lenses which don't sit so close to the sensor.  In the short term think of this as an education in what shooting super wide with the P45 is like... shoot a photo, shoot a plastic card, shoot a photo, shoot a plastice card....

I believe the problem is with a batch of sensors that LEAF received.  The problem has only been known for a few weeks I'm guessing.  The vast majority of backs are used by people on H1's and other cameras with retrofocus lenses.  As soon as you move the lens further from the sensor the problem goes away (although I am supprised this is not the case for you).  As a result, only those of us with these large format style wide angle lenses will have a problem.  I have the issue with my 60mm digitar.  It does not manifest on the H1 I use.  Lens movements also can cause the problem.

On another note, I have an Alpa 12SWA with the 24, 35, and 60 digitars.  I really want the 47 also.  How do you like your 47 on your Alpa.  It is the Helvetar, correct?  Any chromatic abberation?  Would you buy it again?  I am about ready to throw down the cash.

Thanks,

Eric
« Last Edit: August 12, 2006, 07:04:55 PM by ericstaud » Logged
ericevans
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« Reply #10 on: August 12, 2006, 08:07:09 PM »
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ps: Yair just emailed me saying that my back has to be replaced. I appreciate his fast response!
Peter
[a href=\"index.php?act=findpost&pid=73163\"][{POST_SNAPBACK}][/a]
Leaf is always fast to respond to a problem .
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rethmeier
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« Reply #11 on: August 12, 2006, 10:57:03 PM »
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A friend of mine,Steffen Jahn from Germany,had a similar problem with his A-75.
Leaf replaced his back as well.
Some of the Sinar eMotion's had a similar problem.
Obvious the problem lays with Dalsa!
Regards,
Willem.
« Last Edit: August 12, 2006, 10:58:29 PM by rethmeier » Logged

Willem Rethmeier
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markowich
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« Reply #12 on: August 13, 2006, 01:29:36 AM »
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Hello Peter,

I have the same issue.  Leaf is replacing the back.  I will be stuck with this one until they do.  Using the Custom Gain Adjuster is the only workaround (aside from switching to retrofocus lenses which don't sit so close to the sensor.  In the short term think of this as an education in what shooting super wide with the P45 is like... shoot a photo, shoot a plastic card, shoot a photo, shoot a plastice card....

I believe the problem is with a batch of sensors that LEAF received.  The problem has only been known for a few weeks I'm guessing.  The vast majority of backs are used by people on H1's and other cameras with retrofocus lenses.  As soon as you move the lens further from the sensor the problem goes away (although I am supprised this is not the case for you).  As a result, only those of us with these large format style wide angle lenses will have a problem.  I have the issue with my 60mm digitar.  It does not manifest on the H1 I use.  Lens movements also can cause the problem.

On another note, I have an Alpa 12SWA with the 24, 35, and 60 digitars.  I really want the 47 also.  How do you like your 47 on your Alpa.  It is the Helvetar, correct?  Any chromatic abberation?  Would you buy it again?  I am about ready to throw down the cash.

Thanks,

Eric
[a href=\"index.php?act=findpost&pid=73182\"][{POST_SNAPBACK}][/a]

hi eric,
the 47mm lens i have is a schneider digitar. just wonderful, (almost) no chromatic abberation, great microcontrast!
best, peter
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Graham Mitchell
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« Reply #13 on: August 13, 2006, 06:59:51 AM »
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Obvious the problem lays with Dalsa!

If I have understood the problem correctly, it is Leaf's fault, not Dalsa. The electonics (by Leaf) which extract data from the sensor and create the captured image should be mapped to handle the differences between adjacent sensor 'panels', much the same as they map out any dead pixels.
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Eric Zepeda
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« Reply #14 on: August 13, 2006, 08:38:08 AM »
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This is very helpful info. I've been on a product shoot using the A75 for the last week using LF with a sliding back and 80/120 Digitars. No problems with colorshift, and the files are beautiful. Only problem has been when shooting a really sparkly and shimmery subject, the back occasionaly freaks out. Quitting the app and/or trashing prefs solves the problem.

Overall, as a dedicated Phase user and P25 owner, I am very impressed with the A75. I think WA LF is an area that needs improvement/refinement on both Phase and Leaf systems.
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mtomalty
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« Reply #15 on: August 14, 2006, 10:20:06 AM »
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Is the sensor,that is used in the A75,actually two separate smaller components that
are joined or is the problem that some are experiencing the result of some
inconsistency in the dual readout process that Leaf employs?

Mark
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pixjohn
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« Reply #16 on: August 14, 2006, 09:57:02 PM »
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After a little more testing with my new Aptus 75 I am also a winner,

Leaf Aptus 75 Sample
 
I guess they need to start testing these backs before they ship them? Lets just hope I can take care of this before my shoot next week. I was able to get a clean file with the gain adjuster but that’s not always an option. Sometimes I want to use the center filter.
« Last Edit: August 14, 2006, 09:58:29 PM by pixjohn » Logged
rljones
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« Reply #17 on: August 14, 2006, 10:49:20 PM »
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This is disturbing to see and hear. I'm still waiting on a Leaf 65, but I'm certainly now going to look very closely.

For those of you with this problem, can you post when you received your backs so we can see if there is a pattern that might imply a bad batch. If the dates are scattered, then it might suggest a more pervasive problem.

Thanks,

Robert
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rethmeier
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« Reply #18 on: August 15, 2006, 04:42:48 PM »
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A quote from a trusted colleague!

" Aptus 75: With the introduction of the 7.2/6.8 micron sensors the color cast problem became much more prominent with symmetrical high-end lenses but also with retrofocal lenses. The "centerfold" problem that came up also (Dalsa sensors, but only in some extreme lighting conditions or with extreme movements, same problem with the Sinar eMotion 75) is a rather nasty one. Both can get cured with an up to come gain calibration tool.
So in the end ALL backs from ALL manufacturers need a calibration/correction in one or the other way.
This is hardly acceptable.
The overall performance of the Leaf backs is still better but this is a personal opinion. I hope that Leaf is correcting the residual problems very soon (Canon 22 MP ante portas) as some of our customers with faulty sensors run crazy where others are absolutely happy campers."

IOW , no back is perfect!

Hopefully the next generation will give us less time in post!
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Willem Rethmeier
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mkravit
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« Reply #19 on: September 10, 2006, 02:37:49 PM »
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A quote from a trusted colleague!

" Aptus 75: With the introduction of the 7.2/6.8 micron sensors the color cast problem became much more prominent with symmetrical high-end lenses but also with retrofocal lenses. The "centerfold" problem that came up also (Dalsa sensors, but only in some extreme lighting conditions or with extreme movements, same problem with the Sinar eMotion 75) is a rather nasty one. Both can get cured with an up to come gain calibration tool.
So in the end ALL backs from ALL manufacturers need a calibration/correction in one or the other way.
This is hardly acceptable.
The overall performance of the Leaf backs is still better but this is a personal opinion. I hope that Leaf is correcting the residual problems very soon (Canon 22 MP ante portas) as some of our customers with faulty sensors run crazy where others are absolutely happy campers."

IOW , no back is perfect!

Hopefully the next generation will give us less time in post!
[a href=\"index.php?act=findpost&pid=73452\"][{POST_SNAPBACK}][/a]

Unfortunately this is an unaccptable situation. I have been waiting almost 6 weeks for a replacement back from Leaf with no firm date as to when the replacement will arrive. In fact, I know two other APtus 75 photographers who have had their backs replaced and are experiencing the same problem with the replacements.

Imagine, 1 out of every 125 or so Aptus 75's have this problem as reported by a reliable source at Leaf! What does this mean for the company? Can they replace all of the backs? Why are they not working overtime to create a firmware solution?

The PC only crowd does not have a solution as the new gain adjustment softaware is Mac only and is barely a work around as it changes the gamma of ther raw file. pretty sad IMO.

These backs cost photographers a lot of money. Is it too much to ask that they work as advertised?
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