Luminous Landscape Forum
Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: Christoph B. on February 26, 2016, 07:19:19 pm
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So I just noticed something weird. Something that's not really visible under normal conditions and has never shown up until I 'tortured' my raw files in CaptureOne.
Those strange pentagonal shapes show up on my P65+ sensor (always on the same spot) but the sensor itself shows no signs of damage and works without any problems what so ever.
They are not related to the lenses I use, they are the same every time, at every aperture setting and exposure.
Does anyone know what's going on here? Do I need to be worried?
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Could it be reflections from inside the camera body? Has nobody else ever had anything like that appear on his/her images?
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A complete stab in the dark. I can see you used a 120mm lens @ f/16 from the information at the bottom of the image, does this lens have a 5 bladed aperture?
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They look like crystals, possibly on the sensor or between sensor and IR cover. I would consider sending to P1 to have the unit cleaned if the problem gets serious or to the point where you can't shoot without them being in the image.
Pentagon shape, common to many crystals.
Fluid or moisture dried and left the shapes. Just a thought.
Paul C
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A complete stab in the dark. I can see you used a 120mm lens @ f/16 from the information at the bottom of the image, does this lens have a 5 bladed aperture?
I wish - it appears with every lens (80mm, 120mm, 210mm) in every kind of light situation. Studio flashes, location, short and long exposure, ISO50, ISO400 - doesn't make any difference.
Crystals? Hum....well the image I posted is the whole photo, not a crop but the whole frame. So that would have to be a friggin huge crystal... ^^
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Probably not a crystal but a stain of some sort. Or it be a big old crystal.
Have you cleaned the sensor with the Phase One A solution followed by B?
A is more of a soapy (blue) color then you follow it with the B which will remove streaks.
Paul C
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I sincerely hope it is something as simple as a clean or eliminating a light leak
After cleaning if the problem still exists and is repeatable then I would wrap the camera up completely in black cloth just leaving the lens opening and do a couple of shots to see if it is light penetration through the body gaps and being reflected onto the sensor.
Good luck with this fingers crossed :)
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Hi,
Perhaps you shouldn't torture your images in Capture One. CCD stuff is tricky, much dependent on calbration. if you don't see the stuff in your images just don't care.
Or, you can find an explanation, great! Or you can send your back to Phase One for calibration. Or it is something like Paul's suggestions.
Testing a dark shot seems like a great idea.
Best regards
Erik
So I just noticed something weird. Something that's not really visible under normal conditions and has never shown up until I 'tortured' my raw files in CaptureOne.
Those strange pentagonal shapes show up on my P65+ sensor (always on the same spot) but the sensor itself shows no signs of damage and works without any problems what so ever.
They are not related to the lenses I use, they are the same every time, at every aperture setting and exposure.
Does anyone know what's going on here? Do I need to be worried?
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Hi C + B
I have seen this before. It is not your sensor. If the digital back was splashed by any liquid or even tap water which has mineral content in it and not cleaned or wiped off of the glass protection - if left to dry the result will be a tiny doughnut ring.
I concur with Paul. Clean the digital sensor.
Hope this helps. Have a great weekend.
Jeffery
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Hi,
Fingers crossed!
Best regards
Erik
Hi C + B
I have seen this before. It is not your sensor. If the digital back was splashed by any liquid or even tap water which a mineral content in it and not cleaned or wiped off of the glass protection if left to dry the result will be a tiny doughnut ring.
I concur with Paul. Clean the digital sensor.
Hope this helps. Have a great weekend.
Jeffery
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Phew okay... I have already cleaned it before but it's been a month or so - even if I have to send it to P1 for a cleaning because the user before me got some liquid between the sensor and the IR glass it's not the end of the world...
Does anyone know how much P1 charges for a CLA?
edit: I only have the "B" solution (bought a new one and they don't have the "A" any more). I'll ask again the Mamiya/PhaseOne/Leaf forum - maybe they'll know for sure what's up.
@Jeffrey: that would make sense if it was just a small spot, right? But this is pretty big, it has to be at least 5mm and the sensor is absolutely clean as far as i can tell. I'll try cleaning it right now and tomorrow I'll be able to see if there's any change.
edit2: just cleaned the sensor and - no luck, the spots are still visible.
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@C + B. When I saw something similar it was on the front surface of the sensor glass. Perhaps it's best to sent it in for evaluation.
In the meantime perhaps you could shoot an LCC while working / shooting and apply it to your take in Capture One to see if that would clear it up from your photographs?
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Sadly the LCC does nothing to improve the image, the photo I posted already has LCC applied to it.
Does anyone know how much it costs to have the back cleaned / the glass replaced?
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It's strange. I've seen similar patterns and then it's some dirt on the lens ahead of the aperture, and the shape projected on the sensor is in the shape of the aperture. But as you claim it's the same regardless of lens and shoooting aperture it can't be that. But I would double-check, try shoot wide-open (when the aperture should be 100% round) and see if the shape changes.
If it's the full shot we see it looks totally unlike a cover glass problem, and totally alike some lens dirt problem. I'm no camera repair man though so I'm sure there are people that can figure this out.
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As I said it appears on all of my lenses, the 50mm, 80mm, 120mm and 210mm - and at all aperture settings.
I just contacted PhaseOne, they also suspect it's some kind of residue/dirt between the sensor and the glass
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Are you able to shoot without the calibration file embedded or redo the calibration but starting from scratch, this is possible with a Leaf back not sure how this is done with a Phase.
Good luck with the problem.
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Calibration file?
I guess you don't mean the LCC file?
I doubt I'm able to redo the sensor calibration data, that's not something I would feel comfortable to do and I wouldn't even know how to.
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Calibration file?
I guess you don't mean the LCC file?
I doubt I'm able to redo the sensor calibration data, that's not something I would feel comfortable to do and I wouldn't even know how to.
Are you located in the USA? If so I am sure Digital Transitions in NY can help you out.
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Sadly no - I'm in Austria, so no DT for me. But my local dealer is very helpful and nice so we'll see!
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There's calibration data embedded in the back to compensate for various sensor issues. I'm a bit rusty on this, but I think it's basically just flat-field, dead-pixels and ADC linearity. Bad calibration can show up as tiling on the P65+, but I think this is something different.
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Calibration file?
I guess you don't mean the LCC file?
I doubt I'm able to redo the sensor calibration data, that's not something I would feel comfortable to do and I wouldn't even know how to.
Each Phase back, has a unique calibration file that works to help remove things like tiling, but can also help take out other abnormalities. On the IQ backs, I know the dealer can help with replacing the file, not sure if this can be done with the P+ backs. But from looking at the issue, I don't feel this will help.
As Jeffery said, something has gotten under the IR filter that sits on top of the actual sensor and has dried, leaving the crystal like formations.
Phase can remove/replace that filter and clean the actual sensor, and the back should be good as new. Might be a good time to have the back serviced anyway as Phase can run several different checks on the the sensor as they clean it.
Paul C
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Yeah I guess that's the way to go - and I'm just glad the back still works and looks like it's something that's fixable! :)
Good thing I'm currently selling the rest of my analog stuff, that might actually pay for the CLA
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So I just noticed something weird. Something that's not really visible under normal conditions and has never shown up until I 'tortured' my raw files in CaptureOne.
Those strange pentagonal shapes show up on my P65+ sensor (always on the same spot) but the sensor itself shows no signs of damage and works without any problems what so ever.
They are not related to the lenses I use, they are the same every time, at every aperture setting and exposure.
Hi,
If the patterns do not change (get sharper or blurrier) when you change the aperture, then it must be something in the sensor, and requires a service calibration. If there is a difference in sharpness when you vary the aperture, then it is something in front of the sensor itself, casting a sort of shadow (sharper with narrower apertures).
From your description it seems to be sensor calibration related and not something that cleaning could solve. It's a strange pattern for a calibration issue though, I would have guessed it was something that needs cleaning, but that's apparently not the cause.
Cheers,
Bart
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Hi,
If the patterns do not change (get sharper or blurrier) when you change the aperture, then it must be something in the sensor, and requires a service calibration. If there is a difference in sharpness when you vary the aperture, then it is something in front of the sensor itself, casting a sort of shadow (sharper with narrower apertures).
From your description it seems to be sensor calibration related and not something that cleaning could solve. It's a strange pattern for a calibration issue though, I would have guessed it was something that needs cleaning, but that's apparently not the cause.
Cheers,
Bart
I think that applies to smaller individual particles but not a collection of dust/debris/residue which covers a bigger area. It's not such a singular, clear, dark spot but more of a smudge in a pentagonal shape.
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Okay so I went over the files once more and it seems that it is somewhat related to the aperture Setting - it becomes much more visible when you stop down (f8-16) and less visible when you use a bigger aperture (2.8-5.6).
I think it has to be something either between the sensor and the IR filter OR maybe the IR filter itself. Could it be that there's some stress in the IR-glass? Something like stretching and compression in the glass itself?
Anyway I contacted the dealer from whom I bought the back (in EU we have 2 years of warranty on used items) to sort it out. A crumb of comfort.
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1) Have your Phase One Dealer clean the sensor, possibly using the detergent and then the typical cleaner afterwards.
if (1) doesn't work, and I'd ask your dealer to fully test the cleaning before you do, get your dealer to send it to Phase One or take their fix suggestions.
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1. My P1 dealer has already seen the back and didn't see any dirt or smudges or anything else on the surface, it's superclean - even took a loupe to it and didn't find anything out of the ordinary. He cleaned it himself.
2. Phase One already told me and him separately to send it in, I seriously doubt it's something that can be solved by cleaning the sensor over and over again.
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In discussion with my tech at Capture Integration he shared that they'd seen aggressive cleaning / fluid remove some of the IR/UV coating. Maybe your issue?
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I think that would be visible from certain angles, but the surface looks very even and the coating seems intact - but another possibility. I still have to shoot with the back on Monday but the very next day I'll try to send it in.
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Alright so today (after a month! - yikes!) I got the P65+ back from PhaseOne, they did some recalibration (the files look much cleaner than they did before) and exchanged a few bits and pieces.
They also said they replaced the IR-Filter which cost a whopping 990€.
Now the strange shapes have disappeared (mostly, some tiny variations are still here but it's much better. However I did notice that the small scratches that were present before are still there - and some marks also line up with the scratches. But if PhaseOne really did exchange the IR Filter they would have to be gone, right?
I'm asking myself whether they actually replaced the filter or just cleaned the old one and re-used it, thinking it would be alright.
Here's a comparison, left before and right after the service:
edit: according to my PhaseOne dealer those aren't scratches, they are actually minor flaws in the sensor coating - under normal circumstances they aren't visible anyway :)
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edit: according to my PhaseOne dealer those aren't scratches, they are actually minor flaws in the sensor coating - under normal circumstances they aren't visible anyway :)
Hi,
Much better, so it was a(n odd) cleaning(?) issue with some sort of crystal deposit. However, I don't buy the sensor coating story. Maybe they meant sensor cover-glass AR coating?
Sensor chips are usually sealed with (non-replaceable) cover-glass in the same chip-assembly. The IR filter(stack) is a separate (replaceable) component. Maybe the sensor cover-glass (AR coating?) has a few minute scratches, but as you say, it wouldn't show under normal conditions.
Cheers,
Bart
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Yeah I think you're right, he meant the sensor cover glass coating - anyway I'm glad it's sorted out and because I bought the back from a 2nd hand dealer it didnt cost me a cent (well technically not true, I had to postpone a lot of shoots and some were cancelled because of this - but I didn't have to pay anything on top of that).
It seems that those strange artefacts were due to dirt behind the IR-Filter and some calibration-issues. As I said the noise is noticeably reduced.
The only thing that I find a bit annoying is that somehow they changed the standard sharpening preset on the back, which I now have to correct after every shoot until I find out how to change it back to my previous setting ;)
But as I shoot tethered 90% of the time it's no big deal at all.