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12-22-2017, 09:52 PM   #31
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Your white dot problem (illustrated by MJKoski) appears to be "dark noise" and I don't think any "calibration" is going to address it (unless there's an adjustment for noise reduction downstream). It could be the sensor or the amplifier which reads the sensor before that information is digitized (not sure if that would be integral to the sensor or a separate component). It's random noise common to a bad sensor, amplifier, or some type of electrical interference (any high power radio/cell/television transmission or other electrical equipment nearby?) and appears when image gain is increased at higher ISOs. It could just be a noisy sensor.

The cure will most likely lead to the replacement of the offending component. Your long exposure/high ISO/dark background is a good test to see if the problem is remedied. You can also look at the liveview presentation with a high ISO and low lighting to get an idea of how much noise is present (don't be alarmed, some noise is normal).


Last edited by Bob 256; 12-22-2017 at 09:58 PM.
12-23-2017, 01:15 PM   #32
tax
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QuoteOriginally posted by Bob 256 Quote
Your white dot problem (illustrated by MJKoski) appears to be "dark noise" and I don't think any "calibration" is going to address it (unless there's an adjustment for noise reduction downstream). It could be the sensor or the amplifier which reads the sensor before that information is digitized (not sure if that would be integral to the sensor or a separate component). It's random noise common to a bad sensor, amplifier, or some type of electrical interference (any high power radio/cell/television transmission or other electrical equipment nearby?) and appears when image gain is increased at higher ISOs. It could just be a noisy sensor.

The cure will most likely lead to the replacement of the offending component. Your long exposure/high ISO/dark background is a good test to see if the problem is remedied. You can also look at the liveview presentation with a high ISO and low lighting to get an idea of how much noise is present (don't be alarmed, some noise is normal).
Hello Bob 256, I never thought it was related to sensor calibration in the first place. It is clearly a sensor issue. I was expecting that Precision Camera would replace my K-1 sensor from the get go, but they chose just to "recalibrate" it. After I received my camera, I ran some tests but did not notice those dreaded white dots at first. I though that the problem was finally fixed. A few days later I saw them again in raw images taken indoors starting at ISO 800 and above. I precisely mapped these white dots in my test raw pictures using a coordinate grid. To my dismay, the same white dots in precisely same spots appeared in other raw images, and in addition I can see colored dots which did not exist before. I tested my camera in parallel with two other borrowed Pentax K-1 cameras using the same lens and photo shooting conditions. White dots remained in the same spots in all my Pentax K-1 raw images taken indoors and in twilight or dark conditions outdoors, while they were completely absent in raw images taken with two other Pentax K-1 cameras I used as controls. To me it is apparent, that my Pentax K-1 camera has a persistent sensor problem which warrants its complete replacement not just a mere "recalibration." I will elevate this issue up to whatever Precision Camera / Ricoh management level I can get to. I paid good money for this camera and invested in building a collection of lenses around this Pentax platform. I demand quality without any excuses for that matter. Will see how it goes. I will keep you all posted. Merry Christmas to all of you!
12-23-2017, 04:12 PM   #33
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I used five different K-1 bodies and the 1st one was in its own class when it comes to amount of white dots. It was calibrated twice before good results could be obtained. The other four were not absent of dots, but were manageable and even good. Nikon had this same issue with D810 when the model was launched back in 2014. Bodies which were okay according to Nikon's service advisory all had some amount of dots present in long exposures. This is a feature of Sony 36MP chip.
12-23-2017, 04:44 PM   #34
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Since they are in the same locations, it's not a noise problem and is definitely sensor related (or some failure in subtracting the reference background). There could be an adjustment for "black clip" which would mask the dots, but it seems that in your case, it is likely a sensor issue requiring replacement.

Hope you can get this problem fixed to your satisfaction. At least you know how to verify the problem has been fixed.

I did a quick test with my K-1 last night at 3200 and 12800 ISO shooting into a darkened room (just enough light to produce an image in 30 seconds) with no specks visible so that's what you can expect when you get this issue resolved. Too bad, but there are some defects that slip through quality assurance and plague customers like yourself.

Have a good Christmas and let us know how this comes out.

12-23-2017, 06:02 PM   #35
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QuoteOriginally posted by Bob 256 Quote
Since they are in the same locations, it's not a noise problem and is definitely sensor related (or some failure in subtracting the reference background). There could be an adjustment for "black clip" which would mask the dots, but it seems that in your case, it is likely a sensor issue requiring replacement.

Hope you can get this problem fixed to your satisfaction. At least you know how to verify the problem has been fixed.

I did a quick test with my K-1 last night at 3200 and 12800 ISO shooting into a darkened room (just enough light to produce an image in 30 seconds) with no specks visible so that's what you can expect when you get this issue resolved. Too bad, but there are some defects that slip through quality assurance and plague customers like yourself.

Have a good Christmas and let us know how this comes out.
Was the NR on or off? I personally see no white dots with any settings with NR on Auto (basically the dark frame applied), but it doubles my exposure times, and last shoot I really felt it standing in freezing cold snow waiting for 30x25s frames I was hoping to get for stacks at the end of an already hour long outing. With NR off I see white dots in shadows in pretty much anything beyond 20-30s exposure. Precision Camera didn't fix it the first time, I'm planning to send my lens in again soon, probably after holidays.
12-23-2017, 06:21 PM   #36
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I did sensor remapping a dozen of times but it did not change anything. Most of people were complaining about white dots at exposures 30 sec. and longer, mostly during astro-photography sessions. In my case, I noticed them at exposures 1/25 through 1/10 sec. starting at ISO 800 and above, which are normal conditions for shooting indoors without a tripod. The persistence of white dots in the same spots in all raw pictures clearly points to the sensor problem. What really bothers me is that Precision Camera did not address any of the issues I was complaining about in my detailed cover letter to them, besides the white dots. They did not bother to fix my K-1 creaking grip, so I had to fix it by myself when I got the camera back. They did not remove a piece of lint on the right edge of the viewfinder lodged, probably during the camera assembly, between the focusing screen and the prism. And at the same time their Final Repair Ticked stated the following:
1. Image Sensor Repair ???? No explanation what exactly they did to the sensor.
2. Recalibrated Image Sensor - Apparently it did not work!!!
3. Firmware Updated to 1.43 ????? I had already firmware updated to that latest version 1.43 by myself! Are they nuts?
4. Auto Focus Test, Check, Recalibration and Realignment ???? I highly doubt that they did anything at all. I shipped them my camera with its auto focus switched to manual mode and received the camera with its auto focus switched to manual mode. Were they checking its auto focus in manual mode? This is crazy!
5. General Test, Check, Clean and Repair All Functions and Systems ???? Nothing else was broken! Do they really think that their customers are complete idiots?
6. Complete Cleaning (Internal-External) and Optical System ???? The piece of lint in the viewfinder I complained about in writing is still there!!! What exactly did they clean then?
If Ricoh Pentax really wants to put their cameras into professional segment of photography, they probably need to drop Precision Camera as their warranty service provider for good. It is absolutely unacceptable to treat Pentax customers like this. I will continue bug them until they either fix my camera or replace it!
12-23-2017, 06:23 PM   #37
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QuoteOriginally posted by tax Quote
I did sensor remapping a dozen of times but it did not change anything. Most of people were complaining about white dots at exposures 30 sec. and longer, mostly during astro-photography sessions. In my case, I noticed them at exposures 1/25 through 1/10 sec. starting at ISO 800 and above, which are normal conditions for shooting indoors without a tripod. The persistence of white dots in the same spots in all raw pictures clearly points to the sensor problem. What really bothers me is that Precision Camera did not address any of the issues I was complaining about in my detailed cover letter to them, besides the white dots. They did not bother to fix my K-1 creaking grip, so I had to fix it by myself when I got the camera back. They did not remove a piece of lint on the right edge of the viewfinder lodged, probably during the camera assembly, between the focusing screen and the prism. And at the same time their Final Repair Ticked stated the following:
1. Image Sensor Repair ???? No explanation what exactly they did to the sensor.
2. Recalibrated Image Sensor - Apparently it did not work!!!
3. Firmware Updated to 1.43 ????? I had already firmware updated to that latest version 1.43 by myself! Are they nuts?
4. Auto Focus Test, Check, Recalibration and Realignment ???? I highly doubt that they did anything at all. I shipped them my camera with its auto focus switched to manual mode and received the camera with its auto focus switched to manual mode. Were they checking its auto focus in manual mode? This is crazy!
5. General Test, Check, Clean and Repair All Functions and Systems ???? Nothing else was broken! Do they really think that their customers are complete idiots?
6. Complete Cleaning (Internal-External) and Optical System ???? The piece of lint in the viewfinder I complained about in writing is still there!!! What exactly did they clean then?
If Ricoh Pentax really wants to put their cameras into professional segment of photography, they probably need to drop Precision Camera as their warranty service provider for good. It is absolutely unacceptable to treat Pentax customers like this. I will continue bug them until they either fix my camera or replace it!
It's just protocol check list. They don't explain what they do in detail. And often ignore what you write in the dialog box for problem description (judging from few people's experiences)
12-23-2017, 06:27 PM - 1 Like   #38
tax
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QuoteOriginally posted by awscreo Quote
Was the NR on or off? I personally see no white dots with any settings with NR on Auto (basically the dark frame applied), but it doubles my exposure times, and last shoot I really felt it standing in freezing cold snow waiting for 30x25s frames I was hoping to get for stacks at the end of an already hour long outing. With NR off I see white dots in shadows in pretty much anything beyond 20-30s exposure. Precision Camera didn't fix it the first time, I'm planning to send my lens in again soon, probably after holidays.
It appears that setting NR to auto, on or off did make any difference in my case. If you saw white dots at exposures beyond 20-30 sec., I saw them at much shorter intervals of 1/25 through 1/10 sec. I will let you know when I get my camera back again. My patience with Precision Camera crap is running out.

---------- Post added 12-23-17 at 07:32 PM ----------

QuoteOriginally posted by awscreo Quote
It's just protocol check list. They don't explain what they do in detail. And often ignore what you write in the dialog box for problem description (judging from few people's experiences)
When they receive my camera for the second time, I will call them and make sure that they know my camera problems like the Ten Commandments. I am not going to put up with their crap!

12-23-2017, 10:03 PM   #39
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QuoteOriginally posted by awscreo Quote
Was the NR on or off? I personally see no white dots with any settings with NR on Auto (basically the dark frame applied), but it doubles my exposure times...................
When I did it for my previous post, my K-1 was in AUTO for long exposure noise reduction (and yes, it doubles the exposure time to 1 minute). I just repeated the process at 128000 ISO and long exposure noise reduction off, and still no specks. With AUTO, there may have been some additional noise reduction, but with the LCD image, it wasn't obvious. This is the first low light photography I've done with the K-1 and it's pretty impressive. I can barely see the wall (by eye) which I used as a test shot, but the 30 second f5.6 exposure brings out all the colors and is reasonably sharp and well exposed. In any case, I really thought I'd see more noise than I did. but to answer your question, no, I didn't see any white spots either way.

Addenda: I got to thinking about what you said and went back to a white/black target for testing. With 12800 ISO I did see 2 white pixels in the black target but they are pixel events and could be easily retouched. I then reshot with 51200 ISO at f11 (30s), thinking I would see all kinds of noise, but still only the 2 white pixels and a relatively quiet reproduction of the black area (noise reduction turned OFF in both instances). I'm even more impressed.

Last edited by Bob 256; 12-23-2017 at 10:21 PM.
12-24-2017, 01:42 PM   #40
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QuoteOriginally posted by Bob 256 Quote
When I did it for my previous post, my K-1 was in AUTO for long exposure noise reduction (and yes, it doubles the exposure time to 1 minute). I just repeated the process at 128000 ISO and long exposure noise reduction off, and still no specks. With AUTO, there may have been some additional noise reduction, but with the LCD image, it wasn't obvious. This is the first low light photography I've done with the K-1 and it's pretty impressive. I can barely see the wall (by eye) which I used as a test shot, but the 30 second f5.6 exposure brings out all the colors and is reasonably sharp and well exposed. In any case, I really thought I'd see more noise than I did. but to answer your question, no, I didn't see any white spots either way.

Addenda: I got to thinking about what you said and went back to a white/black target for testing. With 12800 ISO I did see 2 white pixels in the black target but they are pixel events and could be easily retouched. I then reshot with 51200 ISO at f11 (30s), thinking I would see all kinds of noise, but still only the 2 white pixels and a relatively quiet reproduction of the black area (noise reduction turned OFF in both instances). I'm even more impressed.
Could you please confirm, that you see no white dots whatsoever when you shoot in dark or indoors conditions with exposures shorter than 30 sec.
12-24-2017, 03:24 PM   #41
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QuoteOriginally posted by tax Quote
Could you please confirm, that you see no white dots whatsoever when you shoot in dark or indoors conditions with exposures shorter than 30 sec.
I'll have to wait for dark and will try to take some shots tonight and post the results. Last night would have been ideal to shoot some star fields but tonight is going to be overcast. I will find a suitable target nonetheless. I would anticipate seeing a small number of white specks since there are always a few defective pixels in any given sensor (hence the two I observed last night).

Are you seeing these white dots on the LCD when you take the pictures, or is it after (or during) post processing? It occurred to me that folks seeing the white dots may be capturing an underexposed frame and then stretching the noise floor with a post processing tool so that naturally occurring noise is being seen. That would be expected since a lot of gain has already been applied to the image by using a high ISO. The frames I took were observed directly on the LCD (which did show the few individual "stuck" pixels clearly). I would anticipate they would appear very similar if brought up in a program like Photoshop but if I had an inadequate exposure and stretched the blacks (using curves) it could well produce what you're observing (not that I've tried that).
12-24-2017, 07:59 PM   #42
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QuoteOriginally posted by Bob 256 Quote
I'll have to wait for dark and will try to take some shots tonight and post the results. Last night would have been ideal to shoot some star fields but tonight is going to be overcast. I will find a suitable target nonetheless. I would anticipate seeing a small number of white specks since there are always a few defective pixels in any given sensor (hence the two I observed last night).

Are you seeing these white dots on the LCD when you take the pictures, or is it after (or during) post processing? It occurred to me that folks seeing the white dots may be capturing an underexposed frame and then stretching the noise floor with a post processing tool so that naturally occurring noise is being seen. That would be expected since a lot of gain has already been applied to the image by using a high ISO. The frames I took were observed directly on the LCD (which did show the few individual "stuck" pixels clearly). I would anticipate they would appear very similar if brought up in a program like Photoshop but if I had an inadequate exposure and stretched the blacks (using curves) it could well produce what you're observing (not that I've tried that).
Hello Bob 256, I did not bother to verify these white dots on the LCD. I use Darktable and RawTherapee on Linux for my RAW-DNG images post processing. I would agree with your explanation of naturally occurring noise, if not for the fact that the same white bright dots in the same precise spots are visible in my RAW images in both Darktable and RawTherapee applications. I can remove them using hot pixel removal option, but this is not what I paid for when I bough this Pentax camera, especially if these white dots were not found in RAW images taken with two other Pentax K-1 cameras in the same conditions and using the same lens. I just don't accept lemons, and I am not going to make that proverbial lemonade in this situation. I will demand a complete replacement of either the sensor or my entire camera.
12-25-2017, 09:29 AM   #43
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QuoteOriginally posted by tax Quote
Hello Bob 256, I did not bother to verify these white dots on the LCD. I use Darktable and RawTherapee on Linux for my RAW-DNG images post processing. I would agree with your explanation of naturally occurring noise, if not for the fact that the same white bright dots in the same precise spots are visible in my RAW images in both Darktable and RawTherapee applications. I can remove them using hot pixel removal option, but this is not what I paid for when I bough this Pentax camera, especially if these white dots were not found in RAW images taken with two other Pentax K-1 cameras in the same conditions and using the same lens. I just don't accept lemons, and I am not going to make that proverbial lemonade in this situation. I will demand a complete replacement of either the sensor or my entire camera.
Not my intention to have you drink lemonade. I completely understand your frustration and would do the same. Just wanted to be sure it's not a post-processing issue rather than a camera issue but if other cameras on same settings/subject did not exhibit problem, it's camera.

Last night I would have gotten a whole lot of white dots, even with a film camera. We got dumped on with a Christmas eve snow storm and I didn't get any chance to take outdoor shots. I'll try again tonight since there's supposed to be some clearing and a chance for stars maybe.

What were all the settings you used when you got your dot problem? I will attempt to duplicate those when I take a test shot. I know you were using 30s and an ISO of 1600 or above - what aperture? Did your image fill most of the histogram with the exposure you used? Will use converted RAW this time to see if any dots are present.
12-25-2017, 05:54 PM   #44
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QuoteOriginally posted by Bob 256 Quote
Not my intention to have you drink lemonade. I completely understand your frustration and would do the same. Just wanted to be sure it's not a post-processing issue rather than a camera issue but if other cameras on same settings/subject did not exhibit problem, it's camera.

Last night I would have gotten a whole lot of white dots, even with a film camera. We got dumped on with a Christmas eve snow storm and I didn't get any chance to take outdoor shots. I'll try again tonight since there's supposed to be some clearing and a chance for stars maybe.

What were all the settings you used when you got your dot problem? I will attempt to duplicate those when I take a test shot. I know you were using 30s and an ISO of 1600 or above - what aperture? Did your image fill most of the histogram with the exposure you used? Will use converted RAW this time to see if any dots are present.
Hello Bob 256, First time I have noticed white dots while shooting indoors at ISO 800 and above, at exposures 1/25 through 1/10 sec., which is shorter than 30 sec., and aperture starting at f/2.8 and all the way down to f/22. My RAW images are uniformly filling the histogram. I do all my shootings in manual mode and I am carefully selecting proper aperture, exposure and ISO parameters.
12-25-2017, 07:28 PM   #45
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Here are 10 cropped area samples of the same white dot in the same sensor spot at 30 sec. exposure and ISO ranging from 100 to 51200, with appropriate f stops compensating 30 sec. exposure and ISO settings, as shown in the each sample EXIF data. These pictures were taken with a tripod and the light brightness in the room was adjusted to compensate for higher ISO settings and NR was set to off. This bright white dot is present in all pictures in the same sensor spot, that makes it clear that my K-1 sensor has a problem. Multiple sensor remapping procedures did not change anything.
Attached Images
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Last edited by tax; 12-25-2017 at 07:58 PM.
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