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11-18-2017, 11:54 PM   #1
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White dots in images taken indoors at exposures 1/25 through 1/10 sec. at f/2.8

Hello everybody,
I have white dots on my raw pictures taken indoors at exposures 1/25 through 1/10 sec. at f/2.8 and ISO 200 - 800. The strange thing, that I cannot notice any dots in my raw pictures taken outdoors at exposures 1/40 through 1/400 sec. and faster at the same f/2.8 and ISO 100 and higher.
I recall, that some K-1 users were posting about white pixels during their astro-photography sessions at long exposures ~30 sec, which was a case of thermal noise. But in my case, indoor exposures 1/25 - 1/10 sec. are much shorter. I have recalibrated my K-1 sensor after I first noticed these white dots. However, they reappeared again, though in different locations. Should I send my camera to Ricoh service center to address this issue, or should I just assume it as normally occurring thermal noise artifacts, that can be mitigated by never setting the exposure slower than 1/40 sec? Please share your thoughts or suggestions.


Last edited by tax; 11-18-2017 at 11:55 PM. Reason: Grammar check
11-19-2017, 12:00 AM   #2
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Are you running the latest firmware? The v1.30 firmware update the issue by patching the noise reduction algorithm.

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11-19-2017, 12:04 AM   #3
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QuoteOriginally posted by Adam Quote
Are you running the latest firmware? The v1.30 firmware update the issue by patching the noise reduction algorithm.
Hello Adam, I have updated my K-1 firmware to V1.43 just before taking these indoor pictures at issue. Should I remap the sensor again then?

Last edited by tax; 11-19-2017 at 12:06 AM. Reason: Extra question
11-19-2017, 12:12 AM   #4
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You can try, but the NR is supposed to work out of the box. Can you post some examples of the issue?


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11-19-2017, 12:14 AM   #5
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QuoteOriginally posted by tax Quote
Please share your thoughts or suggestions.
If there isn't any white dots outdoors and presence of white dots indoors with the same exposure, it could be the presence of an external phenomena that you are not aware of.
Or it could be dust on sensor or lens, or for some reasons your sensor already hits its end of life aging curve and pixels start leaking more and more.
11-19-2017, 12:35 AM   #6
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QuoteOriginally posted by Adam Quote
You can try, but the NR is supposed to work out of the box. Can you post some examples of the issue?
Here are two samples. One of the American flag is taken indoors f/2.8, 1/3 sec., ISO 800 and the arrow shows the white dot. Another sample of a wall is taken outdoors f/2.8, 1/60 sec., ISO 100 and the arrow shows the same spot where the white dot is absent.

---------- Post added 11-19-17 at 01:40 AM ----------

QuoteOriginally posted by biz-engineer Quote
If there isn't any white dots outdoors and presence of white dots indoors with the same exposure, it could be the presence of an external phenomena that you are not aware of.
Or it could be dust on sensor or lens, or for some reasons your sensor already hits its end of life aging curve and pixels start leaking more and more.
Hello biz-engineer, I doubt that my K-1 sensor is reaching its EOL, because I just bought it this spring brand new. Please see my posted samples.
Attached Images
   

Last edited by tax; 11-19-2017 at 12:22 PM. Reason: Grammar correction
11-19-2017, 01:35 AM   #7
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QuoteOriginally posted by tax Quote
I doubt that my K-1 sensor is reaching its EOL
You are right about EOL, might be early life defect. Anyway, I'm surprise to see that, my K1 doesn't have this problem at all, images at low ISO are super clean and free of white spot.
Apparently Nikon had the same kind of issues with Sony sensors, they now source the sensor from Tower Jazz for the D850...

---------- Post added 19-11-17 at 09:41 ----------

The white dots issue, there is nothing to do about it, it's the way the Sony sensor is designed and its implementation to max out dynamic range in DXO charts, some of the pixels might go into avalanche triggered by substrate noise or something, which inevitably lead to a pixel saturation. That means all cameras are affected but most of the time there is enough margin so that the effect is not practically visible. Pentax cameras other than Pentax K1 are not affected.

Last edited by biz-engineer; 11-19-2017 at 01:48 AM.
11-19-2017, 08:58 AM   #8
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Pentax KP is not much different. It has 24MP Sony sensor and every RAW image I have taken so far has a few of these whites after LR conversion. But it is nothing like uncalibrated K-1 sensors which are present in some copies of the camera. The problem with those is that even a mild shadow push causes white dot explosion in dark ares of the frame when dealing with long exposures (~30 seconds and more).

11-19-2017, 09:46 AM   #9
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Strange, haven't noticed anything like this with the K-1, not even at 30s exposures. My little GR has a handful of hot pixels, though, showing up already at 10-20s exposures.
11-19-2017, 11:08 AM   #10
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QuoteOriginally posted by savoche Quote
Strange, haven't noticed anything like this with the K-1
To get a few hot pixels per frame, I need to expose 4 minutes at ISO1600 in total darkness (i.e. K1 with lens cap on in a dark room).

---------- Post added 19-11-17 at 19:09 ----------

QuoteOriginally posted by tax Quote
Please see my posted samples.
What ISO were you using for the indoor photo?
11-19-2017, 11:45 AM   #11
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QuoteOriginally posted by biz-engineer Quote
To get a few hot pixels per frame, I need to expose 4 minutes at ISO1600 in total darkness (i.e. K1 with lens cap on in a dark room).

---------- Post added 19-11-17 at 19:09 ----------


What ISO were you using for the indoor photo?
For indoor shooting like in the American flag sample, I used ISO 200 - 800 and exposures 1/25 - 1/10 sec. Based on the responses to this problem, I see that it may not be relevant to the thermal noise that others experienced in astrophotography, because my exposures are much shorter than 30 - 40 sec. Should I contact Ricoh service center and send my K-1 for repair while it is still under the warranty then?
11-19-2017, 12:11 PM   #12
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If you live in US and end up sending the camera to repairs, I'd highly advise calling after you see that they've received the camera, and speak to a representative about your issue, make sure they know what to look for. They completely ignored my written request (and the little description that you fill out when you send the camera in), and camera returned as it was. I'm gonna have to send it in again later on, and this time I'll make sure they can wake up in the middle of the night and know exactly what's wrong with my camera.
11-19-2017, 12:20 PM   #13
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QuoteOriginally posted by awscreo Quote
If you live in US and end up sending the camera to repairs, I'd highly advise calling after you see that they've received the camera, and speak to a representative about your issue, make sure they know what to look for. They completely ignored my written request (and the little description that you fill out when you send the camera in), and camera returned as it was. I'm gonna have to send it in again later on, and this time I'll make sure they can wake up in the middle of the night and know exactly what's wrong with my camera.
Hello awscreo, I am in the US. Did you send your camera to Precision Camera authorized Ricoh - Pentax Service Facility?
11-19-2017, 05:18 PM   #14
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QuoteOriginally posted by tax Quote
Hello awscreo, I am in the US. Did you send your camera to Precision Camera authorized Ricoh - Pentax Service Facility?
Yup. I had a super messy case unfortunately, mainly because of my extended warranty. If you're still within the first year you should have no issues, but again, I'd advise calling them and making sure they know what to work on. They just run standard tests, and if your issue slips by they won't fix it. They actually lost the sheet I sent with my camera, with problem description, my warranty scans etc, so I had to email them multiple times, and then had a huge delay due to Pentax taking their sweet time approving my extended warranty.
11-20-2017, 06:44 PM   #15
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QuoteOriginally posted by awscreo Quote
Yup. I had a super messy case unfortunately, mainly because of my extended warranty. If you're still within the first year you should have no issues, but again, I'd advise calling them and making sure they know what to work on. They just run standard tests, and if your issue slips by they won't fix it. They actually lost the sheet I sent with my camera, with problem description, my warranty scans etc, so I had to email them multiple times, and then had a huge delay due to Pentax taking their sweet time approving my extended warranty.
Just sent my K-1 to the Precision Camera to fix this white dots issue along with creaking / popping grip and a piece of lint in between the focusing screen and the prism to do items.
Will see how these things are going to be addressed.
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