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08-31-2016, 05:20 AM   #1
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K-1 long exposure hot pixels - anyone not experiencing them?

I've seen multiple threads with people showing their samples of the issue, but I wanted to find out if anyone is not experiencing this issue? Someone that purchased a camera recently maybe? I wanted to get my body today, but I still have doubts since astro is one of the fields I'm interested in.

Threads discussing white noise:
https://www.pentaxforums.com/forums/190-pentax-k-1/327326-k-1-white-dot-issue.html
https://www.pentaxforums.com/forums/169-pentax-full-frame/327365-pentax-k-1-s...trotracer.html

08-31-2016, 06:30 AM - 1 Like   #2
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There is zero "issue" other than an major issue between a very few handful users' ears.
Long exposure means noise. Heat means noise. High ISO means noise. Poor raw development means noise. In all cameras, ever (see Canons "white pixel disaster" Canon 5DSr Noise Issues | Cole Thompson Photography).

There are lots of ways to work with that, dark frame subtraction the one preferred by more professional astro shooters. Go to an astro forum and they will explain everything in detail.
The Types of Images
Dark frame subtraction: Astrophotography Talk Forum Forum: Digital Photography Review
Can we talk seriously about flat/dark/bias frames? - DSLR & Digital Camera Astro Imaging & Processing - Cloudy Nights

If you expect to see no noise at high temperature, long times, high ISO, poorly developed, no DFS done, don't buy a camera.

If you see a fool telling you camera A exhibits less noise than camera B, ask for a raw file proof of the claim, done with the exact same temperature, subject, settings. A liar will only feed you with worthless JPGs or other incomparable data.
08-31-2016, 06:42 AM   #3
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QuoteOriginally posted by beholder3 Quote
There is zero "issue" other than an major issue between a very few handful users' ears.
Long exposure means noise. Heat means noise. High ISO means noise. Poor raw development means noise. In all cameras, ever (see Canons "white pixel disaster" Canon 5DSr Noise Issues | Cole Thompson Photography).

There are lots of ways to work with that, dark frame subtraction the one preferred by more professional astro shooters. Go to an astro forum and they will explain everything in detail.
The Types of Images
Dark frame subtraction: Astrophotography Talk Forum Forum: Digital Photography Review
Can we talk seriously about flat/dark/bias frames? - DSLR & Digital Camera Astro Imaging & Processing - Cloudy Nights

If you expect to see no noise at high temperature, long times, high ISO, poorly developed, no DFS done, don't buy a camera.

If you see a fool telling you camera A exhibits less noise than camera B, ask for a raw file proof of the claim, done with the exact same temperature, subject, settings. A liar will only feed you with worthless JPGs or other incomparable data.
I think some of those posters did pretty in-depth analysis in those 2 posts, especially if you read through and follow their conversations with one another. I have no bone in the issue other than I'm planning to buy a camera, and I wonder if there's an issue with it. I believe there's a raw attached in the very first post in the second thread, and multiple people shared 100% crops from their raws. Some sent the camera to Ricoh as they said it's not a normal behavior. I'm not sure why they'd lie about the issue, they aren't selling other maker's bodies, it just seems like understandable frustration of people that have purchased a top of the line body and are running into technical issues.
08-31-2016, 07:05 AM   #4
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08-31-2016, 07:05 AM   #5
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Let's start a meta thread about threads about the white dot issue... let's blow this totally out of proportion by all means
08-31-2016, 07:16 AM   #6
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QuoteOriginally posted by beholder3 Quote
There is zero "issue" other than an major issue between a very few handful users' ears.
Long exposure means noise. Heat means noise. High ISO means noise. Poor raw development means noise. In all cameras, ever (see Canons "white pixel disaster" Canon 5DSr Noise Issues | Cole Thompson Photography).

There are lots of ways to work with that, dark frame subtraction the one preferred by more professional astro shooters. Go to an astro forum and they will explain everything in detail.
The Types of Images
Dark frame subtraction: Astrophotography Talk Forum Forum: Digital Photography Review
Can we talk seriously about flat/dark/bias frames? - DSLR & Digital Camera Astro Imaging & Processing - Cloudy Nights

If you expect to see no noise at high temperature, long times, high ISO, poorly developed, no DFS done, don't buy a camera.

If you see a fool telling you camera A exhibits less noise than camera B, ask for a raw file proof of the claim, done with the exact same temperature, subject, settings. A liar will only feed you with worthless JPGs or other incomparable data.
We all know that, but this is a new kind of noise not seen by Pentax users before. Nikon users and Sony users have already experienced them, Nikon recalled their D810 for a fix that improved the performance (or masked the problem). Sony users have to live with it (I believe) and my guess is that we have to do the same.

But pretending itís the same thing that has always been is counterproductive, itís not the same thing. Lightroom (at least the version I have) cannot handle it, it does however handle normal hot and dead pixels. Other measures have to be taken to deal with it, but at least there are other measures that do work.
08-31-2016, 07:20 AM   #7
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Nobody so far has written anything which would suggest they know what they are doing or there is any "technical issue". There is very normal noise.

I am happy to see the funny claims to be proven with a set of fully comparable raws from a number of 36 Mpx+ cameras showing there is something really unusual. But that has been avoided at all cost so far by the users making the claim even though that would be an effort of only a couple of minutes. Quite telling.

On the other hand the sensor noise DB linked above shows the K-1 outperforms the D810, 5DIII, 5DSR. A7R2 by quite some margin at the relevant 300 sec exposures - with them all showing quite some noise.
08-31-2016, 07:24 AM   #8
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Yea, look, beholder3 IS right about noise in cases of long exposure, high ISO and high temperatures. However, Sony 36MP chip is the culprit in this cake. I saw it with my Nikons. Same thing with K-1. Does not require super duper skills to see the relation. Sony cooks the RAW file with A7R (same chip), does filtering on it and then performs lossy compression on top of that but Nikons did show the issue which resulted in service call for D810 bodies. So why did Nikon do such a thing is there were zero issues? Yeez.

08-31-2016, 07:32 AM   #9
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QuoteOriginally posted by awscreo Quote
I wanted to get my body today, but I still have doubts since astro is one of the fields I'm interested in.
If the white dot behavior is a deal-breaker for you, it may be best to defer your purchase or consider another brand. It may well be that only some bodies are affected, but that seems highly unlikely. It may be that the behavior is addressable through a future firmware update, but I would not hold my breath.* As for those who have been vocal on the matter and the promotion of other brands, I agree, though it might be good to note that for several of those users the K-1 is only the most recent of a string of cameras from all makers, none of which have delivered to their satisfaction.

BTW, the comments regarding dark frame subtraction and noise and astro work flow are quite accurate. There is no camera available at any price from any brand that will provide beautiful, noise-free astro shots straight out of the box. Some may do better than others, but it is all a matter of degree.** All require application of technique to deal with noise, time, and the rotation of the earth.


Steve

(...not an expert on that style of shooting, but am currently spinning up on integrating wide-field astro into landscapes...the tech can be very involved...)

* Any fix requires: 1) a consistent characterization of the problem, 2) a compelling marketing rational, 3) the firmware/hardware means to implement.

** Expecting impeccable noise behavior from current generation high pixel density sensors at the limit of their performance specification is a long chase down a deep rabbit hole. Better luck might be had with medium format (e.g. 645Z) or FF at 24 Mpixels and below. At the lower resolutions, stitching is your friend.
08-31-2016, 08:04 AM   #10
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QuoteOriginally posted by D1N0 Quote
Let's start a meta thread about threads about the white dot issue... let's blow this totally out of proportion by all means
I agree. The so-called "issue" seems to be elusive except for a fairly specific use case for which the work-arounds are part of long-established practice among astrophotographers.

QuoteOriginally posted by beholder3 Quote
Nobody so far has written anything which would suggest they know what they are doing or there is any "technical issue".
Sadly, I tend to agree. A few of the example photos have alarmed me, but over all I have been puzzled as to what the various posts were supposed to illustrate. I was particularly puzzled by the example using pixel-shift. The gist seems to be that there is a strong belief by some that the white dots are "exactly" (intentional quote) the same issue that was present on the Nikon D800/D810 which Nikon addressed with a combination of service center work and firmware update. From what I understand, that fix involved low-level noise reduction applied by the image processor.* Sony is assumed to use a similar approach. The frustration among those with the problem is the perception that Pentax "should" have been aware of this pitfall and "should" have implemented a similar fix and "should" have issued a general recall once the "issue" surfaced. Perhaps they should have and perhaps they will.

It will be interesting to see how this pans out. My suggestion to those who are most severely affected is to start a "report it here" thread similar to the one that was done for the runaway mirror problem that was common on early run K-3 bodies. That would provide a common location for reportage, though the OP would have to monitor the thread and update the count information.

For reference on how this is done: https://www.pentaxforums.com/forums/172-pentax-k-3/254464-k3-crazy-mirror-sic...ours-here.html


Steve

* It should be noted that the Nikon documentation cautions that the "fix" is not fully dependable and that they continue to recommend in-body background subtraction for long exposures.

Last edited by stevebrot; 09-01-2016 at 06:34 AM. Reason: spelling correction
08-31-2016, 11:46 AM   #11
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My K1 does not show ANY of what's been described as white dots, the only white dots I have are from stars in the sky and it is proven because if I increase the exposure time , star trials appear and no, sorry, I can't see white dots. I don't know who started to propagate this story about "white dots issue, but most of the people who seems to take it seriously are the ones who don't have the camera. Actually, I'm still wondering if those "white dots" are a joke , because , yes, if I do long exposure of the night sky , every star makes a white dot (with astrotracer ON).
08-31-2016, 01:06 PM   #12
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QuoteOriginally posted by biz-engineer Quote
I don't know who started to propagate this story about "white dots issue
It started with a comment by by user Paul2660 on 5 August that was picked up by user Gimbal who started the first thread on 6 August.

https://www.pentaxforums.com/forums/190-pentax-k-1/327326-k-1-white-dot-issue.html

Also on 6 August, user scottyb70 started a thread describing a similar experience:

https://www.pentaxforums.com/forums/169-pentax-full-frame/327365-pentax-k-1-s...trotracer.html

It started with a blog post by a person who is also a forum member that was picked up by the rumor site followed by two initial threads her on PF.

Two weeks later Paul2660 posted his findings to his blog. Here is a link to the blog post:

Pentax K1 White Dot Issue on Longer Exposures–Same as the other cameras using the Sony 36MP chip @ Photos Of Arkansas

The examples are pretty compelling for the images from that user's camera. The blog post was picked up by the rumor site and a few days after that by RiceHigh.


Steve

Last edited by stevebrot; 08-31-2016 at 01:42 PM.
08-31-2016, 01:15 PM   #13
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QuoteOriginally posted by stevebrot Quote
Pentax K1 White Dot Issue on Longer Exposures–Same as the other cameras using the Sony 36MP chip @ Photos Of Arkansas The examples are pretty compelling for the images from that user's camera.
Well, that's possible, in that case, it is a problem of testing / QA control by the sensor manufacturer. I don't how could a camera manufacturer test cameras for white dot if it takes a long time it would be very costly.
08-31-2016, 01:35 PM   #14
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QuoteOriginally posted by biz-engineer Quote
Well, that's possible, in that case, it is a problem of testing / QA control by the sensor manufacturer. I don't how could a camera manufacturer test cameras for white dot if it takes a long time it would be very costly.
If a testing issue, it was a failure of engineering design testing and not a matter of units being outside manufacturing control specs (just my opinion...). It is apparent that Nikon was caught unaware on the D800 and a little short on the D810. Whether Ricoh got caught in a similar issue as with the D810 is hard to say...too many assumptions and virtually no hard data.

As for how to test...sub-assemblies can be pulled at random (statistical sampling) for dark-frame testing with automated evaluation of pixel artifact.


Steve

Last edited by stevebrot; 08-31-2016 at 01:41 PM.
08-31-2016, 09:35 PM   #15
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I dont get the aggression of some. Isn't forum suppose to be a place where you'd share an issue, or ask a question? Can't all be praise and high fives. At least not in my understanding of online communities, but its only my opinion. I already placed an order for my K-1, ill see if issues are there on a fresh batch of cameras (seller told me they've just arrived to their warehouse few days ago). Hope my first experience with a Pentax system will be a happy one)

Last edited by awscreo; 08-31-2016 at 09:43 PM.
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