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Forum: Pentax K-1 & K-1 II 09-21-2016, 06:55 PM  
K-1 white dot issue. ?
Posted By Paul2660
Replies: 516
Views: 56,796
I find the white dots are much more noticeable with higher ISO's above 400. The longer exposure the more possible and probable they become. Your 1 minute at ISO 1600 may not be as bad as you think however, but it would be something you just need to try. However a 15 minute exposure at 100, might start to show them especially in the shadows.

So far in my astrotracer work, 2 and 3 minute exposures, I do not notice the dots in the sky hardly at all, but again they do show up in the shadows.

If you try pixel shift for 30 seconds at higher ISO's the dots IMO become the worst, won't do that again.

One facet I have noticed, and it's a positive one, is that the dots appear on my K1 only in the dark areas on the longer exposures. Recent example 2 and 3 minutes at 1600, 1200 and 800, (using moonlight for illumination star trail work), the dot only showed up in the shadow/darker areas. This is unlike my Nikon's which got the dots throughout the image.

Long Exposure Noise reduction on my camera removes around 95% to 97% of them, but I mostly don't use it due to the waste of battery life and time. Pentax locks you out of the camera and doesn't run this operation in the background like Canon does.

Remember, Capture One will open any of these problematic files, and remove all of the dots, without any damage to the file, unlike LR or Silkypix or Pentax's software. You need the Pro version of the software.

Paul C
Forum: Pentax K-1 & K-1 II 09-16-2016, 08:36 AM  
K-1 white dot issue. ?
Posted By Paul2660
Replies: 516
Views: 56,796
I was a bit afraid that this would happen. This needs to go back to Japan to be fixed IMO. Sensor calibration is not an easy task.

I hope they will allow it to be sent to Japan.

Paul C
Forum: Pentax K-1 & K-1 II 09-15-2016, 04:30 AM  
K-1 white dot issue. ?
Posted By Paul2660
Replies: 516
Views: 56,796
Hello Banep.

Yes more like 2 seconds on the rocks. The entire exposure was 2 minutes. I use a lantern for illumination when working the M way. On the series I wasn't paying close enough attention to my foreground. Prefer lantern to flashlights for illumination as the former have to white a light for my taste.

Good idea on the crop.

Paul C
Forum: Pentax K-1 & K-1 II 09-14-2016, 12:06 PM  
K-1 white dot issue. ?
Posted By Paul2660
Replies: 516
Views: 56,796
Least some feel I am down on Pentax, trust me I am not.

The k1 has offered some really amazing opportunities, period. The tech they have with GPS and Astrotracer is quite impressive. I have tried all the tricks over the years besides purchase of a D810A. All the cameras I have tried, can't touch the DR you can get with a 2 minute or so shot on the Milky Way. Sure, not NASA grade, but huge improvement over anything else. The stack method can come close but it's a lot more work in post at least to me. This gives you a lot more license to move around, setups etc. The files are amazingly clean and the stars just pop. I use a 15mm understanding that I have attempt to keep the M way centered or I will trail and blur the M Way, but the images just keep impressing me. Hoping to get somewhere out west next year where a 50mm will work as that should work much better with the edges and not trailing.

Here are two quick screen shots. Should have paid a bit more attention to foreground as I let that blow out, but can be fixed in post. 2 minute series. Had some faint clouds that night, but lucky on this shot they were out of main subject.
Forum: Pentax K-1 & K-1 II 09-14-2016, 11:09 AM  
K-1 white dot issue. ?
Posted By Paul2660
Replies: 516
Views: 56,796
Hi Steve,

I am reaching out to Ricoh USA, as normal tech support on this issue did not have any ideas. Sadly, as I had expected, on Pentax, the linkage between tech, corporate, and repair is a total mess. It seems like tech support in US is not even a Ricoh location and may be jobbed out, as they keep referring to "Ricoh" when they talk to me, as if they are not "Ricoh". The repair for Pentax DSLR in the US, is not Ricoh but Precision Camera on the east coast, and personally, from talking to them today, not sure they can do this type of a fix. They seem more break fix type repair, or just dropping in parts etc. Not attempting to re-calibrate a sensor.

I am curious, have been curious from the day I first shot the K1, if my camera was a bit out of calibration as it has a very bad tendency to blow out highlights, as if it's weighted too much to shadows. I expose way to the left with mine in bright situations, but still have to remember to check the histogram and image preview.

Shooting the Nikon version of the sensor, D800, 800e and now D810, they were a bit more seemingly center weighted, but I need to shoot both cameras side by side one day.

Paul C
Forum: Pentax K-1 & K-1 II 09-14-2016, 04:35 AM  
K-1 white dot issue. ?
Posted By Paul2660
Replies: 516
Views: 56,796
Hi Steve,

The answer from Pentax is to use Long Exposure noise reduction. Yes, this does eliminate the vast majority of the dots, but to me this is very very wasteful and does use up your battery 2x as fast.

Paul

---------- Post added 09-14-16 at 04:43 AM ----------



Hi, just saw your posts, in a way I am glad to see you have the dark band, as I have this also in my K1, and it's most distracting with astrotracer shots. Noticed from day one with the astrotracer and told it was a light leak, which as I thought is not the case.

I will try a few 25000 shots to see if the bar is there, assume it will be.

When your camera returns, I would greatly appreciate it if you would let me know if Pentax fixed the problem on yours, as I will need to try and send mine to Pentax USA.

Thanks
Paul C
Forum: Pentax K-1 & K-1 II 09-13-2016, 10:32 AM  
K-1 white dot issue. ?
Posted By Paul2660
Replies: 516
Views: 56,796
My previous crops, when posted really don't show the effect on the LR images, so I tried to show it here.
Forum: Pentax K-1 & K-1 II 09-13-2016, 10:10 AM  
K-1 white dot issue. ?
Posted By Paul2660
Replies: 516
Views: 56,796
It may be that later cameras have a fix on this already, as it does appear some cameras based on posts here don't show the issue.

However it's quite easy to see on my K1, on any long exposre (at night) in areas that have less illumination or are just dark, here you will see the dots, so the problem is NOT the same as the D810 had as the problem on the D810 existed throughout the entire frame. The fix from Nikon did remove all but about 1% or so.

In the to screens shots below, the image on the left is in LR and left is Capture One. The first crop is showing a area of deep shadows and you can clearly see the dots in through out the image. The 2nd crop is from the same shot, but more towards the middle of frame that has been illuminated by moonlight, and there are basically no dots, or at least no where as many as in the darker areas. These are loaded into C1 and LR with just defaults. C1 just has a process that sees the dots are noise and takes them out, LR for some reason does not, even with local noise reduction applied.

These are from approximate 2 minute exposure, ISO 500, F 4.5 from the 15-30mm at 15mm.

Same problem occurs in the startracer function, possibly a bit worse at least from my work. But there it's possible to shoot a follow LEN frame and this removes the vast majority of the dots, but I still would rather not have to waste the extra time and battery for such an exposure.

Paul C
Forum: Pentax K-1 & K-1 II 08-06-2016, 12:39 PM  
K-1 white dot issue. ?
Posted By Paul2660
Replies: 516
Views: 56,796
I love the time it takes to break out a post. You have more time than I do.

We can call it a disagreement.

Net take the camera out, shoot it for a series of long exposures, you will see white dots, how you choose to remove them I guess is up to you. Not using raw for this type of work to me is a mistake to others it may be fine.

I have posted examples from my camera K1 and my older D800e, which showed the exact same issue. Both are in a previous thread, did not want to repost. I would be happy to send you a raw file, showing the issue, send me an email and I will set it up in my dropbox. The problem, issue, whatever someone want to call it was a big enough issue that Nikon recalled the D810 to fix it. The same issue was fixed in the D800e on early cameras, I owned 2, one was clean the earlier was not. On the D800e the fix was not made public as on the D810. My D810 showed it immediately on the first shoot and within 2 weeks, Nikon had recalled all D810's for this issue, which I posted in a previous post with a link to the recall. If the issue/problem etc was not exactly the same as what was seen in both Nikon cameras using the same Sony 36MP chip, I would not have brought to this forum's attention as I felt there might be some photographers using the camera in the same method I am and thus they will see the same problem. I still call it a problem as it was totally fixed with firmware in the Nikon D810.

Not at all trying to slam Pentax as I feel the advantages of the K1 far out weight this type of shortfall.

Paul C

---------- Post added 08-06-16 at 12:40 PM ----------



Yes I will look at that tonight.

Paul C
Forum: Pentax K-1 & K-1 II 08-06-2016, 10:13 AM  
K-1 white dot issue. ?
Posted By Paul2660
Replies: 516
Views: 56,796
I have to say, that I find this post disappointing, as you personally don't know me, or how much time I have spent working on this type of photography. I have put in the time and for star trail photography, this is an issue that your mention of a manual dark frame subtraction won't fix. But needless to say, your points merit a response as I disagree with them.

This issue has been found before years prior and I would have hoped that Pentax would have taken similar steps to address it, which it appears they did not. Depending on your workflow and end result it can become problematic.

Don't really consider myself a noob, but will take it as you will. And for sure it's not "lack of user knowledge" sorry you feel necessary to take that approach. You can go to all the astro forums you want, and this particular issue will not be fixed as it's an issue that is different than traditional noise. I would also ask if you have tired this yourself? I have thousands of exposures and hours of time in stacking with various cameras. Only wanted to point out that this same problem existed in a different brand which uses the same sensor, the other company fixed it.

If you want to go through all the process of taking a dark frame and trying to manually subtract it that is fine. Net, there are plenty of cameras out there, basically all from Canon, Nikon, etc that can take such a exposure without creation of a white dot, which by the way is not that easy to remove even with a true dark frame ( I have tried it) and the white dots don't clean up as well as traditional dark noise, which tend to show up in red, red, or blue dots, which a dark frame subtraction can remove.

I had hoped that the K1 would at least equal the long exposure quality from other cameras I have used, none of which require taking a dark frame and manually removing the noise. again this is mostly for traditional stuck pixels, which are both larger and brighter than the dots. With any modern digital DSLR, you should be able to take a up to a 2 hour long series of stacks, anywhere from 30 seconds to 2 minutes to 3 minutes each and not have the dots, yes you will have noise, but most of that can be removed during the stacking process later on, as the dots will stay in the same place throughout the entire stacking process. The problem comes in when you combine the images.

Working with a intervalometer, you will always have a faint gap between the exposures, and I only know of one tool that will remove these in post, and that is "star tracer". By design it will move the stacked image in a series of controlled blurs, which will combine the gaps into complete trails, and help to give faint trails a brighter look, however this process of movement also moves the dots into dotted trails throughout the image that with a 36MP image will show up. Net, the dots have to be out prior to this final step, and manual dark frame in my experience will not remove them.
The in camera noise reduction, which you seem to feel is also noob feature, works well and in fact more than likely works better than any manual dark frame process, but it defeats the stacking process due to the gaping it creates.

As I already pointed out, Capture One can remove most of this in a raw file, but if you capture in jpg, then it will work on the dots.

Paul C
Forum: Pentax K-1 & K-1 II 08-06-2016, 06:17 AM  
K-1 white dot issue. ?
Posted By Paul2660
Replies: 516
Views: 56,796
Cold temps will definitely make the issue show less prominently. And the longer the individual stack, say up to 1' 30" or 2 minutes, the worse the issue becomes.

If the dots did not look so identical to what Nikon had with the D810, I would have not brought up the issue, but as a night photographer, who stacks, this is a big deal, just as it was with Nikon.

I am not familiar with the previous posters mentioned tests, however if the photographer used the Long exposure noise reduction to "on", the issue will not show for a much longer time frame.

Actually the issue was also in the D800e, but Nikon choose to fix that much more quietly, as early cameras had the problem and later ones did not, per my article. They just somehow forgot the issue with the D810, and got caught sooner, thus did the right thing and fixed it.

D800 Reticulation issues during night photography–white dot problems @ Photos Of Arkansas

The effect is the same, to the letter. Immediately brought back memories of this problem with Nikon, 2012 and 2014 (D800e and D810).

Paul C
Forum: Pentax K-1 & K-1 II 08-06-2016, 04:19 AM  
K-1 white dot issue. ?
Posted By Paul2660
Replies: 516
Views: 56,796
No the faint white dots which show up ip also in areas of non sky per my crop in previous thread are not stars.

They are a form of noise that the chip produces in rather large quantities especially as the chip gets hot.

Capture one software will remove most of them but it's the only raw converter I know of that will. Silky pix and LR cannot remove them.

Paul C
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