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08-07-2016, 04:15 PM   #16
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As for checking on dead pixels, any shot with the lens covered should work fine.

08-07-2016, 11:45 PM   #17
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QuoteOriginally posted by scottyb70 Quote
Hi,

First time using Pentax and trying the AstroTracer with the 15-30 mm lens for 3 minutes @ 15mm ISO 400. If you look in the shadow areas there are alot of hot pixels. Taken on a 80 degree night.Is this common for Pentax?

Here is a link to the file from DropBox.

https://www.dropbox.com/s/go5fuhauhqgs5b1/IMGP0154.DNG?dl=0
Iíve been looking at the example now on my ĒrealĒ computer and itís really an enormous amount of hot pixels, and this is only after 3 minutes of exposure.

What will 10 minutes look like, or 20minutes? (without dark frame subtraction)
08-08-2016, 07:11 AM   #18
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QuoteOriginally posted by Gimbal Quote
Iíve been looking at the example now on my ĒrealĒ computer and itís really an enormous amount of hot pixels, and this is only after 3 minutes of exposure.

What will 10 minutes look like, or 20minutes? (without dark frame subtraction)
Agreed. I just downloaded this and its a huge mess. However, I don't think this is typical for long exposure with this camera and would suggest the OP get it repaired. Zooming into 100% looks bad but seeing the problem at 200% is shocking.
08-08-2016, 10:14 AM   #19
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QuoteOriginally posted by bwDraco Quote
You might want to try running Pixel Mapping in the settings menu. This checks the sensor for defective pixels so that the camera can compensate for them. It won't completely address the problem (and may have no effect on RAW output) but it will help get rid of the more prominent hot pixels (the camera will interpolate around the bad pixels instead).

A more advanced approach is to take a dark frame yourself (long exposure, lens cap on, viewfinder covered to block stray light) and use it in post to correct for the defective pixels. RawTherapee supports loading a dark frame for this purpose.

Draco
Pixel Mapping is a great idea. And I wonder if the trick would be to do it when the camera is hot. Pixel mapping on a cold camera might not catch "defective" bright spots that only occur at elevated temperatures.

Likewise, the advanced manual DFS approach might get best results by collecting a series of dark frames at different temperatures and then looking at the camera temperature in the EXIF to pick the correct dark frame.

08-08-2016, 10:37 AM   #20
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QuoteOriginally posted by scottyb70 Quote
Hi,

First time using Pentax and trying the AstroTracer with the 15-30 mm lens for 3 minutes @ 15mm ISO 400. If you look in the shadow areas there are alot of hot pixels. Taken on a 80 degree night.Is this common for Pentax?

Here is a link to the file from DropBox.

https://www.dropbox.com/s/go5fuhauhqgs5b1/IMGP0154.DNG?dl=0
The Nikon D800 series uses the same sensor from Sony. One of the issues with this sensor is the need for long exposure noise removal. It is not limited to the Pentax K-1, but rather is endemic on this type of sensor. Ironically, these sensors excel at capturing a great deal of data in low light conditions. Go figure.

Michael
08-08-2016, 02:02 PM   #21
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QuoteOriginally posted by MJSfoto1956 Quote
The Nikon D800 series uses the same sensor from Sony. One of the issues with this sensor is the need for long exposure noise removal. It is not limited to the Pentax K-1, but rather is endemic on this type of sensor. Ironically, these sensors excel at capturing a great deal of data in low light conditions. Go figure.

Michael
But when they found the same spots on the new D810, Nikon immediately launched a callback (Service Advisory) of said body for some kind of servicing. As I understand it this was not a perfect fix but it did improve the performance.

So one question is, are we seeing the improved performance here, or the before-service-performance?
08-12-2016, 02:19 PM   #22
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So is this an issue for all k-1 users? Or this particular body? Reason I'm asking is i want to buy k-1 in near future, and one of the attractions was the ASTRO tracer and full frame low light capabilities for ASTRO photography. If this issue is wide spread that would really make me doubt it's the right model for me.
08-12-2016, 04:34 PM   #23
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I used my Pentax K-1 for some Astroshots and didn't notice any Hot-Pixels (but i wasn't really searching).
Notice: I turned the Noisereduction on, so it takes another 3min shot after the 3min exposure is done, to extract noise! I am happy with my K-1 and the Astrotracer.

Here's a link to my Astroshots, if somebody wants to see them: https://www.flickr.com/photos/interspieder/

08-12-2016, 05:11 PM   #24
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QuoteOriginally posted by Interspieder Quote
I used my Pentax K-1 for some Astroshots and didn't notice any Hot-Pixels (but i wasn't really searching).
Notice: I turned the Noisereduction on, so it takes another 3min shot after the 3min exposure is done, to extract noise! I am happy with my K-1 and the Astrotracer.

Here's a link to my Astroshots, if somebody wants to see them: https://www.flickr.com/photos/interspieder/
Nice images!

I wonder if without NR on image holds up at all. I wanted to switch to FF to get significantly better low light performance compared to my old system. Would love to hear from other K-1 owners.
08-13-2016, 09:43 AM   #25
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Didn't have any issues at all last night without NR on mine (3min exposures at iso400), though I did observe some got pixels in the past. However for my use the resolution is large enough that I never need a 100% crop and under that I've never noticed anything.
08-29-2016, 08:44 AM   #26
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Sony sensor

QuoteOriginally posted by scottyb70 Quote
Hi,

First time using Pentax and trying the AstroTracer with the 15-30 mm lens for 3 minutes @ 15mm ISO 400. If you look in the shadow areas there are alot of hot pixels. Taken on a 80 degree night.Is this common for Pentax?

Here is a link to the file from DropBox.

Dropbox - IMGP0154.DNG
I just read an article that explains that the Sony sensor used on this camera and one of Nikon's cameras has this problem when used for long exposures. I haven't tried my K1 using long exposures at night, but I know what to expect now.
09-21-2016, 07:42 PM - 1 Like   #27
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The White dots, are a form of noise, unique to the Sony 36MP sensor. Was not a problem on the D800, was a problem on the D800e, (fixed on later models silently) Was an immediate problem on the D810 and fixed with a recall. I have used all of said cameras for long exposures at night. The fix for the D810 allows the Nikon to operate up to around 10 minutes before the dots become problematic. With Nikon the dots were throughout the files evenly, with Pentax, they only seem to show in the shadow areas. At least for me.

With Astrotracer, the dots can become a bit more problematic especially after operation over 30 minutes.

My average exposure with Astrotracer is 2 minutes, longest 3.5 shortest 1 minute. Iso ranges from 400 to 3200 average is 1600 at F4.0.

With star trail stacks up to 2 hours, of 2 minute exposures with moonlight adding illumination, the dots are not a problem in the night sky or areas lit by the moon, only in shadows.

With Astrotracer, my skies seem fine but again the darker areas can become problematic, but since they are blurred anyway, I don't worry about it, and just take one exposure for the foreground non traced with LEN on. This takes care of the vast majority of the dots and noise.

Warmer outdoor temps make this issue worse as does high humidity.

In normal use, I limit LEN, as it's wasteful in that you are locked out of the camera for the same time of the previous exposure. This is draining battery life, possibly adding more heat, and for sure can cause you to miss a shot due to changing conditions.

Still overall very impressed with the entire K1 camera and the Astrotracer feature. Image below is a 2 minute exposure on the night sky, at F 3.2 or 4.0, can't remember. Prefer not to have to use F 2.8 as the shallower DOF will be problematic. Sky shot combined with a 1.5 and 1 minute non traced image for the bluff and river. Since I was using a 15mm lens, I should have centered the M Way in the frame, but didn't think of that on that night.

Paul C

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