K10D and "Hot" Pixels

brewmaster15 · 06-07-2021, 10:36 AM - **1 Like**

Hi all,

I have been using my K10D alot lately and recently noticed a sporadic issue with Hot Pixels. Sometimes I would see some, sometimes not. I understand that these can happen at higher Iso settings but even at these it wasn't consistent but it was getting more frequent. I read that hot pixels can happen at higher ISOs because the pixels heat up.I figured that makes sense, so why aren't I seeing these all the time when I shoot Iso 800 on the K10D? I think I answered it. Its not just that the pixels can heat up.. but if the camera is phyiscally hot it can either cause it or make it worse.

This came about because I was out yesterday taking pics...It was in the 90s. I came in was looking at the images and my images had some pretty bad hot pixels. Which I could not understand why. I got to thinking that yesterday was very hot. So I decided to run an experiment... I took a series of pictures from ISO 100-1600 with the lens cap on and camera was " cold"... room temp normal. I then took my camera out and carried it around a bit. Todays as hot as yesterday... Repeated the experiment.

Both set of exposures showed more hot pixels as the Iso went up which was expected.. but the camera that was "hot" had far more hot pixels. That makes sense if you think about it.

Heres two samples.. straight out of the Camera as Jpgs
Iso 800 cold..

cold K10D 800

Iso 800 Hot

Hot K10D Iso 800

You will need to click on the image and blow it up in Flickr to see the Differences.

Just thought I would share this... I'm sure its not news to some here, but maybe it is to others.

Al

photoptimist · 06-07-2021, 11:01 AM - **2 Likes**

Great example!

In the astro world, this is a well known problem. This kind of noise doubles for every 6° to 8° C in temperature, is proportional to shutter time, and proportional to ISO.

The first line of defense is dark frame subtraction -- taking a second image with identical shutter time and ISO which is then subtracted from the primary image.

The second line of defense is sensor cooling -- hard-core astrophotography cameras often include refrigeration systems to chill the sensor and reduce the noise.

P.S. This physical property of silicon creates one of the disadvantages of mirrorless cameras. MILCs run the sensor at full power all the time to provide a nice viewfinder image but that makes the sensor hot.

**MossyRocks** · 06-07-2021, 02:51 PM - **3 Likes**

Photoptimist beat me to it. Heat results in more noise and is a problem for astro shooting where long high ISO shots are common. That is one of the reasons I love doing astro in a Minnesota winter. The outside chills things down to -20F, there is no humidity in the air, astro dark that starts at about 7PM and ends at 6AM, and when it is that cold here it also likely means there is no wind, so basically perfect astro shooting conditions.

A single dark frame subtraction will improve things but for astro shooting a master dark is usually created for the session which will provide better results as it will do a better job of removing systematic error as many dark frames are averaged together so the truly random portion is driven down leaving mostly the systematic error like hot pixels, dark current, amp glow, etc. which can be better removed leaving more signal in the final image. Then again astro shooters also will stack many light frames to drive down the noise and provide more bits to work with as well as do all sorts of other things.

brewmaster15 · 06-08-2021, 03:24 PM

Thank you Photoptimist and MossyRocks for your comments here and insight. I dont know much about astrophotography shooting wildlife pics mostly.. So I had no clue temp was so important there.. very interesting!
Al

**paulh** · 06-08-2021, 03:46 PM

Does shooting in RAW make a difference? My old *ist D has a ton of hot pixels, but I found that shooting in RAW eliminated the problem. I've no experience doing astro.

06-07-2021, 10:36 AM - 1 Like	#1
brewmaster15 Veteran Member Join Date: Jan 2015 Location: CT Posts: 1,860	K10D and "Hot" Pixels Hi all, I have been using my K10D alot lately and recently noticed a sporadic issue with Hot Pixels. Sometimes I would see some, sometimes not. I understand that these can happen at higher Iso settings but even at these it wasn't consistent but it was getting more frequent. I read that hot pixels can happen at higher ISOs because the pixels heat up.I figured that makes sense, so why aren't I seeing these all the time when I shoot Iso 800 on the K10D? I think I answered it. Its not just that the pixels can heat up.. but if the camera is phyiscally hot it can either cause it or make it worse. This came about because I was out yesterday taking pics...It was in the 90s. I came in was looking at the images and my images had some pretty bad hot pixels. Which I could not understand why. I got to thinking that yesterday was very hot. So I decided to run an experiment... I took a series of pictures from ISO 100-1600 with the lens cap on and camera was " cold"... room temp normal. I then took my camera out and carried it around a bit. Todays as hot as yesterday... Repeated the experiment. Both set of exposures showed more hot pixels as the Iso went up which was expected.. but the camera that was "hot" had far more hot pixels. That makes sense if you think about it. Heres two samples.. straight out of the Camera as Jpgs Iso 800 cold.. cold K10D 800 Iso 800 Hot Hot K10D Iso 800 You will need to click on the image and blow it up in Flickr to see the Differences. Just thought I would share this... I'm sure its not news to some here, but maybe it is to others. Al

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06-07-2021, 11:01 AM - 2 Likes	#2
photoptimist Pentaxian Join Date: Jul 2016 Photos: Albums Posts: 5,128	Great example! In the astro world, this is a well known problem. This kind of noise doubles for every 6° to 8° C in temperature, is proportional to shutter time, and proportional to ISO. The first line of defense is dark frame subtraction -- taking a second image with identical shutter time and ISO which is then subtracted from the primary image. The second line of defense is sensor cooling -- hard-core astrophotography cameras often include refrigeration systems to chill the sensor and reduce the noise. P.S. This physical property of silicon creates one of the disadvantages of mirrorless cameras. MILCs run the sensor at full power all the time to provide a nice viewfinder image but that makes the sensor hot.

06-07-2021, 02:51 PM - 3 Likes	#3
MossyRocks Loyal Site Supporter Join Date: Nov 2017 Location: Minnesota Photos: Gallery \| Albums Posts: 2,982	Photoptimist beat me to it. Heat results in more noise and is a problem for astro shooting where long high ISO shots are common. That is one of the reasons I love doing astro in a Minnesota winter. The outside chills things down to -20F, there is no humidity in the air, astro dark that starts at about 7PM and ends at 6AM, and when it is that cold here it also likely means there is no wind, so basically perfect astro shooting conditions. A single dark frame subtraction will improve things but for astro shooting a master dark is usually created for the session which will provide better results as it will do a better job of removing systematic error as many dark frames are averaged together so the truly random portion is driven down leaving mostly the systematic error like hot pixels, dark current, amp glow, etc. which can be better removed leaving more signal in the final image. Then again astro shooters also will stack many light frames to drive down the noise and provide more bits to work with as well as do all sorts of other things.

06-08-2021, 03:24 PM	#4
brewmaster15 Veteran Member Join Date: Jan 2015 Location: CT Posts: 1,860 Original Poster	Thank you Photoptimist and MossyRocks for your comments here and insight. I dont know much about astrophotography shooting wildlife pics mostly.. So I had no clue temp was so important there.. very interesting! Al

06-08-2021, 03:46 PM	#5
paulh Site Supporter Join Date: Sep 2010 Location: DFW Texas/Ventura County, CA Photos: Gallery \| Albums Posts: 33,308	Does shooting in RAW make a difference? My old *ist D has a ton of hot pixels, but I found that shooting in RAW eliminated the problem. I've no experience doing astro.