What is this?

jayman_1975 · 03-31-2015, 09:14 PM

Can someone please tell me what the heck this blue dot is to the left of the knife block?

Last edited by jayman_1975; 04-05-2016 at 06:49 PM.

Aaron28 · 03-31-2015, 09:16 PM

dust? kinda odd to be a bad pixel....maybe pixel map?

K57XR · 03-31-2015, 09:19 PM

Stuck pixel, maybe? As described here:
https://photographylife.com/dead-vs-stuck-vs-hot-pixels

jayman_1975 · 03-31-2015, 09:21 PM

It shows up at different spots on the wall depending on how far im zoomed in. Would a bad pixel act that way?

tvdtvdtvd · 03-31-2015, 09:25 PM

Does it appear with a different lens on the camera? Do you see any blemish on the lens in question? On the mirror?

jayman_1975 · 03-31-2015, 09:34 PM

happens with two different lenses. ill have a look at the mirror.

Aaron28 · 03-31-2015, 09:37 PM

doesn't the mirror flip up when the shot is taken? wouldn't it only be seen in the viewfinder if it were?

Adam · 03-31-2015, 09:49 PM

To me it really looks like failed pixel mapping, since it's perfectly circular and has a little halo. Does it show up in unprocessed raw files?

rburgoss · 03-31-2015, 10:47 PM

You do not mention what body is producing this, but anyway, it surely looks like a bad (hot) pixel. The halo effect is normally produced by the camera's alogarithms that handle jpeg compression as well as sharpening and contrast alogarithms. This phenomena is most evident on jpeg images (from camera) and if the bad pixel falls within a relatively smooth or even image (the wall in your case).

If shooting raw, the bad pixel will be just white but with no halo or compression artifacts. If your camera has pixel mapping, then a single pixel map course should fix this.

I've seen this happen with my *istD. For piece of mind, no sensor is 100% free of defective pixels. Every sensor (new) will show a fair amount of bad pixels, around 0.03% of them (on a 20 Mpix sensor, the average bad pixel count that should be "mapped out" at quality control, is around 4000!)

After mapping out bad pixels (factory quality control), around 3% on the sensors will produce new bad pixels, but in very small quantities (2-3 bad pixels per year). The pixel mapping in camera is used to deal with this small amount of bad pixels.

jayman_1975 · 04-01-2015, 05:37 AM

Yup. Turned out to be a bad bad/stuck pixel. Did pixel mapping and its gone. It's a k5IIs.

03-31-2015, 09:14 PM	#1
jayman_1975 Veteran Member Join Date: Jun 2014 Posts: 385	What is this? Can someone please tell me what the heck this blue dot is to the left of the knife block? Last edited by jayman_1975; 04-05-2016 at 06:49 PM.

03-31-2015, 09:49 PM	#8
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	To me it really looks like failed pixel mapping, since it's perfectly circular and has a little halo. Does it show up in unprocessed raw files? Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

03-31-2015, 10:47 PM	#9
rburgoss Veteran Member Join Date: May 2008 Location: San Jose, Costa Rica Photos: Gallery \| Albums Posts: 972	You do not mention what body is producing this, but anyway, it surely looks like a bad (hot) pixel. The halo effect is normally produced by the camera's alogarithms that handle jpeg compression as well as sharpening and contrast alogarithms. This phenomena is most evident on jpeg images (from camera) and if the bad pixel falls within a relatively smooth or even image (the wall in your case). If shooting raw, the bad pixel will be just white but with no halo or compression artifacts. If your camera has pixel mapping, then a single pixel map course should fix this. I've seen this happen with my istD. For piece of mind, no sensor is 100% free of defective pixels. Every sensor (new) will show a fair amount of bad pixels, around 0.03% of them (on a 20 Mpix sensor, the average bad pixel count that should be "mapped out" at quality control, is around 4000!) After mapping out bad pixels (factory quality control), around 3% on the sensors will produce new bad pixels, but in very small quantities (2-3 bad pixels per year). The pixel mapping in camera is used to deal with this small amount of bad pixels. Last edited by rburgoss; 03-31-2015 at 10:53 PM.*

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
What is this?	Reptilezz	Pentax K-3 & K-3 II	7	02-06-2014 03:12 AM
What mount is this	Bonavista	Pentax SLR Lens Discussion	9	02-05-2014 12:08 PM
What is This!?	OldNoob	Troubleshooting and Beginner Help	18	11-22-2013 10:06 PM
what hood is this?	pixxie	Pentax Camera and Field Accessories	9	08-12-2013 08:12 AM
What is this called & what is it for?	cheekygeek	Pentax SLR Lens Discussion	11	02-06-2010 02:31 PM

03-31-2015, 09:16 PM	#2
Aaron28 Pentaxian Join Date: Jan 2015 Location: Huntsville, Al Posts: 7,131	dust? kinda odd to be a bad pixel....maybe pixel map?

03-31-2015, 09:19 PM	#3
K57XR Veteran Member Join Date: Feb 2011 Location: Colorado, USA Posts: 830	Stuck pixel, maybe? As described here: https://photographylife.com/dead-vs-stuck-vs-hot-pixels

03-31-2015, 09:21 PM	#4
jayman_1975 Veteran Member Join Date: Jun 2014 Posts: 385 Original Poster	It shows up at different spots on the wall depending on how far im zoomed in. Would a bad pixel act that way?

03-31-2015, 09:25 PM	#5
tvdtvdtvd Veteran Member Join Date: Jan 2010 Posts: 1,665	Does it appear with a different lens on the camera? Do you see any blemish on the lens in question? On the mirror?

03-31-2015, 09:34 PM	#6
jayman_1975 Veteran Member Join Date: Jun 2014 Posts: 385 Original Poster	happens with two different lenses. ill have a look at the mirror.

03-31-2015, 09:37 PM	#7
Aaron28 Pentaxian Join Date: Jan 2015 Location: Huntsville, Al Posts: 7,131	doesn't the mirror flip up when the shot is taken? wouldn't it only be seen in the viewfinder if it were?

04-01-2015, 05:37 AM	#10
jayman_1975 Veteran Member Join Date: Jun 2014 Posts: 385 Original Poster	Yup. Turned out to be a bad bad/stuck pixel. Did pixel mapping and its gone. It's a k5IIs.