What's optimal way to test sensor for dust-like particles

**bkpix** · 11-15-2015, 09:25 PM

No one has mentioned the Dust Alert feature in the K-5 menu. (p4 of the wrench menu.) It sets up the image for you.

Dial it up, point the camera at something reasonably bright and white, and take a photo. It processes the image to amplify any dust issues -- and flips it, so the image is oriented the same way as the camera sensor as you look at it from the front. In other words, if the dust is in the lower right corner of the image, it's in the lower right corner of the sensor, not upper left.

**Tonytee** · 11-15-2015, 10:32 PM

Originally posted by Dabola

Today I read this old thread and many comments about sensor problems in early series of K5. Exiftool tells me that my second hand K5 is produced the 23rd of Oct 2010. Serial number is 38619X. On this list of serial numbers I can see many other menbers of this forum mention stain problems with serial numbers close to mine.

I've not noticed anything. Nor have I made any professional test. What's the optimal way to check my camera for stain(s)? Up in the northern Norway blue heaven is uncommon these days of the year. White paper on the wall, hang up the paper in front of a reading lamp or? Is 35mm 2.4 optimal or? Iso 80? Clean computer screen or software-test?

For me the best and simplest way is take a new sheet of copier paper. Use any lens you wish, hold the paper in front of the lens and take a couple of shots. Then go ahead and transfer the photo onto your computer. If there is dust on the sensor, you will notice small, round spots on the image. If you have a magnifying glass it will help to pick up on the smallest of spots. Good luck and hope this helps.

Tonytee

Dabola · 11-16-2015, 06:58 AM

Thanks to all of you for many good advices. BrianR and SteveBr, you are right;
...The thing you're aiming at doesn't need to be in focus at all - the more you stop down, the more the dust will show up.
...create the sharpest shadow of the dust at the sensor.

bkpix, you've found way to do it; K-5's own tool, Dust Alert feature - by the Set-up menu. I was not aware of this tool. Perhaps because this alternative is grayed out when Manual Focus is selected.

Like you, Tonytee, I held a new sheet of copier paper in front of a reading lamp and made a shot. A picture is taken (saved for 30 minutes). With a magnifying glass I could see the grid of pixels. Repeat this process 2-3 times. (The 1st time I discovered two spots which was not visible the 2nd time). Without the paper the light is too intensive and I got further false spots.

Nice to get verified that the sensor in my second hand K5 is as clean as a child butt - as we say in Norway.
Thanks to this forum! I learn – all the time... Finally; here's a printscreen from the manual:

**BigMackCam** · 11-16-2015, 10:35 AM

Yes, you're right of course

I guess I use the LR6 visualise spots function because I can do it the same way for my K3, K5 and Q7 (and any other camera I may end up with in future)... Plus, it's handy when looking for spots in existing images, then applying the same corrections to a series of similar frames...

11-16-2015, 06:58 AM	#18
Dabola Forum Member Join Date: Jan 2011 Location: Bergen, Norway Posts: 60 Original Poster	Thanks to all of you for many good advices. BrianR and SteveBr, you are right; ...The thing you're aiming at doesn't need to be in focus at all - the more you stop down, the more the dust will show up. ...create the sharpest shadow of the dust at the sensor. bkpix, you've found way to do it; K-5's own tool, Dust Alert feature - by the Set-up menu. I was not aware of this tool. Perhaps because this alternative is grayed out when Manual Focus is selected. Like you, Tonytee, I held a new sheet of copier paper in front of a reading lamp and made a shot. A picture is taken (saved for 30 minutes). With a magnifying glass I could see the grid of pixels. Repeat this process 2-3 times. (The 1st time I discovered two spots which was not visible the 2nd time). Without the paper the light is too intensive and I got further false spots. Nice to get verified that the sensor in my second hand K5 is as clean as a child butt - as we say in Norway. Thanks to this forum! I learn – all the time... Finally; here's a printscreen from the manual: Attached Images Last edited by Dabola; 11-16-2015 at 09:06 AM.

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11-15-2015, 09:25 PM	#16
bkpix Site Supporter Join Date: Feb 2010 Location: Creswell, Oregon Photos: Albums Posts: 568	No one has mentioned the Dust Alert feature in the K-5 menu. (p4 of the wrench menu.) It sets up the image for you. Dial it up, point the camera at something reasonably bright and white, and take a photo. It processes the image to amplify any dust issues -- and flips it, so the image is oriented the same way as the camera sensor as you look at it from the front. In other words, if the dust is in the lower right corner of the image, it's in the lower right corner of the sensor, not upper left.

11-15-2015, 10:32 PM	#17
Tonytee Loyal Site Supporter Join Date: Jul 2012 Photos: Gallery \| Albums Posts: 21,457	Originally posted by Dabola Today I read this old thread and many comments about sensor problems in early series of K5. Exiftool tells me that my second hand K5 is produced the 23rd of Oct 2010. Serial number is 38619X. On this list of serial numbers I can see many other menbers of this forum mention stain problems with serial numbers close to mine. I've not noticed anything. Nor have I made any professional test. What's the optimal way to check my camera for stain(s)? Up in the northern Norway blue heaven is uncommon these days of the year. White paper on the wall, hang up the paper in front of a reading lamp or? Is 35mm 2.4 optimal or? Iso 80? Clean computer screen or software-test? For me the best and simplest way is take a new sheet of copier paper. Use any lens you wish, hold the paper in front of the lens and take a couple of shots. Then go ahead and transfer the photo onto your computer. If there is dust on the sensor, you will notice small, round spots on the image. If you have a magnifying glass it will help to pick up on the smallest of spots. Good luck and hope this helps. Tonytee

11-16-2015, 10:35 AM	#19
BigMackCam Digitiser of Film Join Date: Mar 2010 Location: North East of England Posts: 20,670	Yes, you're right of course I guess I use the LR6 visualise spots function because I can do it the same way for my K3, K5 and Q7 (and any other camera I may end up with in future)... Plus, it's handy when looking for spots in existing images, then applying the same corrections to a series of similar frames...