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09-20-2015, 01:49 PM   #1
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Color artifacts (small dots) on JPEG mode - Pentax K7

Hello Everyone.

I just bough a "new" Pentax K-7. However I realized today that when I shoot in JPEG im getting lots os small colored dots on the picture. When I shoot RAW this doesnt happen.

Here is a 100% increased picture of a hamburguer:





This colored artifacts shows mostly on dark areas.


Anyone has an idea of what it is? Maybe something on the menu??

Thanks!

09-20-2015, 02:08 PM - 1 Like   #2
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Those look like hot pixels (a lot of them!) or slow shutter speed noise. They can be fixed using a mapping profile, but that almost looks like an excessive amount unless this was a very long exposure with NR off.

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09-20-2015, 02:31 PM   #3
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QuoteOriginally posted by rgimenes Quote
When I shoot RAW this doesnt happen.
I think most raw software automatically removes hot pixels, quite successfully. At least, I think thats what it is. Still seems like a lot of them. I think this would only happen if you were running the camera for a long time in live view in warm weather. Or taking lots of video without a break.
09-20-2015, 03:09 PM   #4
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My K-7 sensor was very similar. I just used the mapping function and they were gone.
Take a long exposure with the lens cap on to really see the before and after mapping difference.

09-21-2015, 03:06 PM   #5
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Thanks for the replies, folks.

This was problably a 1 second exposure or something similar. I was using ISO 200 (Highlight correction ON I think) and F5.6. The camera was not running for no more than 2 minutes. I had just turned it on after a day or two without using. So the sensor was not hot at all.

How to I use the mapping? Where is this function?

Thanks!
09-21-2015, 04:24 PM   #6
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Press Menu, hit the right button a lot of times until you are in the Setup (small icon of a wrench) page 4 menu, and it's the first thing on the list.
09-21-2015, 04:49 PM   #7
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I would suggest you do the following:
a) charge battery, leave it outside of camera for some time so it cools down.
b) install latest firmware update to the camera, if you haven't already
c) run the Dust removal action (where the camera shakes the sensor). Turn off camera, 10 min later, run it again. Leave camera off for another 10 min.
d) read your camera's manual (can be found online) about Pixel mapping, and then follow instructions

b) is optional, and with d) you can skip reading the manual and just activate the function from camera's Menu.
c) is also optional, but it can help sometimes.

Here is an informative article about pixels: https://photographylife.com/dead-vs-stuck-vs-hot-pixels
09-21-2015, 05:49 PM   #8
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Thanks, Na Horuk and Just1MoreDave! Really appreciated your help. I will try those steps. =)

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