Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-23-2011, 06:31 PM   #1
Site Supporter




Join Date: Aug 2008
Location: Orange County California
Posts: 101
Dust Alert on K20

I am not sure what to believe. I used the Dust Alert feature on my k20 and it showed this:

https://www.pentaxforums.com/forums/attachments/58-troubleshooting-beginner-help/98150d1311470959-dust-alert-k20-dust.jpg

I couldn't believe the sensor would be so dirty as I take care when changing lenses, use a rocket blower every few month and do a wet cleaning may be once a year.

So I went out and did what I usually do to check for dust and took a photo of the blue sky with F22. (The wires in the photo are for my orientation, so I would know where the dust is.)

This is what it looks like:

https://www.pentaxforums.com/forums/attachments/58-troubleshooting-beginner-help/98151d1311470959-dust-alert-k20-imgp6192.jpg


So do I believe my own eyes or the K20 dust alert feature?

Attached Images
   
07-23-2011, 08:28 PM   #2
Site Supporter




Join Date: Jan 2010
Location: Michigan
Photos: Gallery
Posts: 2,073
Hi, Lenp
Your test shot is too dark, I think, to show up dust
Here is what sensor dust looks like
https://www.box.net/shared/yfeoj3fdi00xtpnbyoed

There is actually another dust spot in the trees but not easily visible.
It seems the dust shadows are only easily visible in a range of luminance on the high side
and then they become invisible when the luminance is overexposed.

I have made a "Dust Hutch" for lens changing, cleaning, neg processing etc
It has made a big improvement to dust problems generally.
The above problem was corrected by gently blowing filtered air upwards to the sensor with the camera face down.
07-23-2011, 10:49 PM   #3
Inactive Account




Join Date: Aug 2008
Location: Michigan, USA
Photos: Gallery | Albums
Posts: 7,485
Well, you've discovered one of the problems with the dust alert. Any movement or real texture in whatever you're aiming the camera at will show, as dust. Wombat may be correct, too dark to see the dust but it usually at f22, will show up pretty black.

https://www.pentaxforums.com/forums/pentax-dslr-camera-articles/121739-those-...ml#post1259109

07-24-2011, 01:20 AM   #4
Site Supporter
BakDinitzen's Avatar

Join Date: Feb 2011
Location: Danmark
Photos: Gallery | Albums
Posts: 68
Hi lenp,
encountered same thing. Try point your camera at the white ceiling. Think it helps!

07-24-2011, 07:40 AM   #5
Site Supporter




Join Date: Aug 2008
Location: Orange County California
Posts: 101
Original Poster
Thanks everyone. After panicking and posting my message, I went to the manual and read how to use the dust alert function correctly. I was not pointing at a white surface when I did it the first time. I just did it again, correctly this time, and the sensor is clean. I also reshot the sky at f22 and did find one small speck (it is visible in the top third of the photo in the middle).

Lesson learned: read the manual... But I am relieved.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
dust, feature, k20, pentax help, photo
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pentax K-7 Dust Alert and Dust Removal Functions brosen Pentax DSLR Discussion 9 02-09-2016 04:43 AM
K7 dust alert failing me? Keebler Pentax DSLR Discussion 2 03-15-2011 09:46 AM
Dust Alert calculator01 Troubleshooting and Beginner Help 12 01-27-2011 11:45 PM
Dust Alert chris9486 Pentax DSLR Discussion 3 01-24-2010 04:19 AM
To Turn on Dust Alert rustynail925 Troubleshooting and Beginner Help 7 12-19-2009 11:16 AM



All times are GMT -7. The time now is 07:29 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top