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07-17-2011, 04:07 AM   #1
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DUST MAPPING IS CLEAN - but still specks on my photos - what's up??

Looking for a bit of quick advice here - I'm out of town traveling and forgot my cleaning kit at home. These annoying specks have been showing up on my photos and my lenses are clean, AND the dust mapping check function on my K-x also shows CLEAN - I can't see anything. That should suggest that my sensor is clean, should it not?? I've attached a few photos for all to see. I will see if I can get a blower somewhere tomorrow and try that - hopefully that works. However if it's not the sensor then I'm not really sure what it could be.


Last edited by slr_neophyte; 12-14-2012 at 08:54 PM.
07-17-2011, 04:16 AM   #2
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You have dust on your sensor, the dust detect feature is worthless, ignor it.
07-17-2011, 05:40 AM   #3
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You need a blower because you have dust on your sensor.
07-17-2011, 05:53 AM   #4
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QuoteOriginally posted by twitch Quote
dust detect feature is worthless
I'll second that. On my K-x, as new, I tried that gadget and I still could see dust on my photos. Got my Giottos out, blew in a few times, dust gone.

07-17-2011, 05:55 AM - 1 Like   #5
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Reclean still dirty.

As for the dust alert it is not useless. It isnt always accurate and really deends on how you use it. I always find that t works best with a clean solid surface that is of one colour. Anything that is rough texture can confuse the function of it. And also running it twice for confirmation is best i think.
07-17-2011, 06:57 PM   #6
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QuoteOriginally posted by epqwerty Quote
Reclean still dirty.

As for the dust alert it is not useless. It isnt always accurate and really deends on how you use it. I always find that t works best with a clean solid surface that is of one colour. Anything that is rough texture can confuse the function of it. And also running it twice for confirmation is best i think.
I second that. it works very well if you have a good target. I use a blank white word processing page on my computer screen, nice and bright white.
07-17-2011, 11:57 PM   #7
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I have had similar problems where the dust detect failed to pick up the dust and a blower did the trick. I used the sky as a test. As there was nothing for the autofocus to focus on I set the lens to infinity and took a photo of the sky. Cleaned the sensor and did a re check, used my PC to do the check for the dust speck.
07-18-2011, 04:57 AM   #8
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QuoteOriginally posted by Elva Quote
I have had similar problems where the dust detect failed to pick up the dust and a blower did the trick. I used the sky as a test. As there was nothing for the autofocus to focus on I set the lens to infinity and took a photo of the sky. Cleaned the sensor and did a re check, used my PC to do the check for the dust speck.
Doesn't it also help to set the Aperture to maximum?

07-18-2011, 02:14 PM   #9
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QuoteOriginally posted by Elva Quote
I have had similar problems where the dust detect failed to pick up the dust and a blower did the trick. I used the sky as a test. As there was nothing for the autofocus to focus on I set the lens to infinity and took a photo of the sky. Cleaned the sensor and did a re check, used my PC to do the check for the dust speck.
I second that. The "sky test" works best because it is a practical image showing the real time result. I usually set my aperture to f13, manual focus to past infinity,set the lens to 50mm and shoot away. Once you have the photo downloaded, it helps to boost the contrast way up to really see the dust (I use Picasa and slide the "shadows" bar all the way up). Just remember, the photo you are looking at is flipped, so if the dust shows on the right upper corner, it's really in the lower left.

Last edited by agsy; 07-18-2011 at 03:02 PM.
07-18-2011, 02:57 PM   #10
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The sky test works great for me, too ... around f11 + at infinity, manual focus.
07-18-2011, 03:16 PM   #11
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Usually for sky test I focus at closest distance, and for wall test I focus at infinity. I also use f22, ISO100, and wave the camera around a bit if it's a long shutter speed. I want to eliminate any possbility of whats in the sky, or what on the wall showing up in my photos. PRoblem is if you focus at infinity at the sky you will focus at what's in the sky (eg birds).

I then import the photo(s), flip it vertically (so if spot is top left in photo, it's top left looking at the sensor with the camera facing me), and then do an auto levels to highlight the spots clearly. Do all this, and even the subtlest spots of dust will be seen and you'll know exactly where they are on the sensor (handy if using Pentax lollipop).
07-18-2011, 03:47 PM   #12
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QuoteOriginally posted by twitch Quote
the dust detect feature is worthless,
pretty much
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