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09-07-2008, 04:00 PM   #1
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Dust Alert on K20D

When I go through the "Set-up" menu I can not access the "Dust Alert" function. It is visible in the menu, but is less bright than the other listings. The words "Dust Alert" are actually gray, unlike all the other options which have bright, whilte lettering. When I use the down pad to scroll to it, the "Dust Alert" function is somehow skipped over.

Am I missing something? Does anyone have any suggestions? Thanks.

09-07-2008, 04:51 PM   #2
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Thanks, but I found this thread which explains this peculiar aspect of the K20 and answers my question. I had an A lens on, and for some reason the Dust Alert function will not work with an A lens on--nothing I can find in manual on this one--go figure.
09-07-2008, 04:55 PM   #3
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QuoteOriginally posted by Jewelltrail Quote
Thanks, but I found this thread which explains this peculiar aspect of the K20 and answers my question. I had an A lens on, and for some reason the Dust Alert function will not work with an A lens on--nothing I can find in manual on this one--go figure.
Dust alert doesn't work in manual focus mode, even with DA/FA lenses. The reason is the dust alert feature focus the camera at infinity to take the test shot.
09-07-2008, 05:16 PM   #4
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It does not work with an A lens on--period. It does not matter what focus mode you are in.

09-07-2008, 07:15 PM   #5
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Thanks to this thread I finally was able to use the Dust Alert and see the image.

My immediate reaction to the result is not printable on a family-friendly forum.
09-07-2008, 07:30 PM   #6
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QuoteOriginally posted by Jewelltrail Quote
It does not work with an A lens on--period. It does not matter what focus mode you are in.
Of course, because the A lenses do not autofocus... But if you use an FA/DA lens, and switch to manual focus, the dust alert is not available "--period" ;-)
09-08-2008, 07:28 AM   #7
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QuoteQuote:
Mike Cash "Thanks to this thread I finally was able to use the Dust Alert and see the image."

Nice--I am so glad to hear the thread brought help to another shooter--the whole point of our forum! One of our members, JLP, does a great job of summarizing Dust Alert's limitations here:

Only partially true . . . there is no functionality with lenses other than of the Autofocus variety. True, with AF lenses, the focus switch needs to be in the AF-S or AF-C position to use the function (not grayed out). With manual focus A or K lenses it is not a selectable option. If you add an AF teleconverter to a manual focus lens, it will work. Given this function is something you would typically access seldom (and typically not while shooting), it shouldn't be a problem to mount an AF lens at a later time.

I have asked Pentax US to verify this (lack) function and they concur. I have asked also they submit it as a 'bug' for correction in future firmware (or at least a manual correction.)
09-08-2008, 11:24 AM   #8
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I managed to scare the crap out of myself after cleaning with the Pentax wand-n-sticky-paper kit. I went outside, pointed the camera up at the sky, and redid the dust alert test to check my results. What I saw was horrible smudges and smears all over the sensor.

Then I noticed that the pattern of the smudges and smears bore a strong resemblance to the clouds in the sky.

Redoing the check with the lens a couple of inches from the white hood of my car revealed that my cleaning had been a complete success. I knew there were a couple of spots from some f16 long-exposure shots I had done recently, but Dust Alert revealed lots and lots of specks that I had no idea were there.

09-08-2008, 11:49 AM   #9
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Mike Cash:
QuoteQuote:
" Redoing the check with the lens a couple of inches from the white hood of my car revealed that my cleaning had been a complete success. I knew there were a couple of spots from some f16 long-exposure shots I had done recently, but Dust Alert revealed lots and lots of specks that I had no idea were there."

Fantastic--it sure is nice when things go right?
09-08-2008, 02:02 PM   #10
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QuoteOriginally posted by Mike Cash Quote
I managed to scare the crap out of myself after cleaning with the Pentax wand-n-sticky-paper kit. I went outside, pointed the camera up at the sky, and redid the dust alert test to check my results. What I saw was horrible smudges and smears all over the sensor.

Then I noticed that the pattern of the smudges and smears bore a strong resemblance to the clouds in the sky.

Redoing the check with the lens a couple of inches from the white hood of my car revealed that my cleaning had been a complete success. I knew there were a couple of spots from some f16 long-exposure shots I had done recently, but Dust Alert revealed lots and lots of specks that I had no idea were there.
I think this is the new "most common problem" with Pentax, replacing the classic "manual lenses don't work on my Pentax - I just get a flashing "F--". I think everyone that has a K20D has made the same mistake. I tried shooting at a (mostly) blank wall, but still caught some furniture in the edges of the frame. Made me think my sensor must have been cracked, or I combed my dog hair into the camera body.
09-18-2008, 09:15 PM   #11
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Dust alert

So if several dust alert shots show nothing (just a plain white square) and I still get a few defuse looking specs on some sky shots what do I check next?

p.s. I can't really magnify the dust alert image beyond one step so I assume the display would show me exaggerated dust particles if it found any.
09-18-2008, 09:39 PM   #12
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QuoteOriginally posted by nirudha Quote
So if several dust alert shots show nothing (just a plain white square) and I still get a few defuse looking specs on some sky shots what do I check next?
There's a fair chance that they're planes, or birds.
Take a few additional photographs , and look to see if the spots are in different locations.
09-19-2008, 09:29 AM   #13
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QuoteOriginally posted by rfortson Quote
I think this is the new "most common problem" with Pentax, replacing the classic "manual lenses don't work on my Pentax - I just get a flashing "F--". I think everyone that has a K20D has made the same mistake. I tried shooting at a (mostly) blank wall, but still caught some furniture in the edges of the frame. Made me think my sensor must have been cracked, or I combed my dog hair into the camera body.
Ditto me with the K200D. I even shot a plain white wall - but it was textured, and it picked that up. As it is, I just don't really trust this any more than shooting the sky at f/22.
09-19-2008, 08:28 PM   #14
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QuoteQuote:
So if several dust alert shots show nothing (just a plain white square) and I still get a few defuse looking specs on some sky shots what do I check next?
I would check into a good rocket blower :-)
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