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10-24-2009, 08:44 AM   #1
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Pentax K-7 Dust Alert and Dust Removal Functions

Please I need some advice while performing the Dust Alert function, I am using the smc PENTAX DA 21mm F3.2 AL Limited lens with the camera to execute the test, sometimes I get a 100% clean screen and sometimes one with a lot of dust ????

Then, I will proceed and execute the Dust Removal function and it will be a little bit cleaner but not 100%, then once I get a 100% clean sensor (after 2 or 3 cycles), doing the test immediately again, there will be a lot of dust on the sensor again.

I am confused on how to use this function, please could you provide some guidance on how to use it ?, do I have to have the lens cap on it ?, base on the manual I have to have only Pentax DA lenses mounted, what else I should do in order to get reliable and consistent results, thanks

10-24-2009, 08:52 AM   #2
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You have to be pointing the camera at a plain, untextured surface (the sky works great) when you perform the Dust Alert, or the firmware may interpret stuff it sees in the scene as dust on the sensor.
10-24-2009, 09:40 AM   #3
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Thanks Marc, question, if I leave the Lens Cap on that will work ?, or it has to be a white surface with light ?
10-24-2009, 10:34 AM   #4
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I've never tried with lens cap on, but go ahead and tell us how it goes!

10-26-2009, 06:31 AM   #5
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QuoteOriginally posted by brosen Quote
it has to be a white surface with light ?
In my experience the above gives the best (most accurate) result.
10-26-2009, 06:58 AM   #6
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Cap on does not work. it needs light, and a small aperture to show the dust.
Sometimes I just take a picture of the sky (preferably an even area with no clouds), and I spot much better the dust than the camera does.
10-26-2009, 12:01 PM   #7
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As a side issue for the dust alert feature - I accidentally discovered that if you point the camera at (say) a tree with bare branches while using the dust alert feature on a K20, you'll get a very interesting black and white image, and if you transfer your pictures that day using a card reader - there's a file named "dust" with that image. Can be sort-of cool, but not enough that I've tried it with the K-7.
02-02-2016, 04:36 AM   #8
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I have always in the past with digital cameras, "before we had dust reference built into our cameras" I would manually check for dust by simply taking a f22 picture. I use f22 and take a picture of a bright white wall. At f22 any dust on the ccd will show up in a real-time picture, as either a dust line and sometimes looking like a oil spot (oil spots I found to be simply dust on the lens). I have also found that any dust on either the inside or outside lens glass will also produce dust on image at high f stops. Dust is really not problematic between f1.4 to f8 normal everyday shooting. Remembering our lenses have dust on them at all times, as it is impossible to avoid dust on the outside lens. For f11 and up f22 I might wipe the lens down between each shot, as f22 will pick up not only dust on the ccd/cmos but also the lens.

02-02-2016, 06:37 PM   #9
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I get good results shooting at my TV when it's in standby mode with no input since the screen stays blue. Best results when using a manual aperture lens and setting it to F22.

I think you can do it with newer DA lenses too but I'm not sure.
02-09-2016, 04:43 AM   #10
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I've learned that by activating the dust removal option at startup and shutdown, my sensor stays remarkably clean! And, I use both my K-50's a lot! I'm also very careful to turn off the camera when changing lenses.... and I NEVER leave the camera body innards exposed any longer than absolutely necessary.
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