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07-09-2013, 04:28 PM   #1
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"Dust Alert"

Am I missing something or did Pentax get RID of the "Dust Alert" function that was handy on my K-x for pinpointing where the dust was on the sensor before applying the blower?

07-09-2013, 06:19 PM   #2
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Yes, this feature is gone in K-30. However there is an easy test which gives you a good idea where the dust is (see in the comments in the 2 threads below):
https://www.pentaxforums.com/forums/pentax-k-30/195666-dust-alert.html
https://www.pentaxforums.com/forums/pentax-k-30/215388-dust-alert.html
07-09-2013, 08:01 PM   #3
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QuoteOriginally posted by kodai84 Quote
Am I missing something or did Pentax get RID of the "Dust Alert" function that was handy on my K-x for pinpointing where the dust was on the sensor before applying the blower?
Unfortunately it is no more. That's the only thing the K20D had that I miss on the K-30, and I guess I don't miss it that much. If it's not a bright sky to walk outside and shoot, I take a photo of a white screen on the computer (like a blank word processing document) and then look at that. Just remember that the screen is upside down and reversed from looking at the sensor.
07-10-2013, 10:47 AM - 2 Likes   #4
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QuoteOriginally posted by ramseybuckeye Quote
Unfortunately it is no more. That's the only thing the K20D had that I miss on the K-30, and I guess I don't miss it that much. If it's not a bright sky to walk outside and shoot, I take a photo of a white screen on the computer (like a blank word processing document) and then look at that. Just remember that the screen is upside down and reversed from looking at the sensor.
Closing down the aperture as far as it goes, and using as long a focal length as possible will make the dust more visible.

Another better way I found to show even the smallest specs of dust is to remove the lens and take a photo from some distance of a very bright LED torch with its focusing lens removed. The idea is to have a small point source. You need to this in a dimly lit or darkened room. This casts sharp shadows of the dust onto the sensor. Even better if you shoot a number of pictures with the camera pointing in different angles, slighlty offset from facing diectly at the torch, say up to some 30 degrees or so. This apart from dust will also reveal oily smudges, which will appear at different angles of incidence.

I suppose you can do the same with the sun, though for some reason I never tried it. That is remove the lens and point the camera towards the sun and shoot phots, again at various angles. This should pose no risk of burning out anything since there is no lens to concentrate the sun's rays.

For all this it is best to use low ISO and choose the right shutter speed to get a bright grey, but not entirely white image.

07-10-2013, 01:19 PM   #5
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QuoteOriginally posted by lister6520 Quote
Closing down the aperture as far as it goes, and using as long a focal length as possible will make the dust more visible.

Another better way I found to show even the smallest specs of dust is to remove the lens and take a photo from some distance of a very bright LED torch with its focusing lens removed. The idea is to have a small point source. You need to this in a dimly lit or darkened room. This casts sharp shadows of the dust onto the sensor. Even better if you shoot a number of pictures with the camera pointing in different angles, slighlty offset from facing diectly at the torch, say up to some 30 degrees or so. This apart from dust will also reveal oily smudges, which will appear at different angles of incidence.

I suppose you can do the same with the sun, though for some reason I never tried it. That is remove the lens and point the camera towards the sun and shoot phots, again at various angles. This should pose no risk of burning out anything since there is no lens to concentrate the sun's rays.

For all this it is best to use low ISO and choose the right shutter speed to get a bright grey, but not entirely white image.
Good points!
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