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11-15-2010, 03:57 PM   #1
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Please help!! Lens dust or sensor dust?

This picture was shot at f22 (cropped)


I know that the larger black/grey spots are sensor dust and I have removed them (I'm pretty sure). However, what the frig are those white specks around the sun? Is this something wrong with the lens... scratches or dust perhaps?

I don't want to compulsively clean the lens because I know that can do more harm than good. wearing off the coatings and such. However, this strange artifact is rather disturbing and I would like to know if it is normal!

Thank you so much!


Last edited by paperbag846; 11-23-2010 at 10:41 AM.
11-15-2010, 04:16 PM   #2
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Hot pixel?
11-15-2010, 04:18 PM   #3
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f22 will show sensor dust, however it's impossible to say for sure with just one image whether that is sensor dust or dust on the lens, or even an insect that flew into your frame (I've had that a few times and it sure looks like sensor dust).

Shot plain blue sky with a couple of lenses @ f22 and see if that spot turns up in the same position each time. If so it's sensor dust and if so I'd start off addresing it with a Giotto Rocket Blower.
11-15-2010, 04:27 PM   #4
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QuoteOriginally posted by wlachan Quote
Hot
Hot pixel could be it. Would a hot pixel be created by an extremely bright light (aka sun?)

I have the sensor a good blowing and the darker spots went away... so that's good. It's just the white specks I am worried about. As long as it has nothing to do with the lens, I won't worry too much about it. I'm concerned there is something wrong with my new lens .

No other lens I have has shown those white specks (they did show the black ones) but all my other lenses flare up pretty badly shot directly into the sun, so I still can't tell if it is the lens or the sensor.

I'll try pixel mapping for now. Any other ideas?

11-15-2010, 04:34 PM   #5
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Can't be the lens imho. Dust inside lens might be visible with wide angle & f22, but those 2 dots are too sharp to be dust. Hot pixels are rather common with Pentax DSLRs, but since I shoot raw only, the converter will take care of them automatically so they never bother me. Hot pixels will become more visible as the iso gets higher. They are either white, red, green or blue. Take a shot at different iso jpeg with cap on. Since the whole frame will be black, any hot pixels will be visible instantly.
11-15-2010, 04:35 PM   #6
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QuoteOriginally posted by paperbag846 Quote
I'll try pixel mapping for now. Any other ideas?
Sorry I misread your initial post. Yes they look like hot pixels, run the pixel mapping and see if that fixes it.
11-15-2010, 04:49 PM   #7
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QuoteOriginally posted by wlachan Quote
since I shoot raw only, the converter will take care of them automatically so they never bother me.
I shoot raw as well, but apparently lightroom does nothing to help me. It's easy enough to clone out of the keepers, but I just wanted to make sure everything was ok with the lens.

Also, can a pixel be made "hot" with an extremely bright light source, such as the sun? I don't normally have these sorts of artifacts, and a 100W bulb did not bring them out, either.
11-15-2010, 04:56 PM   #8
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That's weird. I use LR2.7 and it removes hotpixels w/o issue. Can you post the jpeg w/o resize?

11-15-2010, 09:25 PM   #9
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Here we are, thanks for the help. You will notice the spots are very small, and all concentrated around the sun.
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