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04-10-2007, 07:15 AM   #1
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Dark spot

Decided to check for dust yesterday. Took an out of focus shot at f/22 of the grey overcast sky - and proceeded to pixel-peep. Pretty soon: Ah hah! A dark spot. Gave it the dust-removal shake - still there. Gave it a blow - still there.
Ran a bunch of shots of plain white paper, flash-lit, through a range of apertures. The spot nearly blurs out completely below f/16 and becomes progressively sharper and darker as I approach f/32. Tried another lens, same result. Went back in time through my photos and could see the same spot on anything taken at f/16 or higher when there was a plain background at the spot's location in the frame, going right back to when the camera was new (about 3 months ago).

So I decided to clean the sensor. During this prolonged agonizing endeavour, I came to learn what real dust looks like. Eventually I got things back to dust-free again. But: spot still there.

It's real small, about 4 or 5 pixels or so, sort of ovoid in shape, with perhaps a hint of a ring - kind of like a miniscule sunspot. The way it shows up under different exposure conditions, I'm sure it's something above the actual CCD, but it appears closer than dust. My current theory is that it's a flaw in the low-pass filter, about the size of a pixel or two.

Now if I never shot above f/5.6 I'd likely never notice it. But I quite like small apertures, especially for close-ups, and about 10% of my shots are f/16 or smaller. And now that I know this spot is there, I see it. (OK sometimes I go in and check for it first.) It's at about the lower-left 1/3 intersection in the frame, nearly the worst place for a flaw to be.

That's my dark spot story in excruciating detail. Now to a question: What would you do about this?

This is an example of a little knowledge turning my ignorant bliss into a little irritation.
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04-10-2007, 07:35 AM   #2
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I share your pain.

I have a spot that will not come out either. I took my camera in for a professional cleaning and they showed me an extreme closeup of a before and after. They showed me a small speck that is actually a tiny piece of dust *under* the sensor screen. It can only be seen with extreme cases. That was back in November.

Since then, I have taken many, many great pictures and have put this little thing out of my mind. I know it is there, but also that it is not always evident.

Your speck may be big or small, I don't know. It may be under the screen. How new is the camera? Then, ask yourself if it really shows up all the time, is it worth sending it in for repair.

For me, the answer was no, not now. If something major happens, I will just add that to the list of things to repair at that time.

Jeff


QuoteOriginally posted by dbh Quote
Decided to check for dust yesterday. Took an out of focus shot at f/22 of the grey overcast sky - and proceeded to pixel-peep. Pretty soon: Ah hah! A dark spot. Gave it the dust-removal shake - still there. Gave it a blow - still there.
Ran a bunch of shots of plain white paper, flash-lit, through a range of apertures. The spot nearly blurs out completely below f/16 and becomes progressively sharper and darker as I approach f/32. Tried another lens, same result. Went back in time through my photos and could see the same spot on anything taken at f/16 or higher when there was a plain background at the spot's location in the frame, going right back to when the camera was new (about 3 months ago).

So I decided to clean the sensor. During this prolonged agonizing endeavour, I came to learn what real dust looks like. Eventually I got things back to dust-free again. But: spot still there.

It's real small, about 4 or 5 pixels or so, sort of ovoid in shape, with perhaps a hint of a ring - kind of like a miniscule sunspot. The way it shows up under different exposure conditions, I'm sure it's something above the actual CCD, but it appears closer than dust. My current theory is that it's a flaw in the low-pass filter, about the size of a pixel or two.

Now if I never shot above f/5.6 I'd likely never notice it. But I quite like small apertures, especially for close-ups, and about 10% of my shots are f/16 or smaller. And now that I know this spot is there, I see it. (OK sometimes I go in and check for it first.) It's at about the lower-left 1/3 intersection in the frame, nearly the worst place for a flaw to be.

That's my dark spot story in excruciating detail. Now to a question: What would you do about this?

This is an example of a little knowledge turning my ignorant bliss into a little irritation.
--
dbh - "Always looking for trouble" (my Mom)

Last edited by jsundin; 04-10-2007 at 07:35 AM. Reason: typos
04-10-2007, 07:40 AM   #3
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I'm inclined to say that you should go running and screaming all over town, post numerous forum threads about the issue; detailing the horror of finding the spot, the horror of trying to remove it, the horror of dealing with service, the horror of a possible replacement and finally the horror of an actual replacement. The idiots you had to explain everything too, the nasty bureaucrats that interfered with your satisfaction---in short pour our all the grubby little details in the most shrill whine you can type. Involve as many people as possible, stir the pot and really let the indignation fly! Finally, you could post an example photo, get the forums most esteemed pixel peepers approval that you do, indeed have a life-threatening situation

or call Pentax Service and see what can actually and meaningfully and rapidly be done to 'fix' the problem.
04-10-2007, 08:54 AM   #4
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QuoteOriginally posted by jsundin Quote
I have a spot that will not come out either. I took my camera in for a professional cleaning and they showed me an extreme closeup of a before and after. They showed me a small speck that is actually a tiny piece of dust *under* the sensor screen. It can only be seen with extreme cases. That was back in November.

Since then, I have taken many, many great pictures and have put this little thing out of my mind. I know it is there, but also that it is not always evident.

Your speck may be big or small, I don't know. It may be under the screen. How new is the camera? Then, ask yourself if it really shows up all the time, is it worth sending it in for repair.

For me, the answer was no, not now. If something major happens, I will just add that to the list of things to repair at that time.

Jeff
Thanks Jeff. I suppose there is also the possibility of making things worse by chasing this spot. I hadn't thought about dust under the sensor screen. Has it moved at all since you first saw it?

QuoteOriginally posted by jfdavis58 Quote
I'm inclined to say that you should go running and screaming all over town, post numerous forum threads about the issue; detailing the horror of finding the spot, the horror of trying to remove it, the horror of dealing with service, the horror of a possible replacement and finally the horror of an actual replacement. The idiots you had to explain everything too, the nasty bureaucrats that interfered with your satisfaction---in short pour our all the grubby little details in the most shrill whine you can type. Involve as many people as possible, stir the pot and really let the indignation fly! Finally, you could post an example photo, get the forums most esteemed pixel peepers approval that you do, indeed have a life-threatening situation

or call Pentax Service and see what can actually and meaningfully and rapidly be done to 'fix' the problem.
Thanks.
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04-10-2007, 10:18 PM   #5
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I have this problem too.
That is not a sign of doomsday, but it makes me feel like someone has s--ted in my pants.
04-10-2007, 10:24 PM   #6
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QuoteOriginally posted by skaktuss Quote
I have this problem too.
That is not a sign of doomsday, but it makes me feel like someone has s--ted in my pants.
skated?
seated?
sorted?
snoted?

:-)

My spot has not moved. It seems well behaved and does not bother me. I have much more fun with the other 5,999,999 pixels anyhow.

Jeff
04-10-2007, 11:42 PM   #7
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Original Poster
QuoteOriginally posted by jsundin Quote
skated?
seated?
sorted?
snoted?

:-)

My spot has not moved. It seems well behaved and does not bother me. I have much more fun with the other 5,999,999 pixels anyhow.

Jeff
Must be lodged in there pretty good.

Sometimes a forum can be a good place to adjust one's perspective. That freshly skated feeling has already begun to fade away. Its ultimate effect on my photographic enjoyment remains to be seen. :-)

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04-27-2007, 04:42 PM   #8
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Black spot

I have also noticed a black spot in the upper right of several images, the smaller the apperture the darker and smaller the spot becomes. It`s especially visible in bright sunlight, blue sky type photos.

At first i thought it would be dust due to changing lenses, but on some pictures taken with my mom`s brand new, never had the lens off yet Nikon D80, a similar black spot can be seen, varying in size and darkness.

I also noticed the same description and location of a black spot in some posts where it was considered unremovable dust.

My question is: Could this be the result of to direct light on the sensor? I would really appreciate some input as i was disappointed to see the back spot so pronounced on images taken with the SMC A 50mm 1,7 i bought today...

Regards

04-27-2007, 05:01 PM   #9
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Someone is sure to get their panties in a bunch if I post two sarcastic replies in a single thread; so this ain't sarcasm.

Dust is everywhere.

It gets into machinery and onto various surfaces of the camera. You shake it, blow it swab it off, if you can. Then you learn a long practiced-little appreciated technique: retouching.

If your spot is bigger than a couple of pixels, particularly dark or some how suspected as more than dust, i.e. an actual defect or scratch, you call the manufacturer or a service center and arrange for a technician to look at the problem. Expect to pay a fee.

But chin-up; besides not being sarcastic, this advise is free.
04-27-2007, 08:26 PM   #10
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QuoteOriginally posted by dbh Quote
So I decided to clean the sensor. During this prolonged agonizing endeavour, I came to learn what real dust looks like. Eventually I got things back to dust-free again. But: spot still there.
I suppose you eventually did a wet clean with pads and fluid?
05-01-2007, 08:10 AM   #11
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QuoteOriginally posted by chedoy Quote
I suppose you eventually did a wet clean with pads and fluid?
Thought this thread was dead - yes, I did that, several times. No effect whatever.

So I stopped fiddling over it for a while.
Then, while cleaning a lens last week had the idea to try a small lens pen on the sensor. So I went and bought a new, small lenspen and went to work. Good news: I did not damage the sensor, or introduce any additional spots.
Bad news: absolutely no effect on the dark spot. It must be a flaw in the sensor coating as the last treatment I dished out proved to me without doubt that it is a permanent feature of my camera.

My dark spot is at the lower-left 1/3 of the frame and only noticeable on images that are featureless at that location (fairly rare) and at apertures of f/16 or smaller (not that rare).

My plan now: Because the camera is faultless everywhere else (ie. perfectly functional pop-up flash, accurate autofocus, very accurate and linear metering, etc.), I don't want to risk dealing with the spot at the expense of something more annoying, I don't want to be without my camera, and I know exactly where the spot lives, I will just heal it with a 4-pixel-diameter Lightroom spot-removal tool and move on.

I even made a template image that I can copy the develop setting from and paste onto new photos. Doing that is where I learned that the spot can move around by a few pixels. SR - in action! Quite cool, actually. (If I shake the camera, SR should blur the spot while keeping the image sharp. Need to try that.) But means that automated spot-removal needs to be done either with a larger diameter tool, or just do it manually when needed. SR is nearly always on, it's a feature of the K10D I have come to enjoy.

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05-08-2007, 08:54 PM   #12
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Arrggghhhh! Where did that lump of coal come from?

QuoteOriginally posted by dbh Quote
Decided to check for dust yesterday. Took an out of focus shot at f/22 of the grey overcast sky - and proceeded to pixel-peep. Pretty soon: Ah hah! A dark spot. Gave it the dust-removal shake - still there. Gave it a blow - still there.
Jeez, I wish I had to go through some sort of voodoo sequence to see it. Don't even have a hundred snaps on the shutter and - TaDaaaaa - a spot as big as a freaking lump of coal shows up in the viewfinder while out doing a panorama series of a wetland for the wife. One shot it wasn't there, the next instant there it was, ugly as sin.

Not during a lens change, but one or two pictures afterwards. Come to think of it, the camera may still have been powered up when I did the lens change. I don't suppose that would have helped any, having the sensor energized...

As I was about done I headed for home, hoping it was just the lens. Take the lens off... nope, still there. Well, maybe the mirror/viewfinder. Stop down and take some pics of a white sheet of paper. There it is, all big and ugly - so that eliminates the mirror and viewfinder. Try the sensor shake n' bake cleaning routine about 30 or 40 times. Nope, she's stuck on there (not that I really thought a vibrating sensor would be likely to shake off a piece of dust electrostatically glued to the censor surface when the dust has about nothing for mass).

So a quick search on here finds a few people who have never had a dust problem. It seems the rest of us have to deal with dust, so I guess I have three options.
  1. Do the touchup routine for picture after picture as part of post processing.
    Well, boring, and not something I want to do all the time instead of eliminating the problem. Of course, eventually there's TWO noticeable dust spots, then three, then four, etc. I also suspect they tend to glue themselves to the sensor with the passage of time, if allowed to sit there indefinitely.
  2. Take the camera to a shop for cleaning.
    Not a bad idea, but none around here and I suspect it is kind of spendy to do that just for a dust spot.
  3. Buy the means and learn how to clean my sensor.
    Aside from nightmares about damaging the sensor/camera, this seems the most logical solution.
Option 3 sounds the best. So I try the blower fix first. The actual camera blower brush I have is pretty anemic to begin with. I have no idea what stuff is being carried on that brush right now so I forgo that. Out of the kitchen comes the high tech turkey baster. Check to make sure it's nice and clean. Screw the marinading needle on the end - that gives a very nice directional flow of air indeed. Give 'er a couple of blasts - the lump of coal is still there in the viewfinder. Bummer...

So, I guess I'm now in the market for sensor cleaning tools and methods. My default position would be to use that new tool seen on the web as supposedly Pentax's cleaning solution, but it doesn't seem to be readily available for sale.

There's a tiny little camera shop that looks more like a pawn shop a bit down the way. I'll drop by there tomorrow to see what they have, but I suspect I'm out of luck and I'm back to Internet shopping again for a heavy duty blower and a wet cleaning solution. After browsing around the Web for a couple of hours, Copperhill Images seems like at least as good a choice as anything else, and possibly better. They offer a kit with a Sensorsweep brush and Sensorswipe tools with Eclipse 2 solution for cleaning the Pentax sensors:
Copper Hill Images Wet/Dry Cleaning Kit w/Eclipse 2 for Pentax
Anyone have any feedback on the Copperhill remarketed products and cleaning instructions before I shoot off an order?

This is a BIG chunk of dust... I hope this isn't a case of the camera having to go to a Pentax service center. That would really suck.
05-09-2007, 12:52 PM   #13
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QuoteOriginally posted by Rick Quote
Anyone have any feedback on the Copperhill remarketed products and cleaning instructions before I shoot off an order?
I use something similar to this ‘kit’, though it was purchased individually from Micro-Tools, Camera & Watch Repair Tools - Home. Had a big ol' glob of splooge on my *istD after changing lenses on a windy day. The wet method got rid of the splooge, and I use the dry method between lens changes. Works great.
05-09-2007, 11:30 PM   #14
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This is what I use Rick

here's their link
Kinetronics Corporation - Anti-Static Film Cleaning Brushes And Devices
It's cheap and I find it easy to use. My camera guy showed me how to use it when I bought it from him.

They appear to have several other systems as well, and I'm suddenly thinking that their Clean Air Bag might be nice in dusty environments.
05-10-2007, 01:41 PM   #15
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QuoteOriginally posted by little laker Quote
This is what I use Rick
here's their link
Kinetronics Corporation - Anti-Static Film Cleaning Brushes And Devices
It's cheap and I find it easy to use. My camera guy showed me how to use it when I bought it from him.

They appear to have several other systems as well, and I'm suddenly thinking that their Clean Air Bag might be nice in dusty environments.
Thanks Stu.

It looks similar to the supposed Pentax solution referenced on the web in several places. However, with no camera places about, I phoned Nicolas at Copper Hill and placed an order for their dry bush/wet swab dual solution. Lots of positive comments and no negatives on the Web, so decided to go with that. Then we shall see how it goes.

I see you're an Okanogan boy and a fisherman to boot. If you're ever in the East Kootenays/Northwestern Montana and have an urge to wet a line on the Elk, St. Maries, Wigwam, Flathead, etc, drop me a line.
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