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Those Black Spots on your Photos
Posted By: JeffJS, 11-10-2010, 02:01 AM



Many if not all of us have or will discover strange black spots on our photos. Sometimes they show up only when we pixel peep other times we can see them on our little LCD screens on the rear of the camera. There are several causes of these little black spots but mostly, we've discovered the universal truth about our DSLRs. That is, No matter What we do, how careful we are, Dust is EVERYWHERE and WILL eventually end up on our sensors. Rather, the filter covering the sensor.

The sensor and anti-aliasing (and IR block) filter are a sealed unit so the likelihood of dust actually on the sensor is pretty slim. Cameras that flip the filter out of the way for night vision not withstanding. The filter however is a sensitive surface and can be scratched. Once that happens, be prepared to spend $400+ to have your camera fixed (anecdotal evidence only). There are several methods of removing the dust and all have their risks with the possible exception of Pentax's dust removal shake the sensor system.

Now that I've scared you here is the good news. Damaging the sensor filter isn't as likely to happen as one might think. There are hundreds if not thousands of articles out there on the web about the dangers of cleaning your own sensor screen (the filter over the sensor) and how to do it. This is just another one admittedly but I'm writing this hopefully to put the mind of the new guy (or gal) at ease here at PF.

So what to do?

First, Make sure you actually HAVE a dusty sensor (one spec is a dusty sensor). I cannot tell you how many times I've thought I had to clean my sensor only to discover that I need to clean my computer monitor screen instead.

Second, Find the dust. The K20d, the K7, and I believe the Kx all have dust mapping functions. These will show where the dust lies on the sensor. Keep in mind here that the image you see in your photos is actually inverted from what the sensor sees. Objects on the top of your photos are recorded on the bottom of the sensor due to the way our lenses work. If you do not have a camera with a mapping function you can check by setting your lens to the smallest aperture and taking a picture of the sky, a blank wall, a blank white screen on your computer monitor (clean the screen first). Taking the photo is actually better because the dust mapping functions can be fooled by camera motion, texture on the wall, etc. If using a photo, don't worry about camera shake, the dust will show because the dust is not moving (with respect to the sensor) during the test exposure. In Fact, it would probably be better to Move the camera during the exposure to rule out other Objects (like Birds) Being dust.

NOTE that you CANNOT see the dust on the Sensor by looking through the Viewfinder of the camera. Nor will you see dust on the lens. It is also unlikely that you will see dust on the mirror. If you are seeing dust in your viewfinder, it is either on the focusing screen or the viewfinder glass itself. It is annoying but it will have zero affect on your photos

Now that you've Found your dust bunnies (I'll post some sample pictures later on), what to do about cleaning them. Several options are available and if you ask 10 people you'll 10 different answers. In order below are what I do.

1. Clone it out in post processing. This is by far the simplest and least intrusive method. You're going to have to anyway in order to save your photo. This is also the most Tedious method, going through a group of photos cloning out little specs of dust. There are ways of doing it in Batches but from my experience, these require software like Adobe Bridge that can take the (selected) develop settings from one photo and apply it Several. Your software may include the capability to record scripts. Lines of commands that are saved in an action to be recalled later (My watermark and border on my photos are the results of such actions). Either way, if you are only seeing spots on a couple photos once in awhile, it probably isn't worth going beyond option 3 below unless it Really annoys you.

2. Try the dust shaker built into the camera. This is a cleaning mode accessed in the Setup menu of the camera. You may have to do this several times and it may or may not work. Check between shaker activations to see if it's working or if it's just bouncing the dust around the sensor (typical). If the dust is moving, that's good news because it isn't Stuck on the sensor. If it isn't, then a touch the sensor cleaning method may be required.

3. If the shaker didn't work, the next line of defense is the blower. This is as far as Pentax recommends going with sensor cleaning. Once the AA filter is scratched, the entire sensor assembly has to be replaced (remember that $400+ price tag?). The most recommended accessory for this is the Giottos Rocket Blower (get the big one, don't skimp here). To use the blower:
  1. Make sure your batteries are charged.
  2. Turn the camera on with no lens mounted and enter the Cleaning mode located in the setup menu. This will flip the mirror up and open the shutter. While pointing the camera downward, give the sensor a few blasts with the blower. Be careful not to touch the sensor with the nozzle as it may scratch the filter.
  3. Turn off the camera to leave cleaning mode.
  4. Test for effectiveness and repeat if needed.

Side note here. Some will tell you NOT to use Canned air. There are a few here however who swear by using it. If you are going to do so, use a name brand can, expel some air from the can before pointing it at your sensor, and use short blasts only. DO NOT use Compressed air from a compressor. It can be full of water and even may have oil (remember that $400+ price tag?). Do Not use a nearly Empty can of air on your sensor as it may spit propellant at that point (remember that $400 + price tag?)

Ok, The shaker and Blower have failed to get things completely clean. Now you have to actually touch the sensor filter. Several options are out there, these are the ones I've tried and what I have found.

4. Dry clean. This includes things like brushes and sticky wands (Pentax O-ICK1 cleaning kit).

A. Brushes. If you decide to use a brush on your sensor, make sure it is CLEAN and Soft. You can find brushes claiming to be suitable on ebay for about $10. You can also go to the cosmetics department of your favorite store and get a Makeup brush. Whatever you choose to use, again, make sure it is CLEAN and make sure to use it Only on the sensor.

There is also what I call the $90 Spinning Paintbrush. This is a product made by Visible Dust called the Arctic Butterfly. The theory is that spinning the brush real fast will static charge the brush causing it to act basically as a magnet to for the dust. What it probably Actually does, is neutralize the dust so it will just fall off the sensor screen. If this unit works for you, great, use it in good health. I personally didn't see the $90 value in it.

To use either brush method, enter cleaning mode hold the camera facing downward and lightly drag the brush across the sensor. I've seen internet advice saying to briskly whack the bristles of the paint brush across a piece of stainless steel silverware or similar to give it the same type of charge as the arctic butterfly. It may work for you, it never has for me.

B. If the brush scares or fails you there is the sticky wand. I prefer Pentax's O-ICK1 cleaning kit. It is the ONLY thing I've ever tried that worked exactly as advertised. It can be difficult to find and is a little expensive. It is basically a large sticky rubberish object on the end of a plastic stick and it's supplied with a pad of cleaning papers.

The method of use is as follows:
  1. Charge your batteries
  2. Enter Cleaning Mode in the Setup Menu
  3. Carefully and lightly press the sensor with the wand
  4. Wipe the wand off on a NEW part of the cleaning paper. The paper is large enough to handle 4 or 5 of these and you discard the sheet after use. The key here is Dab, Wipe, Dab, Wipe. Don't just dab around the sensor without cleaning the wand between dabs.
  5. Repeat on each area of the sensor until finished.
  6. Check for effect and repeat if needed.

There are also lens pen type devices out there but I've never tried them, use at your own risk. I personally believe (and may be wrong) that these can further Smudge things on the sensor making things worse. If you can actually SEE the dust (magnifying loupes are available for this), and can readily locate it, these lens pen type devices may be an ok way to go.

5. The Dry cleaning methods have failed. The spec is fused to your sensor somehow. Blowing and Brushing doesn't move it and the sticky stick didn't grab it. It may be pollen or some other such microbe that is just sticky and hangs on for dear life. It may also be that it isn't dust at all but a tiny microbial droplet of water has dried on your sensor. If it were just plain dust or some small fuzzy, it probably would be gone at this point. Time for a wet clean.

Again, there are several methods, both commercial and home remedy solutions out there. The Commercial ones are just as expensive as everything else. I've tried this 2 times so I am not an expert on the wet clean but here is what I've run across.

Sensor Swabs and Eclips II. Made and or marketed by Photographic solutions. They offer the guarantee that their products will Not harm your sensor. It is after all, an optical cleaning solution. What it really is, is some type of pure Methanol. The key to using this stuff is that it evaporates fast so there is no need to continually polish the sensor screen afterward (more on that in a moment). In order to fully protect yourself under their guarantee, you also have to buy their sensor swabs. These come typically in boxes of 12 and are available in 3 different sizes. The ones intended for Canon sized APS-C sensors are probably the closest to the Pentax sensor size. These are not Wide enough to Cover the sensor so I don't see what the hubub over size is here.

This is the rub. You put 1 or 2 drops of the E2 on the end of the swab. You then Drag it across the sensor. You Flip the swab so you are dealing with a clean space and then drag it Back over the remaining area of the sensor. Get all that? Now they want you to take a second swab and drag it dry across the sensor in the same manner. Follow that by a third swab. The swabs end up costing about $3+ each as they are $36+ per box of 12.

Now, I will Readily admit that the time I had to go here, the swab and E2 DID loosen the stuck dust particles. It did NOT however, remove it. I had to go to the I-OCK1 to complete the cleaning.

I said I've tried a couple methods of wet clean. Both are really the same but for the second, I made my own swabs out of the third product that Photographic Solutions offers, the Pec-Pads. Like everything else, these have their naysayers. I believe I remember reading that Canon, simply uses a piece of this material and a tweezers to scrub the sensor when They clean them. Good enough for them, good enough for us. Just be careful not to scratch something with the tweezers. You may have to go to the blower afterwords to get rid of a fiber or two.

Other wet methods commercially available are from Visible Dust (the spinning paintbrush people). The method of using their products are probably a hybrid of the sensor swab technique and what I describe I read (that is READ) Canon does. I have not invested any money in their cleaning system so I cannot report on how well it works (or doesn't).

6. The last and final method of cleaning the sensor is to have someone else do it. This can be a local shop or factory service. If you're really brave, hire the next guy you see walking down the street to do it. The one time I looked into having it done locally, the price was $50 and there were no guarantees against it reoccurring (they would be silly to offer that sort of guarantee). I read here on PF of someone paying Pentax service $170 for the service. I don't know what else he got for his money though.

The bottom line is this when it comes to cleaning your sensor. As long as you are careful with your methods and materials, it isn't as daunting a task as you may fear. There are those who swear by their methods as if they are the second coming. There are others who will swear against the same methods just as passionately. Start lite, Find what works for you, and stick with it. Unless you've been out in a pollen storm or it rained on your sensor or you spit on it trying to use your built in blower, a WET clean is rarely needed.

_______________________________________________

To AVOID dust. A few tips that I think work for me.
  • Keep the Mirror box and lens mount clean.
  • Change lenses in as clean an environment as possible. When changing lenses, Point the camera downward to keep anything from falling in to the mirror box. Avoid Wind hitting the camera while the lens is off. Also, turn off the camera when changing lenses.
  • Keep the rear of your lens clean.
  • Keep your rear Lens cap clean.
  • If you use a Body Cap, keep IT clean too.


(Stay tuned)..




Last edited by JeffJS; 02-26-2011 at 10:48 AM.
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11-10-2010, 06:50 PM   #2
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Photos of different types of dust, smudges, etc

The Check Mark (photo of the dog peeking around the corner). This is/was most likely a fuzzy of some sort. This type is usually easily removed with the blower if the shaker doesn't work (which in this case, it didn't).





11-10-2010, 07:01 PM   #3
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Clone It Out

One of the other ways I mention to deal with dust is to clone it or heal it out (they both work equally well). The first photo I show below is basically a 100% crop from a photo out of my IR modified K20d. You can easily see at least 10 or so dust problems (I've never cleaned this sensor).



The Next photo shows all of the cloning and or healing I've done in ACR on Photoshop CS4 (other versions offer this feature as well).




That's all well and good but as you can see, VERY tedious to do with several photos. This is where Photoshop earns it's money or at least for the Adobe Bridge. The third photo, I've copied the Develop Settings from that photo. This copies Everything that you've done with ACR, including the spot healing and cloning (as well as white balance, crops, alignment, etc). Here is the beauty of this. Remember I said that it doesn't matter what type of photo you take, the dust and spots will always be in the same place. In the fourth photo, I'm showing you that any of the develop settings can be copied to multiple files.






The next photo simply shows the result of the dust cloning.




Now, what if you don't have CS4 Bridge? You can also record an action (in software that allows it) as you go through and clone out your dust in a JPG edit. Remember again, the dust isn't moving with respect to the sensor. So, as long as you run your action or script before you do any resizing or rotating, the script will always act on the same locations within the photo. What if you don't record RAW but have Bridge? Simple, you can open JPG files In ACR and do just about everything you can with a RAW file.

11-10-2010, 07:03 PM - 3 Likes   #4
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Cloning Results

The overall result of the above operation...

The second photo shows the result of the paste develop settings. Taken seconds after the other photo (and I see I still missed a spot or two ).







06-07-2011, 07:20 AM   #5
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Thanks for such an informative post.
11-22-2014, 07:29 PM   #6
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and still finding it informative and useful. Thank you
12-07-2014, 01:10 PM   #7
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QuoteOriginally posted by First Poster Quote
Carefully and lightly press the sensor with the wand Wipe the wand off on a NEW part of the cleaning paper. The paper is large enough to handle 4 or 5 of these and you discard the sheet after use. The key here is Dab, Wipe, Dab, Wipe. Don't just dab around the sensor without cleaning the wand between dabs.

2 points here:
  1. I want to emphasise the "dab" action. The O-ICK1 cleaning tip, being slightly sticky, goes straight down on a spot on the sensor, pressed down slightly (this light pressure will not damage anything), and then lifted straight up again, bringing with it dirt particles and oil droplets. There is no lateral movement involved, so there is no risk of scratching the top of the sensor stack.
  2. Then you move the tip to the sticky paper pad. Here, you pick an unused part of the pad page and press down. This will pick the grim off the tip of the cleaning rod. Then you go back to the sensor for another dab. I don't wipe at all on the sticky paper. What you need to do is keep a mental image of which part of the page you've used (in a row-and-column fashion), so that the next press down (really a dab since again no lateral movement is involved) will not be to a soiled section of the pad, possibly leading to grime getting back to the tip of the rod. This way, the use of the pad page area is minimised. You could even write a little note e.g. "only top half of page used" so you'd know where to start next time you use it. When the page is fully soiled, you pull off the page off and expose a new page in the pad. I've used my pad now for the K100DS, K20D, K-5 & K3 and I've still got pages left.

Watch this YouTube video to see the action you should use:

Note: recent Pentax DSLRs have a Dust Alert mode in their menu. You point the camera at a uniform wall or a clear part of the sky. The mode automatically stops down the camera (dust spots are most visible at very small apertures), takes a shot and then shows it on the back LCD screen. The map only has a complete white surface with dark spots clearly visible. The image is displayed the location of the red orientation dot on the mount ring so you can work out the orientation of the dust map. This image is also saved on your SD card in a DUST folder and called DUST.JPG, but there is no mount ring included for orientation.

I find that a good way to get spots on your sensor is to change your sensor at the beach or in a boat, with any wind around. There must be minuscule droplets of sea spray in the air.

Also be careful changing lenses if there is any drizzle at all, as any raindrop contains sufficient pollution to leave a spot when it dries. If you must change a lens under these conditions, make sure the camera is always pointing downwards during the change.

Can anyone tell me what these circles are? - PentaxForums.com

K100D Sensor Dirt....... - PentaxForums.com

Dan.

Last edited by dosdan; 12-07-2014 at 01:56 PM.
12-08-2014, 02:58 AM   #8
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Thanks for the info, some useful tips here.

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