Saturday, 13 April 2013

Got Dust Bunnies? Wet Clean Camera Sensor

After a trip out to Cape Liptrap (2.5 hours from my home) where I took a number of images that I thought I would be quite happy with; I discovered in PS that there were spots spread around my images some huge, some small. I did a test shot of the sky and discovered my sensor was filthy.

The photo of the Cape Liptrap Light Station shows the impact of dust on the sensor. The Lightroom "visualise spots" feature shows the worst of the visible dust spots in this image. The spots took a reasonable image that would have been worth putting some time into in PS to perfect and instead made me waste time healing the spots.

I had seen the spots from time to time before - well, at least the bigger ones - they only show up at exposures greater than f/11. The reason they appear after f/11 is to do with the makeup of the sensor housing. The dust is on glass cover over the top of the sensor that is a small distance away from the sensor itself. At f/11 and below the spots cast a shadow so diffuse they can be hard to see. The smaller the aperture the sharper the shadow that is cast until you get to f/22 (or higher) and the spots become very sharp and visible. The light house image below was shot at f/22 for great DOF and to reduce glare from the sky. I took some shots of the sea at f/32 trying to achieve a misty look as the waves broke over rocks and they were awful because of the spots. While you can clean these in LR with the spot remover and in photohop with clone and healing tools it's a pain in the arse.

I started hunting around for someone to clean the sensor and even considered booking it into Canon where I would likely have no camera for two to three weeks. A friend of mine and fellow photographer (much better than me!) David Burren convinced me to have a go myself. Mainly it took knowing that someone I actually knew had wet cleaned their sensor and not damaged it. I had concerns because I'd read both good and bad along with an amazing number of people holding up crossed fingers to ward off the wet sensor cleaning devil. David commented that he has not had to wet clean for ages since starting to use the Visible Dust Arctic Butterfly brush. I decided to buy the brush and a wet cleaning kit suited to my camera body's sensor size.

Before cleaning I took a test shot of the clear sky at f/22 focused to the minimum setting (i.e. the sky is out of focus deliberately).

Filthy Sensor. Spots highlighted by drawing around them.
This photo shows all the dust spots I can find after shooting the sky at f/22 and viewing the raw at 1:1. There are hundreds of the little bastards. I circled them for clarity.

Why has this happened? I'm careful and never leave the body without either a lens or a cap on it. I change lenses quickly with the camera opening facing downwards. The dust will still get in there. I've had this camera for about 2 and a half years and use it in some really filthy environments and sometimes in the wet. The sealing on the camera body and between the camera and lens are good but not perfect - dust will get in - even with the 'L' series glass that I use. The situation can be even worse with the cheaper lenses that I have used in the past because they are not sealed like the 'L's.

I rang around  and eventually found a store which had most of what I wanted. I made the trip into Melbourne from home and bought the Arctic Butterfly and swab kit and the fluid. After getting home I cleaned a work area and cleaned myself then sat down with the camera.

Initially I tried a Giotto rocket blower but that made the problem worse. If you think about it, the blower just sucks in the dust particles from the air and blasts them directly onto the sensor. The Arctic Butterfly did remove some dust but the welded on spots were still there. Next I cracked open the sensor swabs and did a run through - looking at the sensor I could see spots still and streaks from the swab. A test shot came out like this.

This was much better but I still wasn't happy. Many (most) of the spots were gone but there were some stubborn ones, some had moved and there were some streaky areas where the fluid had dried dirty.
Next up was this one where even more of the spots were gone but I still had some streaky areas.

I watched the tutorial video on the Visible Dust website again and hunted out some videos of other people using the products on you tube. I noticed that some of them were putting the fluid drops further up the swab and I decided to try this. This meant that there was less fluid in contact with the sensor and the 2nd pass with the back of the swab would be only just damp.

This yielded a much better result with the majority of the streaking gone and only a few spots left to deal with.

I did another pass with the same technique.

After the final pass there were very few spots and they were very faint. While I could go back and clean again, I've decided not to tempt fate and leave it like this and see how I go on my return trip to Cape Liptrap. There is one new big chunk so I'll give it another pass with the Arctic Butterfly brush and get rid of it that way. I'm quite happy with this process. I got rid of most of the rubbish and have not damaged my sensor or removed the coating or lost my first born child as people on the interweb thingy would have you believe would happen.
After a drying session then a few passes with the Arctic Butterfly (the camera cleaning tool that sounds like a sex toy)  and cleaning the lens in case dust is coming off that - duh. I have now have this wonderfully clean sensor. There is one small smudge but I'm done. I did a couple of test shots and even at f/22 I cannot see the smudge changing anything. Thanks heaps to David Burren for giving me a shove in the right direction and confirming that someone I actually knew had done this deed and lived to tell about it. I guess it is like anything - get the right advice, take your time, be careful and it will turn out well.
I might point out that the cost of brush, swabs and fluid came to about $240 so is about the same price as a professional clean. The good news is I have a clean camera, seven more swabs in the box, heaps of fluid and a brush that I can use until I wear it out.
One note of interest - I definitely would follow the advice and not re-use a swab on the sensor after it has been used once - however, I did make use of them to clean the LCD, the view finder and the body of the camera. No sense wasting them. I even cleaned my computer mouse with one.
The tutorials on make it look easier than it really is. To put it in context - Imagine cleaning a window from 2m away using only a cotton bud stuck on the end of a pole wet with two drops of windex.

What can I say to someone considering the same course of action, or who has come across this article searching for the resolution to their digital acne? I'd say consider if you can do it. You need a steady hand and a great deal of care. The sensor is housed under a sheet of glass but it isn't designed to have any great pressure put on it. Research the products, decide which would suit you, consume every tutorial you can find and have a crack. The worst you can do is bugger your camera completely! If this scares you (it scared me) then drop it off to your favourite service center and let someone else do it. Before you do - take and print a test shot like I did so you can demonstrate how bad it is and test if they made it better or ripped you off when it comes back.

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