Dust, the natural enemy of DLSRs

Trying to photography in the Saudi Arabian Desert has highlighted the issues of dust and (mirrored) DSLR cameras. Basically each time the mirror folds up to take a picture and exposes the sensor. The desert wind pick up fine sand particles and dust and it penetrates everything from your ears, anything you touch and eat, even to filling your back pocket. When you change lens for example some dust can find its way inside your camera and onto the sensors. Leaving those annoying little spots on your image. The image above has the very clear black spot of a fine sand particle but also so many ghosted dots (also dust) that I gave up pointing to them all, in the photo above.

So what can you do about it?

The first thing to remember there are now good tools to recover any photos you have taken that have unfortunate spots. These are generally versions of cloning tools that allow you copy the texture/detail for a nearby area over the spot and thus erase it. In lighroom this is called the spot removal tools and cab be found in the development module. In Picasa it is called Retouched and found in the basic edit tools. In AfterShot Pro it is called heal (which just fixes circular blemishes like dust) and is found in their layer manager.
The better solution is to clean your sensor of dust as soon as you detect it. This is relatively easy for most camera but a few makers and models do recommend that you get the camera cleaned by the company or their designated agents (and that can be expensive!) For the rest of use check you camera manual and carefully follow the instructions. Some cameras like my Pentax K20D has a sensor shake mechanism to dislodge dusk particles, and often can do this at start-up. However bi also just find the setting to clean the sensor which lift the mirror and expose the lens. With the lens remove i them a conventional blower with the brush removes and with the camera upside down I give the sensor a good blast of air. Remember you must never touch the sensor with anything, hold the blower a couple centimetres away (approx. 1”) below the sensor and squeeze the bubble several times pointing at different parts of the sensor. I find this approach works well, if the dust is fresh. If the dust have been there a while it may take a couple of cleanings to get rid of all the spots. I have previously posted that a good way to find dust spots is to photograph a clear sky.

I have found giving my camera a strange turban-like bit of head gear, made from a face washer rather than the traditional tea towel patterned cloth in the saudi style, and a rubber band has helped a lot. Although it will never be white again. Those familiar with hitch hiker’s guide to the galaxy will know that a small towel is an essential travel necessity, (especially so for a photographers). And importantly I don’t change lenses out in the open.

Spring Cleaning

Its the first day with a really clear sky I seen in a while and a perfect time to check on the cleanliness of the sensor on my sensor. I wrote some time ago about DSLR’s dirty little secret and how to use a photo of the clear sky to detect the presence od dust on the sensor. My current Pentax D20 is a well engineered unit and includes a dust reduction, a dust detection and a dust cleaning system (it shakes the sensor, with the mirror lifted). However small dust particles always seem to be get into most cameras. So I regularly check using my blue method. Now I additionally slide the highlight and shadow bars across while zoomed in to help detect dust. Ok often its barely visible (And not seen by the Built-in dust check) but I now know it there. Generally just one or two runs of the dust removal procedure followed by another blue sky photo is enough to convince me my camera is clean.
On my Pentax dust removal involves taking the lens off holding the camera facing down and selecting the dust removal from the setup menu, the whole camera appears to shake for a couple of seconds, that's all it takes. Older SLRs, which don’t shake themselves, can be cleaned by selecting the mirror up and using clean air blasts (you can buy specialty air-pressure pack from a camera store or use an old fashion bulb blaster, just take off the brush) across the sensor area. It is important not to touch the sensor or mirror directly with anything.
WARNING some camera manufacturer/models, notably many Nikons, claim such air blast cleaning voids the warranty and you need to get a certified dealer to clean the sensor (check your camera manual)