Some Ernest Advice From The Workshop
Where do flies go in winter? If you have done pondering that, try this - where does sensor dust come from?
Okay, if you have removed the lens of your DSLR or mirror-less camera in the middle of a paddock at ploughing time or in the discharge path of a council mulcher, you may be forgiven for thinking that is the source of your troubles. Possibly, possibly. If you have not had such misfortune consider the other sources of contamination.
1. Lenses with open clearances and a considerable 'pumping 'action that operates upon zooming or focusing, dirt gets near moving section of lens, dirt gets drawn in, dirt gets distributed.
2. Your clean home is...full of cooking oil vapour as well as other sticky components. Also full of cloth lint and carpet fibres as well as dirt brought in from outside on you clothing. Run yourfinger over the top of a picture frame anywhere in the house. Pass inspection? If you think so, lick that finger. No? Thought so.
3. You get ready to change a lens and take the rear lens cap off the new one. You put it in your pocket, then change the lens, then recap the removed lens. With the cap that is now full of pocket lint. Guess where this goes and where it ends up next time you change. And ALL your rear lens caps are probably just as bad...
4. Way hay, let's go to the drag races. Or Barbagallo. Or the speedway. What is that drifting cloud of blue smoke composed of? Tyres. Guess which part of your camera it ends up on.
5. Spots in the viewfinder of your DSLR.? If they are not seen on Live View - and most times they are not - they are not affecting your sensor view or images.
6. On-board sensor cleaning mechanism not working? See No.2 above - you have glued the gunk to your sensor with just ordinary living. Time for a professional wet-solution clean to get off what a tiny piezo-shake will not shift. Not a home-swab-it-with-something-from-the-internet clean which is closer to the Brillo pad that you might think.
7. When I used to rip bones out of people's head for a living, I was required to do it with clean hands. The hospitals were surprisingly insistent upon this, and went to the extent of demanding that I wash not just to the wrist, but all the way up to the elbow for several minutes with strong soaps. Even though I rarely plunged my arm into the patients up to the elbow. The principle was to get cleanliness in a wide radius around where it was needed.
So also with cameras. No good just cleaning the sensor if the rest of the device looks like an ash-pit. And certainly no point in doing it if the back of the lens is a source of continued contamination. Clients - wise clients - would do well to bring their lenses in for cleaning and pay the extra impost to have the entire camera cleaned - it will extend the period of usability no end if the contamination loading is reduced all around.
And a final thought - but not from Ernest this time. I had been plagued with white spots on my images taken of dancers on a dark stage - particularly when flash illumination was used. Wide angle shots were the worst. I blamed the sensor and the curtains and the dancers and cruel fate...until I looked at the bits of dust that had accumulated on the inside of the UV filter that was screwed onto the 18-200mm lens. No wonder I had white spots - an 18mm lens firing at f:11 can see quite a lot close up to itself and if the dust has bright illumination against dark ground... so I removed the filter for inside shots and the spots disappeared.
Heading Image: Either sensor dust or flak..