Camera Sensor Dust Reference Page

My Sensor Dust Reference Page

In a recent post about silly extreme macro photography, I commented that some of the small-aperture f/22 shots weren't good for much except illustrating that I need to clean my image sensor. Just as a small light source like a flashlight casts a sharper shadow than, say, a large light source like a picture window, a small aperture lens setting highlights any dust on the camera's sensor by allowing it to cast a sharper shadow on the sensor's photosites, yielding noticeable spots in the resulting picture. Some of my silly macro shots had blotchy dust spots on them.

I clean my D200 sensor about twice a year. There are many methods one might use to clean a sensor, and for some reason debates about them can become quite lively. I happen to use this popular method, but whatever method you choose, you need a concrete way to determine just how dirty or clean your sensor is. This is useful both to know when it's time to clean it, and to ascertain the results of a cleaning you just performed.

The best way to test your sensor is to take an out-of-focus picture of a smooth field of brightness, with a very small aperture (high “f” number) lens. Common methods are to take a picture of a clear sky, or of a brightly-lit white wall. I generally have neither handy, so make my computer screen white, and use that.

As a joke for something I no longer remember, I once made a dust reference page that was totally white, except it had a few instructions on how to take a test shot. Well, it turns out that I return to that joke page twice a year when I clean my sensor, as sort of a checklist of things to do to ensure a reasonable test:

Set camera to lowest ISO and aperture-priority to highest-numbered f-stop (e.g. f/16, f/22, ...). Set lens to its highest zoom and manual focus to infinity. From close enough so that only white fills the viewfinder, aim at white of screen and take a metered exposure.

The first time I cleaned my sensor, it was a hair-raising event full of stress and uncertainty that entailed perhaps a dozen cleanings over the course of half an hour before I felt it was much better than when I started. A little experience goes a long way, and when I cleaned my sensor today, it took about 10 seconds. I took a reference shot (using my test reference page, of course 🙂 ) and was satisfied to find more or less a perfectly clean sensor.

As silly as a white page with a few common-sense instructions is, it's actually useful, so I thought I'd post about it.

All 3 comments so far, oldest first...

Note – that blank white screen is also quite good as an I Need To Clean Clean My Computer Monitor Screen Notification page.

— comment by Marcina on January 3rd, 2008 at 9:28am JST (16 years, 7 months ago) comment permalink

Hi Jeffrey: Regarding cleaning sensors: I’m not recommending this, but out of despiration on a trip out of the country I tried something for cleaning the sensor that seemed to work very well. Green packaged magic Scotch tape is mentioned as a way to lift dust off a sensor without leaving residue, on a blog site or two. I know it sounded too simple, but I was without anything else and my attemps using other methods left more junk on the sensor than I started with. I took a short length of it and using a brush simply layed it on the sensor, much like brushing on wall paper and then lifted it off. I have done it a couple of time since. Again, I am not recommending it, because I can’t say for sure that some damage might not result, but it seems to work for me.

Personally, I’d rather just use part of my T-shirt before I’d use tape, but that’s just me. In a pinch I’ve used compressed air before (which itself can be fraught with danger), but I can’t possibly imagine using tape. —Jeffery

— comment by Bob on February 21st, 2009 at 10:56am JST (15 years, 5 months ago) comment permalink

Awesome work – I really appreciate your plugins and miss them after losing them with last upgrade.
Hint here: the link to your cleaning method does not work anymore. would be interested in what you use 🙂

Mostly I just use (carefully) an air blower, but if something’s stuck, I use some kind of solvent with some kind of special cloth… I don’t remember offhand the name of either, sorry. —Jeffrey

— comment by Thomas on January 7th, 2018 at 2:24am JST (6 years, 6 months ago) comment permalink
Leave a comment...

All comments are invisible to others until Jeffrey approves them.

Please mention what part of the world you're writing from, if you don't mind. It's always interesting to see where people are visiting from.

IMPORTANT:I'm mostly retired, so I don't check comments often anymore, sorry.

You can use basic HTML; be sure to close tags properly.

Subscribe without commenting