Posted by: David Vernon | November 4, 2008

Cleaning Your Sensor

WagonOkay – if you shoot a digital SLR – well we can’t put this off any longer. You keep noticing that grey smudge in the same spot on each picture. Then two, then three, then ten. You’re starting to lose the war with the cloning tool and the healing brush. Yes – it’s time to clean your sensor.

If you run a point-and-shoot then you’re dealing with a closed system and you can’t clean the sensor short of sending it back to the manufacturer. But you really shouldn’t have to do that. If you never take your lens off your DSLR, well – you can really delay the inevitable but the bad news – a lot of DSLRs just aren’t that well sealed. Stuff gets in.

Now – cleaning the sensor. Except – that’s not what you’re really going to be doing. What it’s time for folks is the cleaning of your low-pass filter – the little piece of glass that sits ON TOP of your sensor and keeps all that infra-red light out of the mix. Let’s face it, your sensor is one heck of a sensitive piece of gear and if you go sticking things in there – well, you’re just going to muck it up. So thank goodness they’ve given us a little filter to clean.

In this day-and-age of increasingly complex digital cameras, you’re starting to see however a whole bunch of in-camera cleaning devices. I mean devices built right into the camera to shake dust off things. And while I envision adding little dust bunnies to a pile in the bottom of my camera every time I turn it off it’s still pretty darn helpful. But eventually you’re going to get some schmutz (another technical term) on the filter that you just can’t shake off. Now – it’s time to go to work.

First of all – before you can do anything – you need to expose the filter/sensor. Someone in the confines of your menus, you should have a choice for “Mirror Lock-Up” for sensor cleaning. You’ll want to take advantage of that. If not, you’ll have to set your shutter speed to “Bulb” and hold the shutter open while doing this. And that’s just messy.

Once the mirror is up, the filter/sensor (okay – let’s just call it the sensor) is exposed. Kinda small isn’t it? Where’s the smudge? I don’t know – down there somewhere. The first over-priced tool to the rescue is the sensor loupe. This isn’t bad as a point of reference – but really when you get right down to it – you’re going to be cleaning the whole sensor so why worry about the details. The loupe is not a bad tool to tell whether or not you got it after the fact but there’s another way to do that. Take a picture of a bright white surface. Sensor smudges show up best against an all-white background. Save yourself some dough and just take before and after pictures.

Sensor cleaning takes on three steps – or levels – to me. The first step is dry-air blowing. If you have anything stubborn this won’t get it done, but at least you can make the other dust bunnies homeless.

The next step is to take an anti-static brush of some kind and brush it over the sensor. The fine folks at Visible Dust make a little device called the Arctic Butterfly. In fact they make plenty of different sensor brushes – and just about every other product you can dream of for cleaning the inside of the camera. The idea behind the butterfly is to spin the brush at a high rate of speed thus messing with the electro-static nature of the brush. This will actually attract dust bunnies and schmaltz (like schmutz but spelled differently) to the brush removing it from the surface. And the darn thing works. PLEASE NOTE YOU ARE SPINNING IT BEFORE YOU USE IT – NOT INSIDE THE CAMERA. DON’T SPIN IT INSIDE THE CAMERA. Oy. Usually just two passes with the brush – in the same direction – one on top of the sensor and one on the bottom – get it done. At this point you can check with a loupe or another white shot to see if you’ve got it. If so – great. If not – well on to step three.

The final step requires you to get aggressive. It’s time to get out the methanol. Often found under the brand name Eclipse (and there are others), methanol is a very clean alcohol-based product that when applied properly will leave no residue on the sensor. And what do we mean by properly? We mean through the use of very expensive and sterile sensor swabs. Two drops of methanol on a properly-sized swab – run again in the same direction covering the sensor will do the job. If the swab is the right size, one pass will do it. The methanol eats through almost all schumtz and leaves you with a minty-fresh sensor.

One bottle of Eclipse could last you for 150-200 years since you’re only using two drops at a time. The swabs, which tend to run about $3 each – are still the method of choice – you don’t want something used or unclean going near your sensor.

By now you should be good to go. If you’re not – well then – it’s time to send it in for a cleaning. I once went through about a half-dozen swabs before giving up and sending a camera into Canon. Never had I encountered such villianous schmutz. You hate to send it in – but by this point you’re out of options. Turning your camera off will return the mirror to its full upright position if you were successful.

So in summary – you’re not going to cook your sensor cleaning it – unless you are really unfortunate (or if you took my advice. Caveat emporer dude). But if you take your lenses on-and-off, sooner or later you’re going to have to do this. Three steps – check after each – only go as far as you have to go. And when you’re switching lenses in a 40-mph wind at a coal mine – you can still take pride in holding the camera opening down to keep the dust out as much as possible.

Now go take pictures. Clean later.

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Responses

  1. Nice write-up! One thing to add…if you really want to see if any little spec is on the sensor (filter), use a small aperture (F/22). I generally just point it to the sky during strong daylight hours. This will point out any little specs as dark spots.

    If you want to take it even further, you could download the picture to the computer and go crazy with levels / contrast to show even the most minor spots (though, that may be overkill). 🙂

  2. My two cents: Be sure to check which type of cleaning solution is appropriate for the coating on the low pass filter. I know my Nikons don’t use plain ol’ Eclipse, but Eclipse E2 because of a tin oxide (I think) coating that doesn’t play nice with the regular mixture.

  3. […] Some time back, we did some articles on cleaning your camera. They can be found here, here, and here. But mighty Moose Peterson has taken it a step further – he’s got four […]


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