I received a slightly over-direct e-mail from Nicholas at Copper Hill Images concerning a recent post I made about sensor cleaning.

I won’t post a private e-mail here without permission. The gist of it I’ll get into below but this is as good a place as any to leave some room to talk about sensor cleaning.

[How to clean sensors after the jump.]

Why is this a problem when it wasn’t before

Well with film, any dust that managed to get in there would get swept away as you advanced the film. Also sensors are charged so they tend to attract dust statically.

What does it look like?

In outdoor photos it looks like a black or grey dot in sky. This is because the sky is really bright, flat, and usually your camera is stopped down a lot and the spot created by the dust will cast a nice sharp shadow.

It’s really annoying ignoring this because you can get sick of using the heal tool in Aperture or Photoshop. Nikon Capture and the new Canon Rebel XTi can use dust reference photos but that’s really a hack.

How about dust in my viewfinder?

Spots you see in your viewfinder don’t affect the final image. This is because that dust is on the outer surface of the mirror (which gets flipped up during exposure) or on the bottom of the pentaprism (the top inside of your camera box).

They’re really annoying though so if you want to get rid of them, just clean both those areas like you would a sensor.

Must I clean?

If there is dust in your photos, you must clean it. But it is worth it to go over some ways to avoid it:

If you never change out your lens, you probably won’t have any dust on your sensor.

Olympus has a technology that ultrasonically vibrates an element on top of the sensor where the dust will settle on on camera startup. (Nowadays, this can be bypassed for a quick start by pressing the shutter button down halfway). Nine times out of ten, this shakes the dust off the sensor and you don’t have to clean. The cool thing is that a number of companies now license this: Panasonic, Pentax, and now Canon being the most notable.

Dust-shake is a great idea for consumers who rarely change out lenses, but us outdoor types have to resort to cleaning sooner or later.

The simplest solution: a bulb blower

The simplest solution is to get a bulb blower to squirt a puff of air on the sensor. I recommend the Giotto’s Q-ball from 2filter because it’s marginally more compact than the others and might fit in your camera bag. If you need convincing, Bob has a more complete article.

Whatever you do don’t buy a can of compressed air. If it gets too close to the sensor, some of the propellant they use might splatter on top of the sensor and I’m told that it’s a pain to get off.

You can get at the sensor by reading how to set the mirror-lock-up function in the camera (which is different from Mirror-Up shooting if you have a high end camera that can do that). In many cases, the camera manufacturer recommends you buy a external power cable, but I just make sure that my battery is fully charged. I’m not leaving the mirror up for very long, anyway.

Then all you do is squirt a few puffs of air onto the surface of the sensor. It’s sort of like a poor-man’s dust shake with all the consequences that entails.

Escalation: The sensor brush

This solution was popularized by VisibleDust. The idea here is that you blow air onto a bunch of bristles to statically charge them and blow off any dust, then you sweep it across the sensor in mirror lock up: one swipe only. You repeat as desired (I found two times is enough, but you won’t get everything). Personally, I also hold and leave the camera face down when I do this process.

You can used compressed air for this if you like since the propellant doesn’t touch the sensor. In the field, I use a small brush and the Q-ball.

Since my Sensor Brush is so egregiously expensive, I recommend the Sensor Sweep instead. Here is a comparison of the two solutions—it’s a little bit dated since you use the same method of charging the brush for both nowadays.

Maybe you may feel that $90 isn’t asking too much given the cost of your high end camera body, or maybe you want to support the people who came up with the idea, or believe the marketing on VisibleDust’s website. You are entitled to that and purchasing the latest “Artic Butterfly” or whatever from Visible Dust. I’m just stating my opinions.

I will say that I own two Sensor Brushes which I paid retail price for back in the day and I’m very happy with both of them. If I had to do it today, I’d buy the Copper Hill SensorSweeps.

This is the solution I use, but it won’t always get every tiny spec of dust.

The definitive method: alchohol and pecpad

I first read about when Thom Hogan was describing Nikon’s in-house approach. The idea is basically to put methanol on a lint-free pad and use a mini-squegee to swipe the sensor. I haven’t done this, but I think it’s obvious why this will work wonders.

It’s worth mentioning at this point that you are not actually sweeping/swiping the CCD/CMOS sensor itself but a highly scratch resistant covering which sits in front of the microlenses, hotmirror, and bayer filter of the sensor. So there is no need to panic about this process.

By the way, the Thom Hogan article also has a great tutorial in the sidebar on how to evaluate how dirty/clean your sensor is.

The best instructions on doing this method (along with a reasonably priced kit) are at Copper Hill Images. Because of the popularity of this tutorial, many people call this “The Copperhill Method” which annoys me to no end and is the cause of my run-in with Nicholas.

(In his defense, in the thread that probably touched things off I erroneously accuse Nicholas of claiming credit for inventing the pecpad solution. I didn’t realize that Copper Hill doesn’t actually claim that this method is the “Copper Hill Method,” it is others who are doing so.)

My response

Apparently, someone has been smearing Copper Hill so my post touched a nerve. Oh well, I’ve been saying the same thing (above) for years now—I may be wrong, but at least I’m consistent! I still think there is a big gray area between not denying and not correcting.

Nicholas,

I cannot comment on your competitors. I am sorry if you and your company is being smeared since I have a number of friends who use your products and I recommend your Sensor Sweep to anyone who wants to purchase the VisibleDust Sensor Brush I own.

I read your tutorial way back in the day, but I never noticed it being all that different from existing pecpad solutions except in level of detail and the addition of included photos, as well as the ability to purchase the necessary components at a reasonable price.

If you have read my posts on Flickr concerning this I have been remarkably consistent and they have been based on personal experiences.

1. I own the VisibleDust Sensor Brush but recommend against it because I feel it is overpriced by today’s standards. At the time, it was the only brush solution on the market.
2. I recommend your Sensor Sweep instead since it is reasonably priced.
3. I dislike when people refer to the pecpad solution as “the Coperhill Method” since solutions such as Thom Hogan’s documentaiton on Nikon’s in-house method predate it.
4. I myself haven’t needed to resort to a pecpad solution, if I would I’d probably consider buying your SensorSwipe kit.
5. On a personal note, I don’t find a problem with people who use bulb blowers. For them it seems to work fine, though it’s not as good as a brush solution which in turn isn’t as good as the pecpad solution. I figure it can’t be denied that the more powerful solutions are also more inconvenient.

I hope that explains my position adequately. I’m sorry I touched a nerve. Believe me, it was unintentional. I think highly of your products and the service you give in providing tutorials to the internet photographers out there.