Sunday, July 31, 2005

The danger of cleaning your digital SLR sensor

One of the problems with a digital SLR camera which uses interchangeable lenses, such as my Canon 300D, is that dust can build up on the sensor. The first time this happened, the camera was still under warranty, so I sent it back to Canon Canada for cleaning. They did a reasonable job, but it took 6 weeks for them to send it back.

Since then there have been a number of cleaning kits released onto the market, one of the ones that has received the most praise from professional photographers is the Sensor cleaning system from Visible Dust of Edmonton. After reading a number of reviews (e.g. #1, #2, #3) about the Sensor Brush, Sensor Clean and Chamber Clean products, I decided to purchase all three products from a local retailer here in Vancouver.

After reviewing the instructions and sample videos on the Visible Dust website, I set up a workspace on the dining room table and set to work.

Before attempting to clean the sensor I took an image of the sensor before cleaning, which is shown below. To do this you take an image at the highest f-number you can of a uniform subject that's out of focus. I used a sheet of white paper and took the images with a Canon 100 mm macro lens at f32. The dust appears as the dark spots all over the image.

Original state of the sensor

After cleaning using the Sensor Brush 3 times, the treatment has removed a lot of the dust, but some appeared to be persistent. Remember that the dust is the small dark spots, not the hazy background, which is the result of the extreme adjustment of the levels in the image.

After cleaning with the Sensor Brush (x3)

So I decided to use the Sensor Clean option, which consists of a sterile polyester tipped swab and a proprietary cleaning solution supplied by Visible Dust. I followed the instructions to the letter, 2 drops of the liquid onto the swab then wipe the sensor and then using three more dry swabs clean off the entire area.

As you can see from the next image, it did remove a number of the persistent dust spots from the sensor. But notice the small dark line appearing on the left hand side of the image.

After cleaning with Sensor Clean

After seeing this dark spot appear, I once again examined the sensor and noticed that the line appeared to be between the sensor and the filter that sits on top of it. Because you are not actually cleaning the CCD sensor directly, there is an infra-red filter that is mounted on top of the CCD - this is where the dust accumulates.

Another shot of the sensor 30 minutes after the previous image

Taking another shot 30 minutes later, it was becoming obvious what had happened. A small amount of the sensor clean solution had run down between the CCD sensor and the infra-red filter which sits on top of it. Presumably, the filter wasn't completely sealed fully around its edges, allowing the liquid to penetrate under the filter. This last image shows the full extent of the damage.

Further images show the dark area has stopped growing and presumably the liquid has dried up. Not without leaving a large and disfiguring stain on the sensor.

Now this isn't going to be easy to resolve. In order to clean this stain away would require removing the infra-red filter from on top of the CCD and cleaning the CCD directly. This isn't something that I feel comfortable or qualified to do, the camera will be sent off to Canon to see if they can salvage it.

So my conclusion from this experience is that you need to be very careful about using any liquid cleaners on the CCD sensor of a digital SLR camera. Obviously there is a real danger of liquid creeping under the IR filter and causing what appears at the moment to be permanent damage.

I have also sent off a note to Visible Dust and will post any feedback I get from them.


Below is a copy of the correspondence with Dr Degan of Visible Dust over this issue. I have removed e-mail addresses of individuals, but everything else is verbatim from the conversation. I will update as new responses are received.
Date: Sun, 31 Jul 05 23:27:49 +0000
From: Darryl Luscombe
Subject: A problem using the Sensor Cleaning solution
I wanted to let you know that I have experienced a major problem with
using the sensor cleaning solution. It appears that a small amount of
the solution wicked down under the IR filter and spread between it and
the CCD sensor. I didn't read anywhere that this could be a problem with
using the Sensor Clean system, and would suggest that you may want to
advise people of the danger of using liquids to clean their sensors -
even when following you directions to the letter.
Full details are on posted my blog here:
Darryl Luscombe
Vancouver, BC
Date: Sun, 31 Jul 05 17:59:46 -0600
From: Visible Dust
To: Darryl Luscombe
Subject: Re: A problem using the Sensor Cleaning solution
Hello Darryl
First of all, one has to make sure the conclusion that person is drawing
from his experience is the right one. I suggest to clean that smear using
another solution of ours which either could be smear away or chamber clean
and applied on the sensor. They are more powerfull in removing the smear
caused by any method from the sensor.
One has to be really very careful in reaching conclusion with any one single
person experience and generalizing it. First of all, assume that conclusion
is correct and there is a gap, this is considered to be a DEFECT and the camera
should be taken back to canon for repair. *There should not be any gap in sealing*
as using even the bulb blower will force some dust underneath the cover glass.
So you are reaching a conclusion based on a defective sensor .
Just think for a second, if you have double layer window for insulation,
what happens if there is any gap, mositure will accumulate and the glass
indow becomes opaque and usless to see through. The same thing happens if
there is any gap between the sealing, the mositure and condensation will
appera under the cover glass if you start using your camera in winter time
eventually becomes useless, IS IT THE FAULT with sensor clean. of course
NOT. as a metter of fact one the advantages of sensor clean is that contrary
to methanol based cleaning solution that are GLUE REMOVER and can remove the
sealing , sensor clean is not. therefore this is considered to be one of the
advantages that is posted in our website.
So my conclusion is that first try to remove the smear first using other
solutions such as smear away as the sensor clean can not remove the smear,
once it was decided that this is due to the hole in sealing, this is
considered to be a defective sensor and camera should be taken to
manufacturer period. Even without cleanign you will have problem with this
kind of defect in future.
thanks technical Dr. Degan
Thank you for choosing Visible Dust to clean your sensor!
Visible Dust

Date: Mon, 01 Aug 2005 00:20:06 +0000
From: Darryl Luscombe
Subject: Re: A problem using the Sensor Cleaning solution
Dear Dr Degan,

Thanks for the prompt response.
However, I do not believe I am jumping to conclusions in my assessment
of what happened. The smear is not on top of the IR filter, and
continued to grow over a period of 30 minutes. This was obvious from
viewing the surface of the sensor in reflected light and the images I captured.
Also, I don't understand your contention that this is a smear on the
surface of the filter. The only liquid to touch the surface was Sensor
Clean and it supposedly is residue free and is not a "glue remover". So
I don't understand, by your own reasoning where this smear would have
come from, especially as it grew in a very liquid like fashion over the
course of 30 minutes. If it was a smear on the surface, the sensor clean
would have removed it, as it was still growing. (not static)
I agree that this may be due to a pinhole in the seal around the sensor,
but as you didn't warn that this could be a potential problem, I think
it is a real issue that should be acknowledged.
After all, Canon only recommends the use of a blower for cleaning the
sensor (or returning it to Canon). Perhaps their rationale for not
recommending third party solutions such as yours is that there is a
danger of liquid wicking down under the filter from small pinholes in
the seal. Which to my mind can't necessarily be considered a "defect" if
a liquid seal was never a design consideration in the first place, but a
dust seal may have been.
I have to say that I am disappointed by your response to this issue. I
also wish to point out that I haven't only mentioned Sensor Clean on my
blog, but rather that, " conclusion from this experience is that
you need to be very careful about using any liquid cleaners on the CCD
sensor of a digital SLR camera. Obviously there is a real danger of
liquid creeping under the IR filter and causing what appears at the
moment to be permanent damage."

From: Visible Dust
To: Darryl Luscombe
Subject: Re: A problem using the Sensor Cleaning solution
Hello Darryl
There should not be any hole in the sealing. The sealing should be tight and
liquid proof. This is manufacturer's problem and should be repaired by them.
canon refers a lot of customer to us, as a matter of fact canon headquarter
in Netherland( Europe) is one of the centers that we get a lot of referral from.
My suggestion is take your camera to canon, DO NOT DRAW YOUR CONCLUSION, ask
them simply to clean it, what answer they can come up with, the sealing is
broken, this is not your fault, you discovered it. after all this is not
scratch. Broken sealing is considered to be a camera defect and should be
repaired by canon.
Even if you do not use any liquid, dust will eventually find its way under
the glass . If liquid can get under the glass so the moisture and so the
condensation and so the change in air pressure during the flight.

There should be no way liquid to get under the glass even if you immerse the
sensor in liquid , If it does therefore, the sensor is defective. The change
in air pressure will take dust under the glass too as you travel with the
camera in airplane. So the sensor should be sealed and tight.
thanks technical Dr. Degan

Date: Mon, 01 Aug 2005 01:06:26 +0000
From: Darryl Luscombe
Subject: Re: A problem using the Sensor Cleaning solution
G'day Dr Degan,
Sending my camera to Canon is something that I intend to do, but as it
is out of Warranty, any repairs won't be covered by Canon. In fact, such
repairs can be a major issue, as the cost of repairing or replacing a
CCD sensor, is not simple and may not be economic compared to the cost
of a replacement camera.
Despite your rationale for what has occurred, I would strongly suggest
that this issue is something that you should acknowledge on your website
and promotional literature. Even if your contention is that this is due
to a manufacturing defect (which I don't necessarily agree to), then
many of your customers may experience a similar problem using sensor clean.
I do not consider it acceptable behaviour for a company to simply
dismiss this potential problem of the use of their products as "someone
else's fault". I don't understand how you can be so certain that the
sealing should be "liquid proof". I have never seen anything from Canon
that would indicate that this is the case, or something that they
It appears that you are the person making assumptions here. I would
strongly suggest that you may need to warn people about the potential
consequences of using liquid cleaners on their DSLR cameras and the
possible damage that can ensue.

[No response so far...]
Update 21 October 2005

A Spectacular outburst on Mount St Helens

There were two stronger tremors last night at Mount St Helens, one of which caused a spectacular outburst from the crater.

The first, at 23:09 was a M3.0 tremor that also caused a small outburst from the lavadome. The second occurred at 02:24 and was slightly stronger at M3.3 - but this tremor was associated with a spectacular outburst from the lavadome.

The USGS are this morning reporting that, Another large section of the spine at the north end of the growing lava dome collapsed overnight in a rockfall. An M=3.3 earthquake at about 2:34 a.m. this morning was the likely trigger.

Saturday, July 30, 2005

Ever listened to a planet?

No this isn't some new age conciousness expanding trippy thing, and I doubt you'll be able to dance to it, but scientists have released a recording of the sounds of the planet Saturn! These sounds were recorded by the Casini spacecraft last November and just released by the Radio and Plasma Wave Science team.

It's worth checking out as it definetely has an other worldly sense to it. Listen to a wav file of the sounds or listen and watch (requires java).

Mount St Helens rocks and rolls

Over the last 24 hours there have been three tremors greater than magnitude three (M3.0, M3.0, M3.2) and another of M2.9 that also resulted in a bright outburst from the lavadome.

This morning finds clear weather on Mount St Helens. There is also quite of bit of dust being kicked up by small landslides all around the crater walls - something that seems to have become quite common over the last few days, especially in the morning.

Thursday, July 28, 2005

The sun just burped - BIG Time!

It looks like a big solar flare just erupted from the sunspot emerging over the sun's limb. This large mass of solar material is huge - the earth would only be a small dot on this image. It's probably the same sunspot that has been causing a string of large solar flares over the last week.

Looks like it is still capable of generating some big solar flares - which will hopefully mean some good aurora displays in the coming week or so...

Image Credit: NASA/SOHO

Mount St Helens puts on another good night time show

There were two bright outbursts last night from the lavadome on Mount St Helens. The first at 22:35 corresponded with a M2.5 tremor and the second occurred at 00:45 - but the automated earthquake detection system hasn't listed a quake for this outburst so far. Althought there is clearly a quake on the webicorder trace around this time. New movies of last nights show have been posted!

Tuesday, July 26, 2005

Cassini glimpses an alien world

On 14th July, the Cassini spaceprobe approached to within 145 kilometers of Saturn's moon Enceladus. Today NASA released images and a preliminary analysis of the fly-by.

The image at closest approach to the moon shows a bizarre and alien landscape of boulders, valleys and faults. I tweaked the NASA image a little to partially compensate for the motion blur to hopefully make the features a little more easy to view (see below).

For a moon that's basically a big iceball, this looks pretty interesting!

Image credit: NASA/JPL/Space Science Institute

is somethign happening on Mount St Helens?

What's going on down at the front of the crater on Mount St Helens? The images from the Volcanocam over the last couple of hours (e.g. Volcanocam archive, Brian McNoldy's time lapse sequence) have been showing steam or dust rising up from the front of the crater... a rockfall causing dust to blow in the wind? steam? ??? Anyone have any info on this?

Sunday, July 24, 2005

Mount St Helens continues to rumble

There was another M3.3 earthquake last night, and other lesser quakes around 21:50 (M1.0) and 02:00 (M2.5) which caused visible brightenning of the glow from the lavadome. The increased seismic activity is gathering some interest in the media (e.g. this AP article in the Olympian) and many others.

Saturday, July 23, 2005

Lavadome growing, crumbling and showing off at night.

Since the 15th of July there have been 7 earthquakes greater than magnitude three recorded at Mount St Helens. The latest was a magnitude 3.2 quake at 02:38 this morning, which was also resulted in a bright outburst from the lavadome in the crater. The heightened level of activity is associated with the crumbling of the lavadome structure, as evidenced in this photo from the USGS.

The USGS/CVO also report that the, volume of the new lava dome was about 54 million cubic meters (70 million cubic yards), or about 60% of the volume of the lava dome that grew in the crater from 1980 to 1986. The rate of addition of lava to the dome from mid-May to mid-June remained at about 1.5 cubic meters (2 cubic yards) per second. The high point of the lava dome (the actively growing spine) on June 15 was 2335 meters (7660 feet), but it is currently lower than that owing to the recent large rockfalls from the spine.

Thursday, July 21, 2005

Another day, another tremor, another good show on Mount St Helens

Early this morning (03:00) there was another magnitude 3.1 earthquake and associated bright outburst from the lavadome on Mount St Helens. This is almost getting to be a regular occurance!

Wednesday, July 20, 2005

Another tremor, another bright outburst...

There was another strong (3.3 mag) tremor last night at 22:19, which corresponded with another bright outburst of activity from the lavadome on Mount St Helens at the same time as the bright moon was passing overhead - check out an animation of the display here.

Tuesday, July 19, 2005

The glow on Mount St Helens revealed!

In a series of photographs taken on 14 July 2005, USGS photographer Elliot Endo has captured the beauty and details of the source of the nightly glow from the lavadome in the crater of Mount St Helens... Great shot!

Credit: USGS Photograph taken on July 14, 2005, by Elliot Endo

An earthquake, a plume and a very active glow...

Just prior to sunset at 20:54 last night there was a 3.2 magnitude earthquake at Mount St Helens, which was associated with a small ash plume and rock fall from the lavadome. As a result the glow from the lavadome was very active throughout the entire night!

Tuesday, July 05, 2005

A clear view of Mount St Helens

The weather has been clear over the last couple of nights and the US Forest Service Volcanocam has had good views of the incandescent glow from the lavadome on Mount St Helens. There was even a bright outburst indicating a rock fall from the lavadome on Sunday night.

Sunday, July 03, 2005

Deep impact hits comet

The NASA Deep Impact interceptor has just struck the comet Tempel 1 - direct hit!

Saturn moon riding the waves...

The latest raw images from the NASA Cassini spacecraft show one of moons causing some really interesting turbulence in Saturn's outer F-Ring. The short animation below consists of three sequential images taken on June 29, 2005 from 1,522,888 kilometers away.

Click Here