Dust on the sensor – impossible to clean (example: 5d MkII)

In fact, the dust what You can clean in home conditions, or without disassembling the whole camera at any camera is the dust from the surface of the low-pass filter.

There are many methods for cleaning, for myself i prefer blowing with compressed air, and if this is ot enough, then a wet cleaning with alcohol, some cotton swabs, and after this, as a last step the sweeping with a microfiber cloth on a wood stick (the plane end of a wood spoon from the coffeshops). The very tough dust pieces can be moved (dry) with a small brush with plastic bristles (which the artists use) + pressurized air.

But always under strict visual control of a stereo microscope with a 10x / 20x magnifying power.

Why is this important?

Because You have to be sure, that the “particle” which You are hunting on the surface is:
not a small scratch, which is better not to scrape (You can damage definitely the surface)
– it is really on that outer surface.

It happened to me a few times before, that after cleaning, and controlling the surface with a strong LED-light and a lupe, there was dust on the test picture. This is mostly by the cameras which have on active dust removing system.

Here is the explanation, why:

Example 1, the good old 5d (Mk I)

5d Mk1 low pass filter
(from the Canon EOS 5d white paper)

Here the low pass filter is glued together in a single sheet, and it is mounted on the front of the sensor with no possibility of penetrating of air (with dust). No moving parts, just two parts in contact.

Example 2, the modern 5d MkII, with integrated ultrasonic cleaning system

5dMk2 sensor  5dMk2 low pass filter  5dMk2 integrated cleaning system
(from the Canon EOS 5d Mark II white paper)

As You see, the ultrasonic cleaning system vibrates only the front sheet – that means, that can not be glued together with the others. The result is, that some air and dust can penetrate under the first plate.

Yes, yes of course, there is a sealing frame there – but in the practice the dust is there inside.

And You can’t get it out from there.

What helps You in this case the microscope? Microscopes have a very thin depth of field. So, if You set the microscope on the surface of the outer filter, only the dust on it will be sharp – the rest will be blurred. And after this, You can check the dust under the outer plate turning the focus to the deeper layer. (I will make some pictures later) (once…)

The microscope which I use now is this:


It has a working distance of 100mm from the object – perfect for sensor cleaning, and even for soldering on the PCB-s (for 150 EUR).

Yesterday I’ve seen internal dust on a 40d too.

About canonrepair

Ruzsa János. Amatőr fotós, Canon DSLR váz. Amateur photographer. Canon DSLR user.
This entry was posted in Canon camera, General topics. Bookmark the permalink.

11 Responses to Dust on the sensor – impossible to clean (example: 5d MkII)

  1. Baldvin Baldvinsson says:

    Hi there I got scratches on my CMOS and I was told it could not be cleaned. I have taken a lot of photos since then and the scratches does not seems to affect the quality of the photo. But I know it does. Scratches changes lights but I am wondering is there a way to change this front filter of the CMOS or would I have to buy me a new Sensor.

    You say you use compressed air for cleaning I wonder because I have been warned about that. Always some liquid there so if you do I like to know how you use it. Do you blow out the can for awhile to get rid of the liquid or.

    Baldvin Baldvinsson

    • canonrepair says:

      Hi Baldvin,

      when I say compressed air, that means REALLY compressed air, produced by a compressor, NOT a spraycan, which is NEVER air, rather some gases like propane or R134a (the gas in the airconditioning systems) in liquid form. I have a compressor without oil (PTFE piston), and some filters in the supply line.
      Normal pressurized air contains only some water, but can be filtered out, respectively the normal air has also water, ca 40 % vapour at normal conditions – thats not a problem.
      The best would be pressurized Nitrogen (200bar bottles) with a regulator, that contains 0% water – but it is more expensive.

      • Baldvin Baldvinsson says:

        Thanks for your answer.
        So I can use my compressor for this work. But what about the scratches on my sensor or is it just some filter front of the Sensor you can take off..

        Kind regards. Baldvin

  2. bluechip says:

    Thanks for sharing such a nice information…
    Good job..
    Modern 5D

  3. Mai Calapardo says:

    Do you think it is worth replacing the CMOS of my Canon 5d mark ii or I’d rather buy a Canon 6d? I use it mostly for shooting videos. Mine currently has 26000+ actuations from 2 years of use.

    Many thanks

  4. Mai Calapardo says:

    I am from the Philippines. When you mention that your sensor is not perfect, what do you mean by that? Can you provide me a quote for that. You can send me a private email at maicalapardo@gmail.com. Thank you very much sir.

  5. Mai Calapardo says:

    Hello sir!
    Can you please help me tell what are these? They don’t seem to be just dusts. Taken from Canon 5d Mark II. The rest of the features are working just fine. Only these specks are bothering me and they too appear in all photos and videos. Also visible from the viewfinder when maximized by 5x or 10x. Please sir, kindly tell me what causes these. Thank you very much.

    • canonrepair says:

      i think they are some scratches on the antireflective coating, or some grease on the surface. You should check it under a microscope.
      I have a 5d Mark II sensor, taken out from a damaged camera, which is not perfect, but much better, then this. if You are interested, write me a mail. Which country are You from?

  6. Szatmári Ferenc says:

    > (I will make some pictures later)
    I’m waiting for them…

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