Canon's unsuccessful sensor cleaning on a 5D Mark IV

[DavidR]

Dear all
Today I cleaned the sensors on my two 5D2 cameras. I had originally thought they were both pretty clean but I discovered a large number (c.30) spots on one sensor whilst editing in Lightroom. The reason I discovered the spots was that I used the Prolost dehaze plug-in for the first time and when I set it to 100% the spots appeared!
So today I used the dehaze feature to check my cleaning and it proved a marvellous help in checking where the spots were and whether I had got rid of them.

 

[Mt Spokane Photography]

Canon has agreed to take the camera back and perform a cleaning service again. Canon is also paying the shipping costs.

I certainly hope for a better result. Is it true that Canon does only a dry cleaning of their sensors?

If I end up going for a wet cleaning on my own, I plan to use Visible Dust swabs (green) and Dust Patrol's Gamma Optical Cleaning Fluid.

For those who wish to share how many swabs they use for a wet cleaning to get their sensors fully clean, I'd be curious to know your number. I went through five to get my 5D Mark III clean, but the first time I tried a wet cleaning, I used around 15 swabs. It was a bit of a learning curve for me.

Incidentally, the attached photo for this post was taken at f/22. In the past, I used f/32, but I'll be all right with a sensor that looks clean at f/22.

If there is oil or some material that requires a wet cleaning, they will do it, but they do not wet clean a sensor by default. Something definitely smeared on the sensor, dust particles don't do that, so oil or a botched wet cleaning.

I do wet clean my sensors as a last resort, I never had to wet clean my 5D MK III, but did my MK II a few times. My Rocket blower took care of the MK III. I have not noticed any issue with my MK IV or SL2, but I'm pretty tolerant of a few dust particles as long as hey are not gross.

 

[Jopa]

What was it cleaned with a sand blaster?

Pressure washer with some soap most likely.

I bet it's not that funny for the owner though

They saw these tutorial: https://www.youtube.com/watch?v=lrdkFXsr5Us

This is nuts!!! ;D

 

[Talys]

Hi, Talys.

I've not had much luck with camera shops. They've told me dirty sensors were clean (two different shops). I've had estimates from other places of up to $100.

That's why I cleaned my T3i and 5D Mark III. At just under $65 for Canon to do the service, I thought I'd try it out for the 5D Mark IV. I'll shoot at f/8 to f/20 with some frequency, so having a sensor with no spots at smaller apertures is important for me. I can use the Mark III in the meantime.

For those of you who do your own cleaning, you're getting a fully clean sensor at f/22 or smaller aperture?

Holy smokes. That's insane!

Locally here, there's one store that has a frequent shopper thing, and every 10th visit or something, they'll give you a free sensor cleaning. Not that I've ever tried it; I just do it myself.

But -- there should be no difference between f/22 or f/32. Dust is dust, and it will block light from reaching the sensor, whether you're shooting at f/1.4 or f/32. Because it's right on the sensor, there's no depth of field or focus issue. It's actually blocking light from reaching the sensor, and therefore, assuming noise reduction, antialiasing and all that is turned off, the raw data should have clear dark spots.

The only reason you want to set it to a small aperture is so that you can increase the shutter speed to a very slow shutter speed (you could use an ND filter instead). The only reason you want a very slow shutter speed is so that you can move the camera around, so that you're not photographing (recording) imperfections in your drywall, cardboard, white backdrop, or whatever you're using.

A sensor loupe (or some other magnifier) might be helpful in diagnosis.

Not that I'm an expert in this, so if I'm wrong, someone please correct me

 

[SecureGSM]

Hi Talys,

Dust cannot be detected when shooting with F1.4 apertures.
You need to stop down to F11 at least to see the dust clearly. That's due to physics of light and how it moves around avoiding obstacles. Ideally you would like to stop down and use long exposure while pointing at a white wall and giving your camera a circular motion handheld to blur background features.

But -- there should be no difference between f/22 or f/32. Dust is dust, and it will block light from reaching the sensor, whether you're shooting at f/1.4 or f/32. Because it's right on the sensor, there's no depth of field or focus issue. It's actually blocking light from reaching the sensor, and therefore, assuming noise reduction, antialiasing and all that is turned off, the raw data should have clear dark spots.

The only reason you want to set it to a small aperture is so that you can increase the shutter speed to a very slow shutter speed (you could use an ND filter instead). The only reason you want a very slow shutter speed is so that you can move the camera around, so that you're not photographing (recording) imperfections in your drywall, cardboard, white backdrop, or whatever you're using.

Not that I'm an expert in this, so if I'm wrong, someone please correct me

 

[pwp]

Here's the perfect sensor clean instruction video:
https://www.youtube.com/watch?v=lrdkFXsr5Us
The results would deliver a perfectly clean sensor every time.

-pw

 

[Talys]

Hi Talys,

Dust cannot be detected when shooting with F1.4 apertures.
You need to stop down to F11 at least to see the dust clearly. That's due to physics of light and how it moves around avoiding obstacles. Ideally you would like to stop down and use long exposure while pointing at a white wall and giving your camera a circular motion handheld to blur background features.

Interesting. That's exactly what I do, but I was unaware that it was undetectable at wide apertures. I've never tried it, because you need the smaller aperture to give yourself time to do the circular motion that you describe. Usually, I just set it to f/22, 2 seconds -- or thereabouts.

 

[notapro]

If anyone is still interested or curious, this is the sensor after it's second visit to Canon's repair center (this time it was sent to the Virginia location).

I'm glad to have a Mark III to use while the Mark IV is out of service.

I took another photo which shows some degree of improvement over the previous cleaning. Canon requested this image so that their technicians can use it to guide them in the sensor's third cleaning.

Canon is paying for shipping both ways and has not charged anything additional.

 

[Mt Spokane Photography]

Wow, Canon needs to do a wet cleaning, the dirt looks baked on. A lot of the smears are still there. Canon does not need the photo to guide them, they should be taking their own, before and after until its clean.

 

[ejenner]

After 10 goes you might get a new camera.

I've always cleaned my own. But I have had to get less anal about getting absolutely everything off.

For those of you who do your own cleaning, you're getting a fully clean sensor at f/22 or smaller aperture?

I used to try and it drove me nuts, now I no longer aim for a 100% clean sensor at f22. If I have 2-3 small and light spots visible at f22, then I call it good. Those will generally be very light at f16 and if they are in the sky I just heal in PS. I always check my images anyway as you never know when you might get a spot, even if it was perfectly clean before shooting.

Since using the gel pen I have found it much easier to get to something which is really not going to show up at f16.

I think some people, even shooting landscapes at f16, can get a little too anal about the odd light spot (the OP's sensor is IMO 'trash' right now though).

 

[Ryananthony]

Just clean the sensor yourself. How long is your camera going to be out of commission for something that will take you 5 minutes at home.

 

[ejenner]

But -- there should be no difference between f/22 or f/32. Dust is dust, and it will block light from reaching the sensor, whether you're shooting at f/1.4 or f/32. Because it's right on the sensor, there's no depth of field or focus issue. It's actually blocking light from reaching the sensor, and therefore, assuming noise reduction, antialiasing and all that is turned off, the raw data should have clear dark spots.

This would be the case IF the dust was 'right on the sensor', but it isn't. You have a couple of mm of glass between the surface the dust is on and the actual sensor pixels.

Just in case you are interested:

https://wordpress.lensrentals.com/blog/2014/06/sensor-stack-thickness-when-does-it-matter/

 

[Mt Spokane Photography]

But -- there should be no difference between f/22 or f/32. Dust is dust, and it will block light from reaching the sensor, whether you're shooting at f/1.4 or f/32. Because it's right on the sensor, there's no depth of field or focus issue. It's actually blocking light from reaching the sensor, and therefore, assuming noise reduction, antialiasing and all that is turned off, the raw data should have clear dark spots.

This would be the case IF the dust was 'right on the sensor', but it isn't. You have several mm of glass between the surface the dust is on and the actual sensor pixels.

Yes, its been well established since the first DSLR's that dust on the sensor assembly can be seen best by lighting it thru a small aperture of the lens. That creates more distinct shadows from the smears and dust particles.

 

[notapro]

I received my camera today, back from its third trip to Canon.

The "service details" section on the note from Canon says that the sensor was ". . . scratched and had dust on it. The CMOS assembly was replaced".

I am curious as to whether it was felt that a cleaning would not have removed the dust. I didn't notice any obvious scratches in the photos I posted previously in this thread. It's nice that Canon replaced the CMOS assembly and that they did so as a courtesy.

The new sensor (glass above it) isn't perfect, but it's good enough for now. The attached image shows some of the dust spots underlined by white lines. The image was taken at f/22, ISO 100, 2.5 seconds (manual focus, with the focus set at "infinity"). After pulling the RAW image into Photoshop, "Auto contrast" was performed, and I drew in the white underlines.

I took a couple of "regular" photos (not of the sort I'd use to check for dust) of my place (indoors) at f/22 and f/16. Only a couple of spots were visible with relatively careful inspection. They're the sort of spots that one might see in a photo of a clear blue sky, easily removed in post-processing. In practice, then, I'm fine with the sensor as it is currently.

I've cleaned sensors myself (as Ryananthony suggests in this thread), but given the $64.44 price (including shipping) for Canon to do the cleaning, I was curious about how things would turn out. I have a 5D Mark III, so being without the Mark IV for a while wasn't burdensome.

I credit Canon for taking action to help me with my camera, especially since I'm just a regular user, not someone who uses their professional services (CPS).

 

[Mt Spokane Photography]

All sensors have dust, a few seconds after cleaning, it settles almost immediately. Dust in the air is rated in millions of particles per cubic meter, even super clean rooms have some dust.

So, with a sensor, its more about objectionable dust, large particles in excessive numbers. The tiny particles are too small to be seen, but if there is oil or lube on the sensor, they collect into a nasty mess.

The dirt smeared on the sensor and the scratches look like they were caused by the dry cleaning technique. I had thought that amount of dirt was a thing of the past, which makes me wonder if it was a mixture of dust and lube.

 

[ejenner]

Nice that they realize they completely f**ked up the sensor. I guess not quite the 10 goes I predicted, 3 and a new sensor.

Yea, I've meticulously cleaned a sensor, then one shutter cycle and you have 3 new spots. You can keep doing that forever if you use your camera in less than perfect weather.

 

[YuengLinger]

Happy ending! Thanks for following up to let us know Canon treated you right after the back and forth.