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Old 14-02-2010, 09:10 AM
solissydney (Ken)
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Cmos cleaning, or not?

I removed the IR filter from my Canon 5D and is waiting for a replacement UV/IR filter to arrive. The CMOS surface is not perfect as can be seen on the attached image. I don't believe I caused the faults on the surface when I took it apart. I tend to believe the scratches would not be noticeable once the new filter is installed. But just in case they do.
I have researched the subject of cleaning the CMOS on the web at lengths . It seems to me that one need to spend well over $100.00 for a cleaning kit from say, Delkin Devices, or make an attempt yourself. I could, for instance, in my case, practice on the filter I removed using, for example, Methanol. But the most critical part appears to be the medium that is to be in contact with the CMOS surface.
Has anyone been there and done that or made an attempt?
Ken
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Old 14-02-2010, 12:23 PM
solissydney (Ken)
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CMOS Cleaning

The difference between Methylated Spirit and Methanol is that Methanol has a smaller Molecule. Big deal?
As soon as I can get my hands on some Methanol I shall find out whether it leaves behind a greasy substance like Methylated Spirit does.
Tried several Chemists.

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Old 14-02-2010, 04:03 PM
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Methylated spirits is essentially ethyl alcohol C2H5OH. It has added to it a small amount of methyl alcohol CH3OH to make it undrinkable. It also has a small amount of pyridene added which gives it the smell (stink?) and also added to the poisonous denaturing of the spirit. The pyridene does not evaporate easily (b.pt. ~115C) and also leaves a film. Methanol boils at ~65C and ethanol ~78C.
Pure methanol and pure ethanol will both evaporate cleanly. Pure ethanol is hard to get because of government regulations and excise duties. Vodka might go close , but then......
Isopropanol is a good cleaning reagent used for lenses but I dunno about micro-chips. My guess though is that it would be OK.
Robert
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Old 14-02-2010, 06:22 PM
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I use acetone, and found less residue than all others.

Theo
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Old 15-02-2010, 08:20 AM
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Yes, acetone is also available pure and evaporates cleanly. But be careful near plastics. Many are susceptible.
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Old 15-02-2010, 09:21 AM
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Ken the filters in front and the CMOS, are tougher than lead to believe.

You have to be brave, and go for it, I did and it worked fine.

However there is a risk involved, and as mentioned Acetone will destroy and surrounding plastic in which the filter is housed.

Leon
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Old 15-02-2010, 09:37 AM
solissydney (Ken)
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I gave away the idea of Methanol,( too difficult to locate for most, comes in 1 liter can min, used for drag racing instead of petrol) after I purchased a pack of Inca Screen protectors for camera's. It comes with three stick-on sheets, one wet-wipe and one dry-wipe used for preparing the screens before installation of the clear plastic protectors. The wet-wipe, unlike Acetone and Isopropanol, leaves no residue. To test, place a few drops on clear glass or plastic and let evaporate. My camera was filthy on the inside so I decided to give it a good vacuum, see image. It did wonders, The CMOS, I found out was also very dirty. By applying some drops squeezed out of the wet-wipe onto the dry-wipe I began wiping the CMOS however, there were too much liquid on the dry-wipe so I resorted to using the dry-wipe with one finger in order to remove the excess liquid. This took some time as the dry-wipe was not all that absorbent. But all went well, with no marks or scratches on the CMOS, the camera is now clean as a whistle on the inside.
Next time I proceed to do that I will use just one drop or less, off the wet-wipe.
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Old 15-02-2010, 12:28 PM
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Acetone leaves no residue, unless the wipe being used is dirty.

Theo
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Old 15-02-2010, 01:24 PM
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Ken there is one question i would like to ask.

You said the CMOS was drity, well this is not really possible, after manufacture as the front filter is there to protect the CMOS.

However if you remove the front filter, and do not cover the CMOS, or place it into a new sipped sandwich bag, or leave it open it will get dust.

Ken i have done 3 5d's, exactly to what you have done, there is no chance of dust or any other particles of dirt getting into the CMOS unless you left it exposed after removal.

So I wonder why yours was so dirty as you said

Leon
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