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Dust on CMOS Sensor

old timer 13 55 1 Scotland
3 Dec 2004 7:42AM
As some may know, about 10 days ago I became the proud possessor of a Canon 20D. At first I didn't notice, until Jouko (jolli) brought to my attention the fact that there were marks on some of the shots I was uploading, and these were in a constant position. I carried out a test, and it appears that there are indeed defects present - the result can be seen HERE . Most of these are not significant, but the linear one at top right shows up as a slightly darker patch on a clear area of light colour such as sky - no problem to clone out, but a defect nonetheless. On other types of pic no problem is visible.

Never having used a DSLR before I'm not sure whether or not this can be accepted as just a fact of life. If it wasn't a brand new camera I wouldn't be giving it a second thought, but bearing in mind that it's only 10 days old should I be contacting the supplier?


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Just Jas Plus
16 26.2k 1 England
3 Dec 2004 7:46AM
Yes! This number of defects is unacceptable.

stevie Plus
14 1.2k 2 United Kingdom
3 Dec 2004 8:08AM
Hi Jim - I just wish my sensor was this clean! I can see that things aren't perfect but having owned a 10D for 18 months dust on the sensor is a fact of DSLR life. Some of my small-aperture Lake District landscape shots (for example) have quite an alarming number of dust marks on them and cloning them out is an almost standard part of post-image processing. Cleaning the sensor (see several threads) is effective but sadly, only temporary. I'd be interested to see what others say about this.
csurry 16 9.2k 92
3 Dec 2004 8:18AM
Boy Jim, those big red dots must be annoying Wink)
tezza 14 569 United Kingdom
3 Dec 2004 8:22AM

I had a similar problem with my new Digital SLR in April this year but got mine replaced by taking it back to the shop. Mine dots were what are known as hot pixels, in that I got a small cluster of red ones when a picture was taken with a lens cap on the camera and I viewed in on screen at 'view pixel' size.

I've looked at yours Jim but they do seem to be a bit regular in size to be dust, so do wonder if you too have something similar to what I had. Worth doing the test above and letting us know what you get.

Another thing is at small apertures, you have to make sure that your lens and front filters are spotlessly clean Steve. They too have made some members get the swabs out on their sensors when infact there was no need.

kidda 16 277
3 Dec 2004 8:46AM
I wish my 20d was that clean! mine was a bit worse than that after 2 weeks I gave it a good blow with a rocket blower and I'm down to about 3 spots.
See this SITE for info on cleaning etc.
old timer 13 55 1 Scotland
3 Dec 2004 9:02AM
This has all been very helpful indeed. I'm in little doubt that the problem is dust, and definitely not hot pixels, and as I suspected would be the case it appears that it's almost inevitable with a DSLR. I'd be reluctant to return it to the supplier for two reasons:

1) It would inevitably recur in any case
2) I'd be cameraless, as I've already sold my previous camera

It's not bad enough to need me to clean the sensor as yet, but it sounds as if it's only a matter of time until I will need to do it.
kidda 16 277
3 Dec 2004 9:11AM
Yep I'm new to a DSLR and must admit I was suprised how quickly it attracted the dust, but I guess with that mirror slapping around at 5fps its going to sweep any dust around that is there.

Im going to stick with the rocket blower until it gets bad then probably wipe it with the coperhill sensor swipe (seems to be what most use to good effect)
strawman 14 22.1k 16 United Kingdom
3 Dec 2004 9:25AM
I have survived with blower cleaning so far. I bought my 300D in January.
UserRemoved 13 6.2k 1
3 Dec 2004 9:27AM
Its the electrostatic charge that effectively means you have a dust magnet!

You could always get s Sigma SD9/10 - we have a dust shield! Well, OK, it doesn't stop all the dust - just the larger bits, and still needs cleaning in its own right!
tezza 14 569 United Kingdom
5 Dec 2004 10:43AM
As markulous says it's an electorstatic dust magnet which ever brand you have. So the biggest tip is to ALWAYS turn off the camera whilst changing lens. Leave its power on at your own peril!


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