Is this what dust looks like?

[Radtech1]

I have a 3 week old 10d using a 28-135 IS lens. The once I put the lens on, I have NOT taken it off. On last nights batch of images, I saw some dark areas in the same place on all images. They are not black, just dark. They do not change with zoom, so I THINK I can rule out some lens problem. (Or can I?)

Is it possible that this is dust already? If so, how did it get in if the lens has not been off of the camera. Is that not a sealed system - for something as large as dust, I mean.

Anyone have a similar experience?

Radtech1

http://users.adelphia.net/~radtech1/Photos/Dust01.jpg

Full frame image.

http://users.adelphia.net/~radtech1/Photos/Dust02.jpg

Zoom on area.

http://users.adelphia.net/~radtech1/Photos/Dust03.jpg

Dark spots pointed out.

[ChrisNardone]

I think yes. Take a shot of a blue sky, then aim at a different spot of sky and take another picture. I guess to be safe repeat this with a different lens. If the spots are in the same place in each shot. It's dust.

[defordphoto]

Yup. Looks like dust bits. Crank the f-stop to max and then shoot the (clear) sky. Those dust boogies will become more defined.

[hmhm]

Yes, it's dust.

It's not a sealed system, because, well, light has to be able to get to the sensor. When you take the lens off, there's just the mirror sitting in front of the sensor, and that mirror swings out of the way whenever you take a picture.

My 10D came out of the box with some dust on the sensor (no extra charge).

Everybody will tell you to "shoot a picture of the sky", which is fine if you happen to have a daytime sky nearby, but to test for dust, you can just use the smallest aperture you have (f/22 or f/32) and point the camera at a wall or ceiling or something without much detail. If there is a little detail in the surface, just use a long exposure and shake the camera around a little bit during the exposure to smooth it out (the dust doesn't move, obviously, because it's on the sensor).
-harry

[who10]

Here's another example of verified dust... 100% crop of the affected area. In my case I had about five pictures with the same dark spot. Later on I looked at the sensor and sure enough, a spec of dust.

Used a squeeze ball type blower and cleared it right off (following the mirror lockup/cleaning guidelines).

http://haskellct.com/EE_Galleries/Gallery1/webguests/Dust.jpg


D60

[Derek Smith]

I don't understand, the sensor is 23mm x 15mm.

Dust is tiny - only parts of a mm across. If a tiny dust speck is sitting on the surface of the sensor, then it can only be covering a few pixels, and as it is immediately above the sensor, the shadow edges should be sharp and the dust spot should be black.

How come these blotches are huge and diffuse and grey?

If this is dust, it must be a good way in front of the sensor in order for its shadow to fan out and become a diffuse grey.

I have seen dust effects on a Nicon digital - they were tiny and jet black - exactly as you might expect.

So what can be going on here?

[dleewo]

Derek Smith wrote:
I don't understand, the sensor is 23mm x 15mm.

Dust is tiny - only parts of a mm across. If a tiny dust speck is sitting on the surface of the sensor, then it can only be covering a few pixels, and as it is immediately above the sensor, the shadow edges should be sharp and the dust spot should be black.

How come these blotches are huge and diffuse and grey?



Isn't there an anti-aliasing filter in front of the actual sensor. I don't know how far in front it is, but maybe that might account for the non-sharp edges.

[who10]

There's a good illustration and description of the CMOS/HighpassFilter sandwich from the DPreview of the D60 (same construction in the 10D) at this link:

http://www.dpreview.com/reviews/canoneosd60/page8.asp

Explains why the dust affect looks different on D60/10D vs Nikon and others.


David

[martcol]

Certainly looks like dust to me! First - Bad luck; second - don't panic.

I have had dust problems and I have a few spots now. However, it rarely interferes with my pictures and if it does a quick fiddle in PS takes care of it.

Search the forum for dust and you'll see plenty of discussion about it and especially, cleaning it. I have been so careful with my 10 and only change lens reluctantly. That's a bit of a downer when you're using a system partly because of the potential for using interchangeable lenses! If I'm in an environment where there is any hint of dust or wind or dust & wind, I won't change the lens. I've also had a stab at cleaning and have never had totally satisfactory results. I've sent it to Canon 3 times and they have done no better than me!

So, I just put up with it and try not to let it prevent me from enjoying my kit. Of course, dust spots can be much worse than the examples posted here and then you have to do something. It's partly down to individual tollerance levels!

Martin

[scottbergerphoto]

Sorry for the late response. I just noticed this topic. I just shot a bunch of city skyline pictures last weekend and got similiar results. I checked my lens and found a dried waterspot on my UV Filter. I cleaned the filter and the problen went with it. It would seem that dust or debris anywhere in the optical path could produce similiar results.

[ssim]

I had this happen to me within a few days of getting my 10D. At first I was panic stricken but cleaning the image sensor is quite easy.

I've also found that make sure to change your lenses in an area that is not windy or doesn't have alot of dust in the air (easier said than done).

These spots can be easily cloned out in PS.

[pwagner]

I managed to blow the dust off my sensor. Seemed a lot easier than "taking it in" and a lot less risky than cleaning it myself.