Help me diagnose a spot

[devwild]

Just today I received my first SLR camera, a Digital Rebel XT. After spending some time admiring the spectactular quality and flexibility in comparison to my previous camera (Fuji S602z) I noticed a major issue with my sky shots as the sun went down and I started tweaking exposure. As I went back through my previous photos and examined them more closely, I found the problem was there from the moment I opened the package.

The problem? A big spot on the photo. The spot does not move based on zoom, there is no visible dust on the sensor (or lens, or in viewfinder). Any cleaning attempts have been futile. The spot seems there to stay

The following is a picture, actual size from an 8MP original. The image has been brightened to make it more obvious at this size, but is quite obvious in the original as well..


So, what do you guys think? Is it some barely visible smudge on the sensor? Is it a defect in the sensor? If I have to pay for shipping to repair replace a brand new and expensive camera for a defect that shouldn't have made it past Q&A, I will be... quite unhappy.

Thanks, and sorry my introduction to your forum is due to a problem. Hopefully my future posts will be more positive.

dev*

[Lionheart]

but if cleaning attempts haven't removed it, then I don't know what it is. I get those all the time, but blowing off the sensor with dry gentle air with a vacuum source near the lens mount has always done the trick for me. Bring it back to the shop and get an exchange or send it in to Canon USA in Costa Mesa, CA. I'd be seriously PO'd too. Canon occasionally does ship defective products to market-I had my first EOS-1D shipped to me with the mirror locked up and stuck there. Maybe defective pixels on the sensor?

[mjs1973]

Welcome to the forum. My first thought was dust also. I have had that same spot before, and like Lionheart said, dry air should blow that off of there. I had to use several blasts from my rocket blower to get it off of mine. I have heard of others having this same problem, staring with their first pic as well.

How did you try to clean it?

[another view]

Yep, dust. It's usually not visible unless it's really bad; that's only happened to me once that I recall. Being careful changing lenses will take care of most of the problems.

I'm also wondering how you cleaned your sensor. There are a lot of ways that I've seen people do it, and using "cleaning mode" with a Giottos rocket air blower. Cleaning mode on my Fuji will make sure the sensor isn't charged which will make it almost impossible to clean. I have to use an AC adapter and a couple of buttons while turning it on. This locks up the mirror and opens the shutter, exposing the sensor. Best to do it pointing down so gravity works to your advantage too.

[devwild]

I used cleaning mode and a gentle attempt with a blower.

I haven't ever seen a spec this large from a dust particle, certainly not directly on the sensor (a piece of dust that large on the sensor would definitely be visible... you have to realize, this is a 2-3 pixel diameter spot even on the LCD review at no zoom ).

There does however seem to be a radial blur to the spot, from center-point to outer edge (bottom right to top left in this case). Also the spot fades the larger the aperature used in the shot. This would seem to imply that it is dust somewhere in front of the sensor, such as on the back of the lens (which I have examined with a magnifying glass even). Perhaps even inside the lens assembly, though I don't have another lens to swap with yet.

I guess I'll take more time to mess with it, see if I can pick up a rocket blower somewhere tonight... I definitely don't want to have to ship the camera to canon... The lens wouldn't be a big deal.

Thanks,
dev*

Edit: never mind, it was on the sensor (filter). It took some effort to get it off, and in the process I ended up with a couple more specs. This is going to be a handfull I see. Bluh, I'll mess with it later... I didn't think my apt had gotten that dusty but apparently so. ;)

[devwild]

Ah, finally got my rocket blower along with some other supplies in the mail, and with a number of tries, was finally able to make my camera dust free. Many thanks for the recommendation, and I might add I'm glad I got the large model, cause even with that it took repeated effort

Thanks
dev*