Digital cameras, spots on the sensor?

Here's a question for you digital camera users out there. Looking through the pictures from my recent California road trip, I noticed a few images that had spots in consistent locations in the frame. I assume that these spots are caused either by dust or flaws in the sensor. The picture below is an example. This picture is unretouched (except for reducing the size and marking the spots).<br><br> <br><br>The interesting thing about these spots is that they're translucent. (The blue sky shows through.) They're not black specs, which is what I might expect if they were dust. I noticed a few other frames, taken two days earlier, where the spots were larger and fainter, but still in the same locations. In the vast majority of my pictures, the spots are not visible at all. (You can only see them when the backgound is flawless blue sky.)<br><br>Anybody seen this sort of thing in their digital photos? My camera is a Canon Digital Rebel XT SLR. Like most digital SLR's, the Rebel XT has a way to clean the sensor if dust gets on it. I'll be trying this. But I thought I'd throw this out there to see if anybody else has seen something like this.

My camera is a Canon Digital Rebel XT SLR.

<br>Lowell, I don't have an answer to your question but I would like to know how you like your Rebel XT. I've been considering gettin one. So far are you happy with it? Is it small enough to fit in a pouch on a shoulder strap or does it require a chest pouch?

They look like water spots to me.<br><br>Could water have condensed in the camera (on the sensor) or inside the lens? I'd start by taking some test pics with another lens to try to determine the source.

<br>Lowell, I don't have an answer to your question but I would like to know how you like your Rebel XT. I've been considering gettin one. So far are you happy with it? Is it small enough to fit in a pouch on a shoulder strap or does it require a chest pouch?

<br><br>It requires a chest pouch. The camera is supposedly one of the smallest digital SLR's out there but, being an SLR, the lenses are pretty large. I bought the starter kit, which comes with a 18-55mm lens (equivalent to 29-88mm on a film camera). I have a few other Canon lenses already from my old EOS film camera. They work on the digital body; just multiply the focal length by 1.6.<br><br>So far, I'm quite happy with the camera. It has all the manual controls I need and the metering system is remarkably smart. I rarely need to do exposure compensation, which is something I'm always doing with my film camera. The camera is really good at exposing for detail in variable light conditions, conditions where my film cameras would typically give me a lot of dark shadows. It also seems to take good pictures in snow without exposure compensation. The only place I've found myself adjusting the exposure is in sunrise/sunset scenes, where the camera will try to give me detail in the shadows (resulting in washed out skies) when I want more saturation. Easy to fix--just stop down 2/3 or so.<br><br>Of course the best thing about a digital SLR if you're shooting action is that it takes pictures now. No "digital delay".<br><br>I've run through the procedure to clean dust off the sensor and I'll try some sample pictures when the sky clears. One thing that concerns me about digital SLR's is the posibility of dust contamination. The more you change lenses, the more likely this will occur. On the Rebel XT, you fix this by telling the camera to flip up the mirror, removing the lens, and blowing air into the body. Some digital SLR's actually employ some sort of ultrasonic mechanism to clean dust off the sensor.

Second the water spots call. <br><br>Ive had condensation inside Nikkor lens with elevation gained from warm muggy morning valley floors to higher cool bluebird afternoons show up on SLR slides. Overlake Photo was familiar with this before being digitaled out of business. Have several Enchantments day hike slids with the same deep blue spotted sky.

Thanks for the tips. I used a bulb thingy to blow the dust off the sensor and took a few pictures of blue sky this afternoon. I can't see any spots. Either it was condensation or I got the dust specks. If it was condensation, maybe it formed around dust, because the spots were in identical locations on pictures taken three days apart. We'll see if the problem comes back.<br><br>For Jeff: another observation about the Rebel XT. I run through batteries pretty quickly, so I always carry a couple extras. I've read in reviews that one of the things they did to shrink the XT body was to use a smaller battery. The batteries are pretty small (not a big burden to carry extras) but rather expensive.<br><br>I think battery life is directly related to the number of pixels you shoot. I've been using 500 MB flash cards and it seems like this size card is pretty much equal to a single XT battery. Shooting large, fine JPEGS (8 Mpix), that means about 150 photos per battery charge.