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Old Jul 17, 2003, 11:12 PM   #1
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Join Date: Jul 2003
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Default New digital camera purchase

Hi all,

I am a newbie to digital camera and is researching on which digital camera to buy.

Upon purchase of a camera, what defects can there be in the camera?

I only know of people saying about bad pixels. Exactly how do you check for them?

Any other defects? Maybe someone experienced can share a procedure he/she uses upon purchase of a camera to find any manufacturing defects.

Thank you all
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Old Jul 18, 2003, 12:45 AM   #2
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Posts: 212

When it comes to sensors, it's a little difficult to tell sometimes that the camera has a problem.

The first problem with pixels is the so called 'hot pixel'. It's a sensor point that has gone haywire and shows up in the photo as a single bright pixel. You will never notice one of these unless you are looking at an enlarged image (on either your monitor or in a print). You will most likely notice a hot pixel in photos of dark objects where the bright pixel stands out from the surrounding dark pixels. This is the point where you take the camera back and ask for a replacement.

The second problem with pixels is the 'dead pixel'. It is the opposite of a hot pixel in that instead of sending bright pixels to the image buffer, it sends no data. This would show up as a black spot in the image. You would most likely notice this kind of problem when shooting a light colored object like the sky or a white sheet of paper. Dead pixels are rampant. It is one of the byproducts of the level of miniaturization that has been achieved. For every CCD that is manufactured, a handful of pixels on the sensor are dead. Camera makers have found that the contents of a dead pixel can be interpolated from the four surrounding pixels (North, south, east, west) and that the value is more likely than not going to be correct to some margin of error. The upshot of all this is that you may actually never see a dead pixel on more expensive digicams unless an entire region of your CCD is dead. Cheaper digicams may not have the interpolation feature and may thus show some dead pixels.

As for other problems with the camera, there are any number of things that could go wrong with it, but a lot of that would be true if it were a film camera as well. Misaligned lens, loose electrical contacts, broken zoom/shutter/diaphragm, crashing software, etc. But these would be true on any modern camera.
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