How common are hot pixels on new cameras?!
I read that people may check up to 5 cameras at stores to actually find a perfect one, is this true? so how commons is this? what is the chance of getting a new camera with one or two hot pixels? will you ignore it?
They're very common — to the point that I wouldn't bother to check in advance. This will be especially true for longer exposures, as the sensor heats up. So, I just assume they're likely and plan to run the built-in pixel mapping function if I notice any.
Or, if I were to shoot RAW all the time, I'd wouldn't worry about it at all, since most RAW converters have their own feature (usually, automatic and on by default) to map out stuck pixels. If your preferred converter happens to not have this feature, you could use Pixel Fixer on your RAW files.)
Since I do shoot in JPEG, if I'm buying a camera that doesn't have pixel mapping as a user-accessible feature, I make sure I've planned for the possibility of a couple of weeks turn-around from a repair center. (I know Olympus and Pentax cameras have the feature; not sure of any others. There's a common belief that Canon cameras do it when cleaning the sensor, but this has been debunked as a myth.)
A lit-up hot pixel can be distracting and annoying, but once mapped out, the impact is something less than a 0.0001% loss of resolution.
Well, as people have pointed out, they are very common. Heck, 1 bad pixel in 1 million pixels is an error of 0.001% -> i.e. tiny.
Now in most cases hot or dead pixels will be mapped out by the camera's firmware of by the RAW editor and should not cause any problems. In this respect, it can also be quite difficult to find a hot pixel as you would need a way of interpreting the RAW data without any modification (rules out Canon's DPP and Lightroom for example).
In practice, if you have a hot pixel that causes issues you can always send in the camera under warranty - the manufacturer will then either map the hot pixels out of replace the appropriate part.
I've had 4 different models of dSLRs and a couple fixed lens digital cams (Fuji X100 to original Canon 5D to Canon 1D4).
I've yet to find a hot pixel on any of them.
Maybe I'm just extraordinarily lucky. My lenses don't back-focus, either.
