tboy said:
Rock: the problem with that salesmen is that while the pixels are smaller, that means the image is smoother. Meaning there are more "dots" to make up the image. Just like a printed photograph or billboard. The more dots there are, the image is sharper and more precise.
Just like with HD tvs: a 1080 tv produces a better image than a 720.
for the record: a 1000 MP image is about 1000x smoother and sharper and crisp, than a 12 mp image.....anyone who tells you different doesn't know his ass from a hole in the ground.
Believe it or not, that salesman DOES know what he is talking about - smaller photosites (below a certain size) have noise issues because each photosite is capturing fewer photons. This is well documented on photography sites such as dpreview.com.
And besides, beyond a certain point, absolute megapixels is meaningless - if one had a 1000000000 MP sensor, would that be 'better', or would all that data simply be wasted? Engineering-wise, it is important to consider one's final output medium to make a good choice as to how much data you really need to scan off your sensor (and store, and manipulate, etc).
For instance, if we use HDTVs as an example, though anyone can see that 1080 is a bigger number than 720 and thus it is a simple comparison, whether that number is useful to you actually depends greatly on
1. How big your screen is and
2. How far away you sit when you watch it.
For a 50" screen, one would have to sit quite close, at around 6.5 feet away, to fully get the benefits of 1080p. If one sits further at say around 10 feet away or more, one's retina simply doesn't have the cone/rod density to distinguish between 720p and 1080p on a 50" screen. There are many graphs available on the internet to show this relationship between screensize, viewing distance, and resolution, here's one:
http://www.soundandvisionmag.com/hitech/1137
Which means that when 2k resolution and 4k resolution sets start becoming common, you'll know that they really aren't necessary unless you have one heck of a huge display, or you like sitting only 2 or 3 feet from your screen.
However, I'm certain there will be lots of people bragging about how they have a 32" screen that is 2k resolution, and yet they sit 10 feet away to watch it.
Similarly, camera sensor designers are caught in what is called the 'megapixel' race, where seemingly the ONLY metric the common consumer focuses on is the number of megapixels... to the detriment of other sensor metrics (such as dynamic range and low noise at high ISO).
In general, anything around 8 to 12 MP should be more than most casual shooters would ever need for cropping and editing, before the small size of the individual photosites causes a lot of noise at high ISOs.
For my money, it is more useful to find good high ISO performance in a DSLR - being able to shoot at high ISOs like 3200, 6400 and higher, with low noise, really helps to take pictures in challenging conditions (indoors, low light, etc). Also, accurate focus in low-light conditions is also very useful - it is quite frustrating to have the focus hunting back and forth. Higher-end cameras have better contrast-detection systems and can focus better in low light but they are $$$.
Anyways, hope this helps SOMEONE out there...so that my hours and hours of reading photography sites isn't completely wasted
