But, what about the resolution thing?
D7000 is 16.2 megapixels and D700 is 12.2 megapixels. Or is that more than compensated due to the sensor's size? meanining that if we take the percantage factor (full to 2/3) we end up with a total 18 megs on the D700? is that a reasonable analysis?
The cost to produce a wafer of semi conductors is fairly constant. The reason why computer chips keep getting less expensive is because they keep getting smaller, meaning that you can squeeze more chips out of a wafer. This is what has driven the so-called "Moore's Law" over the past decades.
That's not true for camera sensors. Since a DX or FX chip has to be exactly a certain size, the number of sensor chips per wafer stays constant. So, the cost of production does not go down as dramatically as with computer parts.
Once the sunk costs are down, there really isn't that much of a difference that extra pixels will make to effect the cost of the part. 12mp or 16mp, the sensor bed is etched in all at once.... there may extra tooling costs for the additional complexity, but again, the principle behind manufacturing the chips is the same in each instance.
So all told, a DX cvhip costs about $50USD to make a FX chip is about $500. The difference is practically the cost of a D3100. And as far as I am led to understand, all full frame chips must be "stitched" together during the manufacturing process, which keeps costs quite high.
There's also the matter of defect rate. If you average a certain number of defects per wafer, it's more costly doing the full frame chip run than for the DX chip because there are less chips to squeeze out per wafer.
The other thing is in the extra computing power that goes into a pro camera. Modern digital cameras are stuffed with circuitry... the D700 is bigger than a D7000 for exactly this reason. It focuses faster and more reliably because there are more brains driving the AF-system. More chips, more money.
If you dig through film cameras, there's a big difference in size between a Fm2 and an F5, even though they take the same film canister. All of of the extra size and cost of the F5 go towards the extra functionality... basically, if you want more, it costs more.
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