From myself I will say - this is my first DSLR, on the whole I am very satisfied, given the price of the device and its segment, there is nothing to complain about, everything is done well. I compared the noise with the D90 - the D90 loses! The matrix is in the D3100 Expeed 2, it is the same in 5100 and 7000. So there will be no difference in image quality in the D3100-D7000 range, the difference is only in the extra. functions, control, and maybe 7000 have less noise. If you realize that you have grown out of this device or you just want something different and better, then TAKE FULL-FRAME IMMEDIATELY! Because changing crop to crop is not a particularly productive business. I recently bought a 50mm 1.4 lens, I'm learning to work with it, the picture is completely different! By the way, the whale 18-55 lens is not a bad one, for its price it does everything it can)
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