Now the industry of amateur DSLRs is such that devices of the same level: nikon, canon, sony, pentax for an AMATEUR will be almost identical. It is unlikely that you will see a big difference in quality, especially in jpeg. Canon - more ascetic, more reportage, as it were; the best video, so if you are primarily into video shooting, then I advise canons. Sony has the most innovations, but the most raw are newcomers to the mirror sphere, who, however, are actively mastering it. Pentax - thinking, which gives an artistic effect, is specific. Nikon is quite versatile, but also without specifics, IMHO. In general, devices of the amateur segment are all universal, especially for shooting in Auto or P. Don't be techno-fetish. Remember also that in the world of DSLRs, lenses matter more. Cameras are replaced every 2-3 years and become morally obsolete, and their "eyes" stay on the market for 5-10 years or more. Take according to subjective feeling. In general: D5100 is a model for a beginner who will not limit himself to periodic shooting and / or family use of the device, and will not seriously consider photography as a hobby. Then it's easier for you to take the D3100. The device is also excellent among its peers, with excellent quality. If you want to get down to business seriously, but still a beginner and your device is the first DSLR, then the 5100 is an ideal choice. Potential, excellent quality, a lot of possibilities and nothing more. However, I advise even beginners to pay extra 5t. R. and take 5100, you will definitely gain, but you will not lose;) The D7000 is much more expensive, and it is for enthusiasts who have already gone through their first DSLRs and who shoot a lot and for a long time - a strong body is important to them, and a screwdriver (and they know perfectly well what it is :)), and an excellent viewfinder. Well, additional buttons, of course. The average hobbyist will rarely use it, and the price is almost 20higher, meanwhile. So don't bother. In addition, the 7000 is no longer new, and the 5100 is only six months old. In its segment, the D5100 is one of the best and most interesting cameras, a fact.
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