Nikon D7000 Holding down shutter won't autofocus?

I just bought the Nikon D7000 as my first DSLR camera. I'm extremely new to this and have been reading through the manual/youtubing videos and trying to learn all of it's functions. I'm not sure exactly what I did but now when I hold down the shutter half way it doesn't autofocus. When I hold down the Autofocus button on the left side of the camera and try to move the dial to adjust the settings nothing happens at all whereas before I remember it would change the settings.

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What's your word about Nikon D5100?

Just bought used D5100, I can't test it yet. This is my second camera, my first was the Nikon D3100 but I had no time to explore it and in the end I sold it. Later I started to feel bad for selling it and desided to buy a new one, upper class. First I thought about Nikon D300 but I haven't got enough budget for that. Then I thought to buy D200 but it seemed too aged. And at the end I bought the D5100, what's your word about it?

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How To Make My Instagram Like My Tumblr Feed?

I'm 14, I have an iPhone 4s (the lighting sucks) and a Nikon D70, Which is too big to bring everywhere.

I want to make My Instagram look neat and organized and hipster but I don't want like a grunge or pale account, i just want it no filter, but good pictures
EG: @joannakuchta, @elizabethjanebishop, @cigarvette and @aliencreature
Their pictures look like they're from Tumblr, yet it's their own. I want that!

Do any of you know what type of adjustments or filter that can help me achieve this kind of feed? I know you need good lighting and a good set of colours to try to maintain.

I want my Instagram to show that I have a good life, lots of fun, such as travelling, food, fashion, music and art etc.: I'm good with food. My style is not completely off the rails like joanna, but its a decent, not much hipster tho, I have talent in piano and classic music, but my music taste is pretty much like arctic monkeys, Lana, Marina, The 1975 etcetc so hipster, and i have good art skills.

Can anyone give me some advice and what to do with my pictures to make it look like them? This would save my life haha

THANKS

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Why does the cost of camera, or the type of camera matter?

I use the Nikon D3100 myself, but some people I know use the things like the 60D canon, and more fancier cameras like the D7100. But the quality of some of the cheap camera's and expensive lense combo are doing very well. So, why is it that the more expensive camera's seem to matter at all, as long the quality is still great? I just really love my D3100, because it's small and easy to carry around, and it produces great quality picks. Wouldn't it seem that the bigger camera's are for more of fast speeds and fancy model shoots?

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