Cant decide, now i have Nikon d7000, with 18-105mm starting lenses, should i buy FX Nikon D610 body only with basic lenses, or just upgrade my camera with better lenses, and later buy fx body? Im looking forward to buy Nikon AF-S Nikkor 16-35mm f/4G ED VR Wide Angle Zoom Lens. I have already Nikon 50mm 1.8G. Thanks for any advice.
Is your 50mm 1.8G extremely sharp? It's one of the sharper lenses out there. If there's still sharpness issues with that lens, then your D7000 likely has some focusing issues.
Your 18-105mm should be nearly as sharp as your 50mm 1.8G at the same apertures (the 50mm 1.8G will win out of course). Are you certain you're shooting with a fast enough shutter speed? Again, this could be a problem which relates to a frontfocus or backfocus issue. Take a look at the comparison between the two lenses:
Nikon 18-105mm f/3.5-5.6G AF-S ED VR DX Nikkor Lens Image Quality
The 18-105mm should be really sharp, so I recommend you find a shop or someone who can take a look at your D7000 and 18-105mm and give you an explanation after letting them analyse the situation. You should post up a full photo with a 100% crop example for us to take a look at possibly to get an idea of the sharpest 18mm shot you can get.
If you're enjoying wide shots and you want to go wider, and you don't like your camera, then just sell it. Sell the D7000, sell the 18-105mm. Possibly get warranty servicing first if that's applicable and makes sense. It sounds like you've got the money, so if you get a new camera, a D610 alongside some nice glass will show the difference (assuming you're not making any major mistakes currently that are contributing to the softness you see in your photos). Heck, you could spend more if you love landscape and you want to print big, and get a D800. I think that all depends on your budget and what makes sense to you though. Remember that something newer and greater comes out every year or two.
