I just got myself a Nikon D90 yesterday, and I've spent the past day reading and trying to figure it out. I'm not totally new to this, but definitely still a beginner. I took this photo of my dog today, and I'm curious as to why the background seems pretty pixeled. I DO NOT use anything auto because I want to force myself to figure everything out, but I'm not quite sure what to do for this one. I'm trying to get my pictures clean, sharp and vibrant.
All lenses have Depth of Field, DOF, or an area over which objects have an acceptable focus. If you want more, then you need to use a higher f-stop but you can not exceed f/11 or diffraction will occurs and you image will not be sharp.
Hi, again, Hillary, I think the background you are seeing is from the high ISO selected from this shot.
There are programs that you can use in post processing like Noise Ninja or Neat Image to clean up the noise (pixelization) in the background, however shooting at the base ISO (I believe it is ISO 200 in the D90) will keep noise from entering into the image. Thom Hogan says that you can get very usable images to ISO 800 and your image at ISO 1600 doesn't look bad (to my eye).
I'm sure you'll get other response from more experienced members.