If this photo is representative of this lens then the lens in not very sharp. The woman is in focus and the man is not.They appear to be the same distance from the lens so it isnot a dof problem.
I live in the high desert area of Oregon and it is very dry here. My 7D is 3 years old and so far no dust on sensor or shutter (knock on wood) and I check it regularly. I'm sure there is dust in there but it isn't a problem yet.
I have used teleconverters but I won't again. They cause too many problems and they are too much of an unsatisfactory compromise. I am going to unload mine and never look back. They don't work on all lenses and the picture quality isn't as good as I want. I am really against them as they just don't work well in my experience.
It will probably be cheaper to replace the camera than repair it. Camera goes for 100-150 now. I know you can find one that will replace yours for less than repairing yours, or you may want to get a good used upgrade.
Nikonian72 is in Long Beach CA so it isn't surprising he doesn't understand the question. I have a pair of shooting gloves with the finger slots only 1/2 there. Work pretty well.
I've never "bought" into that line. Of course you get what you pay for. You walk around the store, pick up what you want, and take it to the register. Then you pay for it and take it home. A no-brainer. It's nonsense to think that something is better just because it costs more.
If I want a lens or a camera or a car, I read all the reviews and articles that I can. Then I buy the one that seems best, provided I can afford it. There are many reasons why one lens costs more than another. As far as I'm concerned, reviews are king The Tamron is faster than the Nikon ($$), and it is twice the focal length. And Amazon has it for over a little over $600. http://www.amazon.com/Tamron-AFF004C700-90MM-2-8-MACRO/dp/B00A35WYJC
I've never "bought" into that line. Of ... (show quote)
If you search you can get some good deals on 7D's. I bought a used one a couple of months back for less than $500.00 and it has less than 10000. actuations. You have to search but it is getting a bit long in the tooth but it is still a wonderful camera. I now own 2 of them and there is nothing out there right now that I would trade them for. Good luck.