I got a dark spot!
 

This is a bit off subject but close enough for me:
I have a spot on my Nikon D3100, it is not the lens.
I went into the menu and did the "clean the sensor" option, but it did not help.
It is near the top about 1/3 of the way in from the left, can't miss it on a sky shot like this.

Any ideas?

Some additional information
 

It seems to be visible in shots that are sky blue. I have shot I did of objects on a withe background and there is no visible blemish. I can't seem to see it any other time.

(I currently doing a bunch of sky/cloud photos, guess that's why I have noticed it now.)

Re: I got a dark spot!
 

You need to pick up a sensor cleaning swab at a photography store. I've had this on my D600.

Re: I got a dark spot!
 

That's clearly a dust spot on your sensor, happens a lot to me, especially on my nex-ea50, I always use my arctic butterfly before every shoot to clean the sensor, works very well.

Re: I got a dark spot!
 

My d800 had numerous spots that appeared after several time lapse sessions. Some Nikons have an issue with oil getting on the sensor and I wasn't able to clean mine with a cleaning kit in fact that made the spots worse. Nikon fixed it at no charge.

Re: I got a dark spot!
 

Thanks a lot guys, glad it is just dirt. I did some googling on sensor cleaning and I think I'm going to get someone who knows what they're doing to clean it for me. I didn't pay a lot for this camera but I'm not 100% sure of the process - it seems it is possible to screw things up.

Thanks again!