Focusing Issue : lens issue ?

[Dolby]

This photo is a little difficult to see due to the size - but the stars are out of focus and the foreground is relatively sharp. I used a 28mm F2.8 and manually set to Infinity focus - but distant subjects aren't sharp.

Is it because the lens is a cheapy?
Surely infinity should make everything sharp in the distance?

EDIT : 30 second exposure ... but surely not enough for the stars to move?

 

[genetic]

You'd be surprised how much the stars can move in 30'

I'm sure that's the issue.

 

[nanonyous]

30" for 28mm shouldn't introduce much, if any, motion blur.
Op, keep in mind that most of Canon's SLR lenses can focus 'beyond' infinity. Assess what your hyperfocal distance is for the aperture you're using combined with your focal length, then focus just a smidge beyond that to make sure things should be in focus. Everything beyond the hyperfocal point ought to be in focus anyway - you'd primarily be losing foreground focus then as the focal point moves further away from you.

 

[BigAl-sa]

You'd be surprised how much the stars can move in 30'

I'm sure that's the issue.

Just a point 30' is 30 minutes. 30" is 30 seconds.

To the OP, you need a super steady tripod, with a cable release (and mirror lockup) on the camera to get a sharp pic, especially if there's any wind. The buildings in the foreground aren't that sharp, and anything that causes a lack of sharpness is exaggerated by distance.

 

[nanonyous]

Just a point 30' is 30 minutes. 30" is 30 seconds.

herp

 

[Dolby]

THanks guys!