one thing you can do is buy a level for your camera.
something like this:
http://www.amazon.com/Triple-Bubble-Level-Spirit-Mount/dp/B0036WFND8
alternatively you can try to look at your horizons more when shooting to ensure they are level
one thing you can do is buy a level for your camera.
something like this:
http://www.amazon.com/Triple-Bubble-Level-Spirit-Mount/dp/B0036WFND8
alternatively you can try to look at your horizons more when shooting to ensure they are level