dcsmith40D wrote in post #7181009
When you wrote rotated 180 degrees, I wonder with respect to what was in rotated?
With respect to the bright parts that produced the ghosts. If you look at the second picture (single firefighter on ladder) the ghosts of the lower leg tape is above his head, while the ghosts of his jacket tape is below his belt line. Also, the ghosts are flipped both top-to-bottom and left-to right (look at the angles involved), which is equivalent to a 180° rotation.
Since most ghosts are not flipped at all, I just find this double flip an interesting effect. It has to be a property of the 70-200 2.8 IS used.
And to the OP: yes, you should definitely remove UV filters at night. Doing so may solve your ghost problem completely.
Like you, I was of the "filters for protection" mindset. However, experience has taught me that a good lens hood offers much more protection than a filter ever would, without introducing any optical problems.
EXCEPTION! Always use a filter when shooting in very windy conditions, as blowing grit or ice can and will scratch the coatings on the front lens element. But that's in very windy conditions, a breeze causes no problems.
Naturally, you should always blow off the surface of the lens before using either a brush or cloth to clean it. And use a Rocket blower or equivalent, never your mouth! The moisture in your breath can make grit adhere to the surface of the lens.
