This problem usually occurs after viewing a video and  before running Poser.

When it occurs, use the "Undo" function (if available) and then ...

Press the "space bar" ...
... this appears to clear the problem and then cameras work normally.

cheers,
dr geep
;=]

P.S. If "Undo" is not available ...
You can use the small arrowhead to the right of a parameter dial to "Reset" the parameter.
Do this for all of the camera's parameters that have abnormal or out of range values.

Remember ... "With Poser, all things are possible, and poseable!"

cheers,

dr geep ... :o]

edited 10/5/2019