The effect you are seeing is normal.
The camera is not jumping, and the cube is not in two places at once, it is just a trick of your eyes.
Movies run at 24fps. They look smooth, but they only look smooth because cameras have motion blur and computer graphics do not. Your computer screen updates at a minimum of 60fps. And even this appears to flicker to some people, like myself, so 85hz is becoming the norm.
Your eyes are sensitive to changes in brightness, and they have a long decay time so you see an image for a little while after the image has changed. With an image like this, the color goes instanty from white to black, and your eye takes a moment to adjust. Also your brain processes the information in funny ways. If a green pendulum swings back and forth and changes to red suddenly at the end of a swing, you will see the pendulum fade from green to red, over the course of the swing even though that is physically impossible because the pendulum didn't change color until the end of the swing.
This effect is caused either by your eyes or by your brain interpreting what your eyes see.
Either way, in order to get rid of this effect, you'd either have to have motion blur, which you can forget about if your game can't run at over 30fps to begine with, or you have to run at a higher framerate.
Graphics with lower contrast will reduce the effect. A white cube, or a textured cube, on a black background has high contrast so the effect is very obvious. In a game, things in the environment are roughtly the same color as other stuff around them, so your eye doesn't see the double image. Also, if the player controls the game with the mouse so the rotation speed varies, that appears to help too.
In short, you aren't doing anything wrong. Your eyes are. :-)
The camera is not jumping, and the cube is not in two places at once, it is just a trick of your eyes.
Movies run at 24fps. They look smooth, but they only look smooth because cameras have motion blur and computer graphics do not. Your computer screen updates at a minimum of 60fps. And even this appears to flicker to some people, like myself, so 85hz is becoming the norm.
Your eyes are sensitive to changes in brightness, and they have a long decay time so you see an image for a little while after the image has changed. With an image like this, the color goes instanty from white to black, and your eye takes a moment to adjust. Also your brain processes the information in funny ways. If a green pendulum swings back and forth and changes to red suddenly at the end of a swing, you will see the pendulum fade from green to red, over the course of the swing even though that is physically impossible because the pendulum didn't change color until the end of the swing.
This effect is caused either by your eyes or by your brain interpreting what your eyes see.
Either way, in order to get rid of this effect, you'd either have to have motion blur, which you can forget about if your game can't run at over 30fps to begine with, or you have to run at a higher framerate.
Graphics with lower contrast will reduce the effect. A white cube, or a textured cube, on a black background has high contrast so the effect is very obvious. In a game, things in the environment are roughtly the same color as other stuff around them, so your eye doesn't see the double image. Also, if the player controls the game with the mouse so the rotation speed varies, that appears to help too.
In short, you aren't doing anything wrong. Your eyes are. :-)