END OF AN ERA, FRACTALFORUMS.COM IS CONTINUED ON FRACTALFORUMS.ORG

What program do you mean?  There is no program called Mandelbulb - most people mean either Mandelbulber or Mandelbulb3D when they say that.

Are you referring to an image sequence?

If so, they assume no frame rate and it's all up to you to set that in your video editor.  Perhaps it's a preference setting in your editor?

By definition an image sequence has no reference to frame rates at all - it's just a series of images which you can render at any frame rate you like.

Hope that helps   

sock is right, image sequences just have no time information, this is something you need to handle by enough frames between keyframes,
a test rendering in the preview window can be very helpful, it is in the animation window, you have to decide how many frames you want to
render, generally speaking, the more frames, the more smooth.