Setting time limits before... or after keyframing? And how do I set them?

Question

Ok, I'm nearly 60 years old so I guess my learning abilities are decreasing. I'm trying to learn both FinalCut and Motion and am in my first project for a client. Part of it involves moving four images across the screen (school report cards) at different times gradually changing opacity in the process as each one goes out of view. I'm needing to have each one be in and almost out of the screen at 4.5 seconds. While one is leaving another is already entering at it's 4.5 second allotment. This is because of a music track that requires that time limit.
Aside from that fact that I'm trying to learn keyframing to do this I need some advice. It's a dual question:
1. Should I first set some kind of beginning and ending time frame for the whole thing, i.e. 18seconds, or should I create four different 4.5 second intervals somehow? I'm kinda stumped on that but think the timing must be set before I try and keyframe the images through. Hope that makes sense.
2. I'm trying the Lynda.Com tutorials on Motion but just still not getting enough specific help. Any tutorial suggestions?
Thank you very much.

Answer 1

hi
if you scroll along the timeline you can see the current position of the playhead in the little rounded box with a clock next to it, on the left hand side of the canvas. So its a case of doing a little maths, if your image comes in a 1.5 seconds then you need drag the playhead along until the counter reads 6 seconds.
OR you could press "+415" then hit return and the playheads will jump 4 seconds and 15 frames ahead. and you can move forward or backwards by a frame by pressing the left and right arrow keys.
So now you can set the length of the object to this duration by hovering the mouse right on the end of the object in the timeline and dragging. The cursor should change from an arrow to a left or right square bracket, depending on which end of the object you are at.
OR you can park the playhead at the point you want it to end as we discussed above, and select the object you want to change and the press " o" or the mark out button. The object will now be 4.5 seconds long.
I'm not sure what you mean when you say set a timing of the full 18 seconds. The timing of what? The project, the object?
hth, ask more questions if not. I suspect I'm not understanding the question fully which is why i cant answer it.
adam