Thanks to everyone for their responses! Got very busy in my life after posting this querry, and just now trying to get up to speed on the answers.
Btw, I do want for all the photos I use to always zoom very slowly from the center. That is a constant throughout the video.
Using the method I posted that I have tried, I feel like I'm almost there. I must simply be overlooking a step. Here's a recap:
1) I select "fx" aka "Effects Room" on lefthand column menu.
2) Click and drag "Zoom in" onto the photo in the timeline (which I guess is basically a video clip since it runs for a duration of time in the video).
3) Click the "Effect" button on the menu row in the lower middle of the user interface.
4) There appears two sliders, one for "height" and one for "width." I want for the dimensions of the picture to remain constant, so I select the same value for both height and width. As mentioned, the pictures I'm inserting into the timeline are essentially videos, I guess, in the sense that they run as part of the movie for however many seconds I select for each within the timeline.
In any event, whatever value I enter for the height and width zoom, I don't actually see any zoom taking place when I select "play" to see how the effect looks for the duration of time that the photo (i.e., video clip of the photo) is displayed in the timeline.
I must be overlooking a step. What further do I need to do?
Edit: Okay, I think I've got it now. I had to open "keyframe." Then I set the sliders at zero for the start and entered a value of 4 or 5 at the end for a duration of around 10 seconds. That results in the very slow and slight zoom that I'm looking for.
This message was edited 8 times. Last update was at Jul 29. 2018 12:16