making a movie with PNG images

Not really. iMovie is a DV editor.

Try QuickTime Pro instead.

Hi

As Lennart writes. But I would try to.
Put my .png in a folder.
Get GraphicConverter ($30 I guess) and convert this folder to .jpg (I think should work OK)
Import them into iMovie
Change each photo duration - tedious
Test and see if it works.

Yours Bengt W

iMovie is a DV editor so your image files would need to be converted at import and you would lose the alpha channel (if used) found in your .png files.
QuickTime Pro can import images as a "sequence" and you can control the frame rate at creation to make a "moving image" file. It can also take advantage of an alpha channel found in some .png files.
It can import thousands of files and you can set the frame rate up to 60 fps down to 10 seconds per frame.