Hello, sadly PhotoStage does not offer the option to control the speed while applying other effects like zoom, nor you can select to apply different speeds on the different image. That type of editing is offered on Video editors like Videopad where you can split the video and apply different speeds to each piece of the video. Back to PhotoStage, the zoom effect only has one speed which will depend on the length of the image, for example, if the image last 3 seconds then the zoom will be done within that time, while if the image last 10 seconds then you will see that the zoom is done more smoother as it has more time to run.